diff --git a/src/Makefile.am b/src/Makefile.am
new file mode 100644
index 0000000..6876f68
--- /dev/null
+++ b/src/Makefile.am
@@ -0,0 +1,46 @@
+AM_CPPFLAGS = \
+	$(all_includes) \
+	-I$(top_srcdir)/include \
+	-I$(top_builddir) \
+	$(NULL)
+
+AM_CFLAGS = \
+	-Wall \
+	-fno-strict-aliasing \
+	$(LIBOSMOCORE_CFLAGS) \
+	$(LIBOSMOGSM_CFLAGS) \
+	$(LIBOSMOVTY_CFLAGS) \
+	$(LIBOSMOCTRL_CFLAGS) \
+	$(LIBOSMOABIS_CFLAGS) \
+	$(LIBOSMOGB_CFLAGS) \
+	$(LIBOSMOGSUPCLIENT_CFLAGS) \
+	$(COVERAGE_CFLAGS) \
+	$(LIBGTP_CFLAGS) \
+	$(NULL)
+
+bin_PROGRAMS = \
+	osmo-gbproxy \
+	$(NULL)
+
+osmo_gbproxy_SOURCES = \
+	gb_proxy.c \
+	gb_proxy_main.c \
+	gb_proxy_vty.c \
+	gb_proxy_ctrl.c \
+	gb_proxy_patch.c \
+	gb_proxy_tlli.c \
+	gb_proxy_peer.c \
+	$(NULL)
+osmo_gbproxy_LDADD = \
+	$(top_builddir)/src/gprs/gprs_gb_parse.o \
+	$(top_builddir)/src/gprs/gprs_llc_parse.o \
+	$(top_builddir)/src/gprs/crc24.o \
+	$(top_builddir)/src/gprs/gprs_utils.o \
+	$(LIBOSMOCORE_LIBS) \
+	$(LIBOSMOGSM_LIBS) \
+	$(LIBOSMOVTY_LIBS) \
+	$(LIBOSMOCTRL_LIBS) \
+	$(LIBOSMOGB_LIBS) \
+	$(LIBGTP_LIBS) \
+	-lrt \
+	$(NULL)
diff --git a/src/gb_proxy.c b/src/gb_proxy.c
new file mode 100644
index 0000000..3f471ff
--- /dev/null
+++ b/src/gb_proxy.c
@@ -0,0 +1,1454 @@
+/* NS-over-IP proxy */
+
+/* (C) 2010 by Harald Welte <laforge@gnumonks.org>
+ * (C) 2010-2013 by On-Waves
+ * (C) 2013 by Holger Hans Peter Freyther
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <getopt.h>
+#include <errno.h>
+#include <sys/fcntl.h>
+#include <sys/stat.h>
+#include <arpa/inet.h>
+#include <time.h>
+
+#include <osmocom/core/talloc.h>
+#include <osmocom/core/select.h>
+#include <osmocom/core/rate_ctr.h>
+#include <osmocom/core/stats.h>
+
+#include <osmocom/gprs/gprs_ns.h>
+#include <osmocom/gprs/gprs_bssgp.h>
+
+#include <osmocom/gsm/gsm_utils.h>
+
+#include <osmocom/sgsn/signal.h>
+#include <osmocom/sgsn/debug.h>
+#include <osmocom/sgsn/gprs_gb_parse.h>
+#include <osmocom/sgsn/gb_proxy.h>
+
+#include <osmocom/sgsn/gprs_llc.h>
+#include <osmocom/gsm/protocol/gsm_04_08_gprs.h>
+#include <osmocom/sgsn/gprs_utils.h>
+
+extern void *tall_sgsn_ctx;
+
+static const struct rate_ctr_desc global_ctr_description[] = {
+	{ "inv-bvci",	    "Invalid BVC Identifier          " },
+	{ "inv-lai",	    "Invalid Location Area Identifier" },
+	{ "inv-rai",	    "Invalid Routing Area Identifier " },
+	{ "inv-nsei",	    "No BVC established for NSEI     " },
+	{ "proto-err:bss",  "BSSGP protocol error      (BSS )" },
+	{ "proto-err:sgsn", "BSSGP protocol error      (SGSN)" },
+	{ "not-supp:bss",   "Feature not supported     (BSS )" },
+	{ "not-supp:sgsn",  "Feature not supported     (SGSN)" },
+	{ "restart:sgsn",   "Restarted RESET procedure (SGSN)" },
+	{ "tx-err:sgsn",    "NS Transmission error     (SGSN)" },
+	{ "error",          "Other error                     " },
+	{ "mod-peer-err",   "Patch error: no peer            " },
+};
+
+static const struct rate_ctr_group_desc global_ctrg_desc = {
+	.group_name_prefix = "gbproxy:global",
+	.group_description = "GBProxy Global Statistics",
+	.num_ctr = ARRAY_SIZE(global_ctr_description),
+	.ctr_desc = global_ctr_description,
+	.class_id = OSMO_STATS_CLASS_GLOBAL,
+};
+
+static int gbprox_relay2peer(struct msgb *old_msg, struct gbproxy_peer *peer,
+			  uint16_t ns_bvci);
+static int gbprox_relay2sgsn(struct gbproxy_config *cfg, struct msgb *old_msg,
+			     uint16_t ns_bvci, uint16_t sgsn_nsei);
+static void gbproxy_reset_imsi_acquisition(struct gbproxy_link_info* link_info);
+
+static int check_peer_nsei(struct gbproxy_peer *peer, uint16_t nsei)
+{
+	if (peer->nsei != nsei) {
+		LOGP(DGPRS, LOGL_NOTICE, "Peer entry doesn't match current NSEI "
+		     "BVCI=%u via NSEI=%u (expected NSEI=%u)\n",
+		     peer->bvci, nsei, peer->nsei);
+		rate_ctr_inc(&peer->ctrg->ctr[GBPROX_PEER_CTR_INV_NSEI]);
+		return 0;
+	}
+
+	return 1;
+}
+
+/* strip off the NS header */
+static void strip_ns_hdr(struct msgb *msg)
+{
+	int strip_len = msgb_bssgph(msg) - msg->data;
+	msgb_pull(msg, strip_len);
+}
+
+/* Transmit Chapter 9.2.10 Identity Request */
+static void gprs_put_identity_req(struct msgb *msg, uint8_t id_type)
+{
+	struct gsm48_hdr *gh;
+
+	id_type &= GSM_MI_TYPE_MASK;
+
+	gh = (struct gsm48_hdr *) msgb_put(msg, sizeof(*gh) + 1);
+	gh->proto_discr = GSM48_PDISC_MM_GPRS;
+	gh->msg_type = GSM48_MT_GMM_ID_REQ;
+	gh->data[0] = id_type;
+}
+
+/* Transmit Chapter 9.4.6.2 Detach Accept (mobile originated detach) */
+static void gprs_put_mo_detach_acc(struct msgb *msg)
+{
+	struct gsm48_hdr *gh;
+
+	gh = (struct gsm48_hdr *) msgb_put(msg, sizeof(*gh) + 1);
+	gh->proto_discr = GSM48_PDISC_MM_GPRS;
+	gh->msg_type = GSM48_MT_GMM_DETACH_ACK;
+	gh->data[0] = 0; /* no force to standby */
+}
+
+static void gprs_push_llc_ui(struct msgb *msg,
+			     int is_uplink, unsigned sapi, unsigned nu)
+{
+	const uint8_t e_bit = 0;
+	const uint8_t pm_bit = 1;
+	const uint8_t cr_bit = is_uplink ? 0 : 1;
+	uint8_t *llc;
+	uint8_t *fcs_field;
+	uint32_t fcs;
+
+	nu &= 0x01ff; /* 9 Bit */
+
+	llc = msgb_push(msg, 3);
+	llc[0] = (cr_bit << 6) | (sapi & 0x0f);
+	llc[1] = 0xc0 | (nu >> 6); /* UI frame */
+	llc[2] = (nu << 2) | ((e_bit & 1) << 1) | (pm_bit & 1);
+
+	fcs = gprs_llc_fcs(llc, msgb_length(msg));
+	fcs_field = msgb_put(msg, 3);
+	fcs_field[0] = (uint8_t)(fcs >> 0);
+	fcs_field[1] = (uint8_t)(fcs >> 8);
+	fcs_field[2] = (uint8_t)(fcs >> 16);
+}
+
+static void gprs_push_bssgp_dl_unitdata(struct msgb *msg,
+					uint32_t tlli)
+{
+	struct bssgp_ud_hdr *budh;
+	uint8_t *llc = msgb_data(msg);
+	size_t llc_size = msgb_length(msg);
+	const size_t llc_ie_hdr_size = 3;
+	const uint8_t qos_profile[] = {0x00, 0x50, 0x20}; /* hard-coded */
+	const uint8_t lifetime[] = {0x02, 0x58}; /* 6s hard-coded */
+
+	const size_t bssgp_overhead = sizeof(*budh) +
+		TVLV_GROSS_LEN(sizeof(lifetime)) + llc_ie_hdr_size;
+	uint8_t *ie;
+	uint32_t tlli_be = htonl(tlli);
+
+	budh = (struct bssgp_ud_hdr *)msgb_push(msg, bssgp_overhead);
+
+	budh->pdu_type = BSSGP_PDUT_DL_UNITDATA;
+	memcpy(&budh->tlli, &tlli_be, sizeof(budh->tlli));
+	memcpy(&budh->qos_profile, qos_profile, sizeof(budh->qos_profile));
+
+	ie = budh->data;
+	tvlv_put(ie, BSSGP_IE_PDU_LIFETIME, sizeof(lifetime), lifetime);
+	ie += TVLV_GROSS_LEN(sizeof(lifetime));
+
+	/* Note: Add alignment before the LLC IE if inserting other IE */
+
+	*(ie++) = BSSGP_IE_LLC_PDU;
+	*(ie++) = llc_size / 256;
+	*(ie++) = llc_size % 256;
+
+	OSMO_ASSERT(ie == llc);
+
+	msgb_bssgph(msg) = (uint8_t *)budh;
+	msgb_tlli(msg) = tlli;
+}
+
+/* update peer according to the BSS message */
+static void gbprox_update_current_raid(uint8_t *raid_enc,
+				       struct gbproxy_peer *peer,
+				       const char *log_text)
+{
+	struct gbproxy_patch_state *state = &peer->patch_state;
+	const struct osmo_plmn_id old_plmn = state->local_plmn;
+	struct gprs_ra_id raid;
+
+	if (!raid_enc)
+		return;
+
+	gsm48_parse_ra(&raid, raid_enc);
+
+	/* save source side MCC/MNC */
+	if (!peer->cfg->core_plmn.mcc || raid.mcc == peer->cfg->core_plmn.mcc) {
+		state->local_plmn.mcc = 0;
+	} else {
+		state->local_plmn.mcc = raid.mcc;
+	}
+
+	if (!peer->cfg->core_plmn.mnc
+	    || !osmo_mnc_cmp(raid.mnc, raid.mnc_3_digits,
+			     peer->cfg->core_plmn.mnc, peer->cfg->core_plmn.mnc_3_digits)) {
+		state->local_plmn.mnc = 0;
+		state->local_plmn.mnc_3_digits = false;
+	} else {
+		state->local_plmn.mnc = raid.mnc;
+		state->local_plmn.mnc_3_digits = raid.mnc_3_digits;
+	}
+
+	if (osmo_plmn_cmp(&old_plmn, &state->local_plmn))
+		LOGP(DGPRS, LOGL_NOTICE,
+		     "Patching RAID %sactivated, msg: %s, "
+		     "local: %s, core: %s\n",
+		     state->local_plmn.mcc || state->local_plmn.mnc ?
+		     "" : "de",
+		     log_text,
+		     osmo_plmn_name(&state->local_plmn),
+		     osmo_plmn_name2(&peer->cfg->core_plmn));
+}
+
+uint32_t gbproxy_make_bss_ptmsi(struct gbproxy_peer *peer,
+				uint32_t sgsn_ptmsi)
+{
+	uint32_t bss_ptmsi;
+	int max_retries = 23, rc = 0;
+	if (!peer->cfg->patch_ptmsi) {
+		bss_ptmsi = sgsn_ptmsi;
+	} else {
+		do {
+			rc = osmo_get_rand_id((uint8_t *) &bss_ptmsi, sizeof(bss_ptmsi));
+			if (rc < 0) {
+				bss_ptmsi = GSM_RESERVED_TMSI;
+				break;
+			}
+
+			bss_ptmsi = bss_ptmsi | GSM23003_TMSI_SGSN_MASK;
+
+			if (gbproxy_link_info_by_ptmsi(peer, bss_ptmsi))
+				bss_ptmsi = GSM_RESERVED_TMSI;
+		} while (bss_ptmsi == GSM_RESERVED_TMSI && max_retries--);
+	}
+
+	if (bss_ptmsi == GSM_RESERVED_TMSI)
+		LOGP(DGPRS, LOGL_ERROR, "Failed to allocate a BSS P-TMSI: %d (%s)\n", rc, strerror(-rc));
+
+	return bss_ptmsi;
+}
+
+uint32_t gbproxy_make_sgsn_tlli(struct gbproxy_peer *peer,
+				struct gbproxy_link_info *link_info,
+				uint32_t bss_tlli)
+{
+	uint32_t sgsn_tlli;
+	int max_retries = 23, rc = 0;
+	if (!peer->cfg->patch_ptmsi) {
+		sgsn_tlli = bss_tlli;
+	} else if (link_info->sgsn_tlli.ptmsi != GSM_RESERVED_TMSI &&
+		   gprs_tlli_type(bss_tlli) == TLLI_FOREIGN) {
+		sgsn_tlli = gprs_tmsi2tlli(link_info->sgsn_tlli.ptmsi,
+					   TLLI_FOREIGN);
+	} else if (link_info->sgsn_tlli.ptmsi != GSM_RESERVED_TMSI &&
+		   gprs_tlli_type(bss_tlli) == TLLI_LOCAL) {
+		sgsn_tlli = gprs_tmsi2tlli(link_info->sgsn_tlli.ptmsi,
+					   TLLI_LOCAL);
+	} else {
+		do {
+			/* create random TLLI, 0b01111xxx... */
+			rc = osmo_get_rand_id((uint8_t *) &sgsn_tlli, sizeof(sgsn_tlli));
+			if (rc < 0) {
+				sgsn_tlli = 0;
+				break;
+			}
+
+			sgsn_tlli = (sgsn_tlli & 0x7fffffff) | 0x78000000;
+
+			if (gbproxy_link_info_by_any_sgsn_tlli(peer, sgsn_tlli))
+				sgsn_tlli = 0;
+		} while (!sgsn_tlli && max_retries--);
+	}
+
+	if (!sgsn_tlli)
+		LOGP(DGPRS, LOGL_ERROR, "Failed to allocate an SGSN TLLI: %d (%s)\n", rc, strerror(-rc));
+
+	return sgsn_tlli;
+}
+
+void gbproxy_reset_link(struct gbproxy_link_info *link_info)
+{
+	gbproxy_reset_imsi_acquisition(link_info);
+}
+
+/* Returns != 0 iff IMSI acquisition was in progress */
+static int gbproxy_restart_imsi_acquisition(struct gbproxy_link_info* link_info)
+{
+	int in_progress = 0;
+	if (!link_info)
+		return 0;
+
+	if (link_info->imsi_acq_pending)
+		in_progress = 1;
+
+	gbproxy_link_info_discard_messages(link_info);
+	link_info->imsi_acq_pending = false;
+
+	return in_progress;
+}
+
+static void gbproxy_reset_imsi_acquisition(struct gbproxy_link_info* link_info)
+{
+	gbproxy_restart_imsi_acquisition(link_info);
+	link_info->vu_gen_tx_bss = GBPROXY_INIT_VU_GEN_TX;
+}
+
+/* Got identity response with IMSI, assuming the request had
+ * been generated by the gbproxy */
+static int gbproxy_flush_stored_messages(struct gbproxy_peer *peer,
+					  time_t now,
+					  struct gbproxy_link_info* link_info)
+{
+	int rc;
+	struct msgb *stored_msg;
+
+	/* Patch and flush stored messages towards the SGSN */
+	while ((stored_msg = msgb_dequeue_count(&link_info->stored_msgs,
+						&link_info->stored_msgs_len))) {
+		struct gprs_gb_parse_context tmp_parse_ctx = {0};
+		tmp_parse_ctx.to_bss = 0;
+		tmp_parse_ctx.peer_nsei = msgb_nsei(stored_msg);
+		int len_change = 0;
+
+		gprs_gb_parse_bssgp(msgb_bssgph(stored_msg),
+				    msgb_bssgp_len(stored_msg),
+				    &tmp_parse_ctx);
+		gbproxy_patch_bssgp(stored_msg, msgb_bssgph(stored_msg),
+				    msgb_bssgp_len(stored_msg),
+				    peer, link_info, &len_change,
+				    &tmp_parse_ctx);
+
+		rc = gbproxy_update_link_state_after(peer, link_info, now,
+				&tmp_parse_ctx);
+		if (rc == 1) {
+			LOGP(DLLC, LOGL_NOTICE, "link_info deleted while flushing stored messages\n");
+			msgb_free(stored_msg);
+			return -1;
+		}
+
+		rc = gbprox_relay2sgsn(peer->cfg, stored_msg,
+				       msgb_bvci(stored_msg), link_info->sgsn_nsei);
+
+		if (rc < 0)
+			LOGP(DLLC, LOGL_ERROR,
+			     "NSEI=%d(BSS) failed to send stored message "
+			     "(%s)\n",
+			     tmp_parse_ctx.peer_nsei,
+			     tmp_parse_ctx.llc_msg_name ?
+			     tmp_parse_ctx.llc_msg_name : "BSSGP");
+		msgb_free(stored_msg);
+	}
+
+	return 0;
+}
+
+static int gbproxy_gsm48_to_peer(struct gbproxy_peer *peer,
+				 struct gbproxy_link_info* link_info,
+				 uint16_t bvci,
+				 struct msgb *msg /* Takes msg ownership */)
+{
+	int rc;
+
+	/* Workaround to avoid N(U) collisions and to enable a restart
+	 * of the IMSI acquisition procedure. This will work unless the
+	 * SGSN has an initial V(UT) within [256-32, 256+n_retries]
+	 * (see GSM 04.64, 8.4.2). */
+	gprs_push_llc_ui(msg, 0, GPRS_SAPI_GMM, link_info->vu_gen_tx_bss);
+	link_info->vu_gen_tx_bss = (link_info->vu_gen_tx_bss + 1) % 512;
+
+	gprs_push_bssgp_dl_unitdata(msg, link_info->tlli.current);
+	rc = gbprox_relay2peer(msg, peer, bvci);
+	msgb_free(msg);
+	return rc;
+}
+
+static void gbproxy_acquire_imsi(struct gbproxy_peer *peer,
+				 struct gbproxy_link_info* link_info,
+				 uint16_t bvci)
+{
+	struct msgb *idreq_msg;
+
+	/* Send IDENT REQ */
+	idreq_msg = gsm48_msgb_alloc_name("GSM 04.08 ACQ IMSI");
+	gprs_put_identity_req(idreq_msg, GSM_MI_TYPE_IMSI);
+	gbproxy_gsm48_to_peer(peer, link_info, bvci, idreq_msg);
+}
+
+static void gbproxy_tx_detach_acc(struct gbproxy_peer *peer,
+				  struct gbproxy_link_info* link_info,
+				  uint16_t bvci)
+{
+	struct msgb *detacc_msg;
+
+	/* Send DETACH ACC */
+	detacc_msg = gsm48_msgb_alloc_name("GSM 04.08 DET ACC");
+	gprs_put_mo_detach_acc(detacc_msg);
+	gbproxy_gsm48_to_peer(peer, link_info, bvci, detacc_msg);
+}
+
+/* Return != 0 iff msg still needs to be processed */
+static int gbproxy_imsi_acquisition(struct gbproxy_peer *peer,
+				    struct msgb *msg,
+				    time_t now,
+				    struct gbproxy_link_info* link_info,
+				    struct gprs_gb_parse_context *parse_ctx)
+{
+	struct msgb *stored_msg;
+
+	if (!link_info)
+		return 1;
+
+	if (!link_info->imsi_acq_pending && link_info->imsi_len > 0)
+		return 1;
+
+	if (parse_ctx->g48_hdr)
+		switch (parse_ctx->g48_hdr->msg_type)
+		{
+		case GSM48_MT_GMM_RA_UPD_REQ:
+		case GSM48_MT_GMM_ATTACH_REQ:
+			if (gbproxy_restart_imsi_acquisition(link_info)) {
+				LOGP(DLLC, LOGL_INFO,
+				     "NSEI=%d(BSS) IMSI acquisition was in progress "
+				     "when receiving an %s.\n",
+				     msgb_nsei(msg), parse_ctx->llc_msg_name);
+			}
+			break;
+		case GSM48_MT_GMM_DETACH_REQ:
+			/* Nothing has been sent to the SGSN yet */
+			if (link_info->imsi_acq_pending) {
+				LOGP(DLLC, LOGL_INFO,
+				     "NSEI=%d(BSS) IMSI acquisition was in progress "
+				     "when receiving a DETACH_REQ.\n",
+				     msgb_nsei(msg));
+			}
+			if (!parse_ctx->invalidate_tlli) {
+				LOGP(DLLC, LOGL_INFO,
+				     "NSEI=%d(BSS) IMSI not yet acquired, "
+				     "faking a DETACH_ACC.\n",
+				     msgb_nsei(msg));
+				gbproxy_tx_detach_acc(peer, link_info, msgb_bvci(msg));
+				parse_ctx->invalidate_tlli = 1;
+			}
+			gbproxy_reset_imsi_acquisition(link_info);
+			gbproxy_update_link_state_after(peer, link_info, now,
+							parse_ctx);
+			return 0;
+		}
+
+	if (link_info->imsi_acq_pending && link_info->imsi_len > 0) {
+		int is_ident_resp =
+			parse_ctx->g48_hdr &&
+			gsm48_hdr_pdisc(parse_ctx->g48_hdr) == GSM48_PDISC_MM_GPRS &&
+			gsm48_hdr_msg_type(parse_ctx->g48_hdr) == GSM48_MT_GMM_ID_RESP;
+
+		LOGP(DLLC, LOGL_DEBUG,
+		     "NSEI=%d(BSS) IMSI acquisition succeeded, "
+		     "flushing stored messages\n",
+		     msgb_nsei(msg));
+		/* The IMSI is now available. If flushing the messages fails,
+		 * then link_info has been deleted and we should return
+		 * immediately. */
+		if (gbproxy_flush_stored_messages(peer, now, link_info) < 0)
+			return 0;
+
+		gbproxy_reset_imsi_acquisition(link_info);
+
+		/* This message is most probably the response to the ident
+		 * request sent by gbproxy_acquire_imsi(). Don't forward it to
+		 * the SGSN. */
+		return !is_ident_resp;
+	}
+
+	/* The message cannot be processed since the IMSI is still missing */
+
+	/* If queue is getting too large, drop oldest msgb before adding new one */
+	if (peer->cfg->stored_msgs_max_len > 0) {
+		int exceeded_max_len = link_info->stored_msgs_len
+				   + 1 - peer->cfg->stored_msgs_max_len;
+
+		for (; exceeded_max_len > 0; exceeded_max_len--) {
+			struct msgb *msgb_drop;
+			msgb_drop = msgb_dequeue_count(&link_info->stored_msgs,
+						       &link_info->stored_msgs_len);
+			LOGP(DLLC, LOGL_INFO,
+			     "NSEI=%d(BSS) Dropping stored msgb from list "
+			     "(!acq imsi, length %d, max_len exceeded)\n",
+			     msgb_nsei(msgb_drop), link_info->stored_msgs_len);
+
+			msgb_free(msgb_drop);
+		}
+	}
+
+	/* Enqueue unpatched messages */
+	LOGP(DLLC, LOGL_INFO,
+	     "NSEI=%d(BSS) IMSI acquisition in progress, "
+	     "storing message (%s)\n",
+	     msgb_nsei(msg),
+	     parse_ctx->llc_msg_name ? parse_ctx->llc_msg_name : "BSSGP");
+
+	stored_msg = bssgp_msgb_copy(msg, "process_bssgp_ul");
+	msgb_enqueue_count(&link_info->stored_msgs, stored_msg,
+			   &link_info->stored_msgs_len);
+
+	if (!link_info->imsi_acq_pending) {
+		LOGP(DLLC, LOGL_INFO,
+		     "NSEI=%d(BSS) IMSI is required but not available, "
+		     "initiating identification procedure (%s)\n",
+		     msgb_nsei(msg),
+		     parse_ctx->llc_msg_name ? parse_ctx->llc_msg_name : "BSSGP");
+
+		gbproxy_acquire_imsi(peer, link_info, msgb_bvci(msg));
+
+		/* There is no explicit retransmission handling, the
+		 * implementation relies on the MS doing proper retransmissions
+		 * of the triggering message instead */
+
+		link_info->imsi_acq_pending = true;
+	}
+
+	return 0;
+}
+
+struct gbproxy_peer *gbproxy_find_peer(struct gbproxy_config *cfg,
+				       struct msgb *msg,
+				       struct gprs_gb_parse_context *parse_ctx)
+{
+	struct gbproxy_peer *peer = NULL;
+
+	if (msgb_bvci(msg) >= 2)
+		peer = gbproxy_peer_by_bvci(cfg, msgb_bvci(msg));
+
+	if (!peer && !parse_ctx->to_bss)
+		peer = gbproxy_peer_by_nsei(cfg, msgb_nsei(msg));
+
+	if (!peer)
+		peer = gbproxy_peer_by_bssgp_tlv(cfg, &parse_ctx->bssgp_tp);
+
+	if (!peer) {
+		LOGP(DLLC, LOGL_INFO,
+		     "NSEI=%d(%s) patching: didn't find peer for message, "
+		     "PDU %d\n",
+		     msgb_nsei(msg), parse_ctx->to_bss ? "BSS" : "SGSN",
+		     parse_ctx->pdu_type);
+		/* Increment counter */
+		rate_ctr_inc(&cfg->ctrg->ctr[GBPROX_GLOB_CTR_PATCH_PEER_ERR]);
+	}
+	return peer;
+}
+
+/* patch BSSGP message */
+static int gbprox_process_bssgp_ul(struct gbproxy_config *cfg,
+				   struct msgb *msg,
+				   struct gbproxy_peer *peer)
+{
+	struct gprs_gb_parse_context parse_ctx = {0};
+	int rc;
+	int len_change = 0;
+	time_t now;
+	struct timespec ts = {0,};
+	struct gbproxy_link_info *link_info = NULL;
+	uint32_t sgsn_nsei = cfg->nsip_sgsn_nsei;
+
+	if (!cfg->core_plmn.mcc && !cfg->core_plmn.mnc && !cfg->core_apn &&
+	    !cfg->acquire_imsi && !cfg->patch_ptmsi && !cfg->route_to_sgsn2)
+		return 1;
+
+	parse_ctx.to_bss = 0;
+	parse_ctx.peer_nsei = msgb_nsei(msg);
+
+	/* Parse BSSGP/LLC */
+	rc = gprs_gb_parse_bssgp(msgb_bssgph(msg), msgb_bssgp_len(msg),
+				 &parse_ctx);
+
+	if (!rc && !parse_ctx.need_decryption) {
+		LOGP(DGPRS, LOGL_ERROR,
+		     "NSEI=%u(BSS) patching: failed to parse invalid %s message\n",
+		     msgb_nsei(msg), gprs_gb_message_name(&parse_ctx, "NS_UNITDATA"));
+		gprs_gb_log_parse_context(LOGL_NOTICE, &parse_ctx, "NS_UNITDATA");
+		LOGP(DGPRS, LOGL_NOTICE,
+		     "NSEI=%u(BSS) invalid message was: %s\n",
+		     msgb_nsei(msg), msgb_hexdump(msg));
+		return 0;
+	}
+
+	/* Get peer */
+	if (!peer)
+		peer = gbproxy_find_peer(cfg, msg, &parse_ctx);
+
+	if (!peer)
+		return 0;
+
+
+	osmo_clock_gettime(CLOCK_MONOTONIC, &ts);
+	now = ts.tv_sec;
+
+	gbprox_update_current_raid(parse_ctx.bssgp_raid_enc, peer,
+				   parse_ctx.llc_msg_name);
+
+	gprs_gb_log_parse_context(LOGL_DEBUG, &parse_ctx, "NS_UNITDATA");
+
+	link_info = gbproxy_update_link_state_ul(peer, now, &parse_ctx);
+
+	if (parse_ctx.g48_hdr) {
+		switch (parse_ctx.g48_hdr->msg_type) {
+		case GSM48_MT_GMM_ATTACH_REQ:
+			rate_ctr_inc(&peer->ctrg->ctr[GBPROX_PEER_CTR_ATTACH_REQS]);
+			break;
+		case GSM48_MT_GMM_DETACH_REQ:
+			rate_ctr_inc(&peer->ctrg->ctr[GBPROX_PEER_CTR_DETACH_REQS]);
+			break;
+		case GSM48_MT_GMM_ATTACH_COMPL:
+			rate_ctr_inc(&peer->ctrg->ctr[GBPROX_PEER_CTR_ATTACH_COMPLS]);
+			break;
+		case GSM48_MT_GMM_RA_UPD_REQ:
+			rate_ctr_inc(&peer->ctrg->ctr[GBPROX_PEER_CTR_RA_UPD_REQS]);
+			break;
+		case GSM48_MT_GMM_RA_UPD_COMPL:
+			rate_ctr_inc(&peer->ctrg->ctr[GBPROX_PEER_CTR_RA_UPD_COMPLS]);
+			break;
+		case GSM48_MT_GMM_STATUS:
+			rate_ctr_inc(&peer->ctrg->ctr[GBPROX_PEER_CTR_GMM_STATUS_BSS]);
+			break;
+		case GSM48_MT_GSM_ACT_PDP_REQ:
+			rate_ctr_inc(&peer->ctrg->ctr[GBPROX_PEER_CTR_PDP_ACT_REQS]);
+			break;
+		case GSM48_MT_GSM_DEACT_PDP_REQ:
+			rate_ctr_inc(&peer->ctrg->ctr[GBPROX_PEER_CTR_PDP_DEACT_REQS]);
+			break;
+
+		default:
+			break;
+		}
+	}
+
+	if (link_info && cfg->route_to_sgsn2) {
+		if (cfg->acquire_imsi && link_info->imsi_len == 0)
+			sgsn_nsei = 0xffff;
+		else if (gbproxy_imsi_matches(cfg, GBPROX_MATCH_ROUTING,
+					      link_info))
+			sgsn_nsei = cfg->nsip_sgsn2_nsei;
+	}
+
+	if (link_info)
+		link_info->sgsn_nsei = sgsn_nsei;
+
+	/* Handle IMSI acquisition */
+	if (cfg->acquire_imsi) {
+		rc = gbproxy_imsi_acquisition(peer, msg, now, link_info,
+					      &parse_ctx);
+		if (rc <= 0)
+			return rc;
+	}
+
+	gbproxy_patch_bssgp(msg, msgb_bssgph(msg), msgb_bssgp_len(msg),
+			    peer, link_info, &len_change, &parse_ctx);
+
+	gbproxy_update_link_state_after(peer, link_info, now, &parse_ctx);
+
+	if (sgsn_nsei != cfg->nsip_sgsn_nsei) {
+		/* Send message directly to the selected SGSN */
+		rc = gbprox_relay2sgsn(cfg, msg, msgb_bvci(msg), sgsn_nsei);
+		/* Don't let the calling code handle the transmission */
+		return 0;
+	}
+
+	return 1;
+}
+
+/* patch BSSGP message to use core_plmn.mcc/mnc on the SGSN side */
+static void gbprox_process_bssgp_dl(struct gbproxy_config *cfg,
+				    struct msgb *msg,
+				    struct gbproxy_peer *peer)
+{
+	struct gprs_gb_parse_context parse_ctx = {0};
+	int rc;
+	int len_change = 0;
+	time_t now;
+	struct timespec ts = {0,};
+	struct gbproxy_link_info *link_info = NULL;
+
+	if (!cfg->core_plmn.mcc && !cfg->core_plmn.mnc && !cfg->core_apn &&
+	    !cfg->acquire_imsi && !cfg->patch_ptmsi && !cfg->route_to_sgsn2)
+		return;
+
+	parse_ctx.to_bss = 1;
+	parse_ctx.peer_nsei = msgb_nsei(msg);
+
+	rc = gprs_gb_parse_bssgp(msgb_bssgph(msg), msgb_bssgp_len(msg),
+				 &parse_ctx);
+
+	if (!rc && !parse_ctx.need_decryption) {
+		LOGP(DGPRS, LOGL_ERROR,
+		     "NSEI=%u(SGSN) patching: failed to parse invalid %s message\n",
+		     msgb_nsei(msg), gprs_gb_message_name(&parse_ctx, "NS_UNITDATA"));
+		gprs_gb_log_parse_context(LOGL_NOTICE, &parse_ctx, "NS_UNITDATA");
+		LOGP(DGPRS, LOGL_NOTICE,
+		     "NSEI=%u(SGSN) invalid message was: %s\n",
+		     msgb_nsei(msg), msgb_hexdump(msg));
+		return;
+	}
+
+	/* Get peer */
+	if (!peer)
+		peer = gbproxy_find_peer(cfg, msg, &parse_ctx);
+
+	if (!peer)
+		return;
+
+	osmo_clock_gettime(CLOCK_MONOTONIC, &ts);
+	now = ts.tv_sec;
+
+	if (parse_ctx.g48_hdr) {
+		switch (parse_ctx.g48_hdr->msg_type) {
+		case GSM48_MT_GMM_ATTACH_ACK:
+			rate_ctr_inc(&peer->ctrg->ctr[GBPROX_PEER_CTR_ATTACH_ACKS]);
+			break;
+		case GSM48_MT_GMM_ATTACH_REJ:
+			rate_ctr_inc(&peer->ctrg->ctr[GBPROX_PEER_CTR_ATTACH_REJS]);
+			break;
+		case GSM48_MT_GMM_DETACH_ACK:
+			rate_ctr_inc(&peer->ctrg->ctr[GBPROX_PEER_CTR_DETACH_ACKS]);
+			break;
+		case GSM48_MT_GMM_RA_UPD_ACK:
+			rate_ctr_inc(&peer->ctrg->ctr[GBPROX_PEER_CTR_RA_UPD_ACKS]);
+			break;
+		case GSM48_MT_GMM_RA_UPD_REJ:
+			rate_ctr_inc(&peer->ctrg->ctr[GBPROX_PEER_CTR_RA_UPD_REJS]);
+			break;
+		case GSM48_MT_GMM_STATUS:
+			rate_ctr_inc(&peer->ctrg->ctr[GBPROX_PEER_CTR_GMM_STATUS_SGSN]);
+			break;
+		case GSM48_MT_GSM_ACT_PDP_ACK:
+			rate_ctr_inc(&peer->ctrg->ctr[GBPROX_PEER_CTR_PDP_ACT_ACKS]);
+			break;
+		case GSM48_MT_GSM_ACT_PDP_REJ:
+			rate_ctr_inc(&peer->ctrg->ctr[GBPROX_PEER_CTR_PDP_ACT_REJS]);
+			break;
+		case GSM48_MT_GSM_DEACT_PDP_ACK:
+			rate_ctr_inc(&peer->ctrg->ctr[GBPROX_PEER_CTR_PDP_DEACT_ACKS]);
+			break;
+
+		default:
+			break;
+		}
+	}
+
+	gprs_gb_log_parse_context(LOGL_DEBUG, &parse_ctx, "NS_UNITDATA");
+
+	link_info = gbproxy_update_link_state_dl(peer, now, &parse_ctx);
+
+	gbproxy_patch_bssgp(msg, msgb_bssgph(msg), msgb_bssgp_len(msg),
+			    peer, link_info, &len_change, &parse_ctx);
+
+	gbproxy_update_link_state_after(peer, link_info, now, &parse_ctx);
+
+	return;
+}
+
+/* feed a message down the NS-VC associated with the specified peer */
+static int gbprox_relay2sgsn(struct gbproxy_config *cfg, struct msgb *old_msg,
+			     uint16_t ns_bvci, uint16_t sgsn_nsei)
+{
+	/* create a copy of the message so the old one can
+	 * be free()d safely when we return from gbprox_rcvmsg() */
+	struct msgb *msg = bssgp_msgb_copy(old_msg, "msgb_relay2sgsn");
+	int rc;
+
+	DEBUGP(DGPRS, "NSEI=%u proxying BTS->SGSN (NS_BVCI=%u, NSEI=%u)\n",
+		msgb_nsei(msg), ns_bvci, sgsn_nsei);
+
+	msgb_bvci(msg) = ns_bvci;
+	msgb_nsei(msg) = sgsn_nsei;
+
+	strip_ns_hdr(msg);
+
+	rc = gprs_ns_sendmsg(bssgp_nsi, msg);
+	if (rc < 0)
+		rate_ctr_inc(&cfg->ctrg->ctr[GBPROX_GLOB_CTR_TX_ERR_SGSN]);
+
+	return rc;
+}
+
+/* feed a message down the NS-VC associated with the specified peer */
+static int gbprox_relay2peer(struct msgb *old_msg, struct gbproxy_peer *peer,
+			  uint16_t ns_bvci)
+{
+	/* create a copy of the message so the old one can
+	 * be free()d safely when we return from gbprox_rcvmsg() */
+	struct msgb *msg = bssgp_msgb_copy(old_msg, "msgb_relay2peer");
+	int rc;
+
+	DEBUGP(DGPRS, "NSEI=%u proxying SGSN->BSS (NS_BVCI=%u, NSEI=%u)\n",
+		msgb_nsei(msg), ns_bvci, peer->nsei);
+
+	msgb_bvci(msg) = ns_bvci;
+	msgb_nsei(msg) = peer->nsei;
+
+	/* Strip the old NS header, it will be replaced with a new one */
+	strip_ns_hdr(msg);
+
+	rc = gprs_ns_sendmsg(bssgp_nsi, msg);
+	if (rc < 0)
+		rate_ctr_inc(&peer->ctrg->ctr[GBPROX_PEER_CTR_TX_ERR]);
+
+	return rc;
+}
+
+static int block_unblock_peer(struct gbproxy_config *cfg, uint16_t ptp_bvci, uint8_t pdu_type)
+{
+	struct gbproxy_peer *peer;
+
+	peer = gbproxy_peer_by_bvci(cfg, ptp_bvci);
+	if (!peer) {
+		LOGP(DGPRS, LOGL_ERROR, "BVCI=%u: Cannot find BSS\n",
+			ptp_bvci);
+		rate_ctr_inc(&cfg->ctrg->ctr[GBPROX_GLOB_CTR_INV_BVCI]);
+		return -ENOENT;
+	}
+
+	switch (pdu_type) {
+	case BSSGP_PDUT_BVC_BLOCK_ACK:
+		peer->blocked = true;
+		rate_ctr_inc(&peer->ctrg->ctr[GBPROX_PEER_CTR_BLOCKED]);
+		break;
+	case BSSGP_PDUT_BVC_UNBLOCK_ACK:
+		peer->blocked = false;
+		rate_ctr_inc(&peer->ctrg->ctr[GBPROX_PEER_CTR_UNBLOCKED]);
+		break;
+	default:
+		break;
+	}
+	return 0;
+}
+
+/* Send a message to a peer identified by ptp_bvci but using ns_bvci
+ * in the NS hdr */
+static int gbprox_relay2bvci(struct gbproxy_config *cfg, struct msgb *msg, uint16_t ptp_bvci,
+			  uint16_t ns_bvci)
+{
+	struct gbproxy_peer *peer;
+
+	peer = gbproxy_peer_by_bvci(cfg, ptp_bvci);
+	if (!peer) {
+		LOGP(DGPRS, LOGL_ERROR, "BVCI=%u: Cannot find BSS\n",
+			ptp_bvci);
+		rate_ctr_inc(&cfg->ctrg->ctr[GBPROX_GLOB_CTR_INV_BVCI]);
+		return -ENOENT;
+	}
+
+	return gbprox_relay2peer(msg, peer, ns_bvci);
+}
+
+int bssgp_prim_cb(struct osmo_prim_hdr *oph, void *ctx)
+{
+	return 0;
+}
+
+/* Receive an incoming PTP message from a BSS-side NS-VC */
+static int gbprox_rx_ptp_from_bss(struct gbproxy_config *cfg,
+				  struct msgb *msg, uint16_t nsei,
+				  uint16_t nsvci, uint16_t ns_bvci)
+{
+	struct gbproxy_peer *peer;
+	struct bssgp_normal_hdr *bgph = (struct bssgp_normal_hdr *) msgb_bssgph(msg);
+	uint8_t pdu_type = bgph->pdu_type;
+	int rc;
+
+	peer = gbproxy_peer_by_bvci(cfg, ns_bvci);
+	if (!peer) {
+		LOGP(DGPRS, LOGL_NOTICE, "Didn't find peer for "
+		     "BVCI=%u for PTP message from NSVC=%u/NSEI=%u (BSS), "
+		     "discarding message\n",
+		     ns_bvci, nsvci, nsei);
+		return bssgp_tx_status(BSSGP_CAUSE_UNKNOWN_BVCI,
+				       &ns_bvci, msg);
+	}
+
+	check_peer_nsei(peer, nsei);
+
+	rc = gbprox_process_bssgp_ul(cfg, msg, peer);
+	if (!rc)
+		return 0;
+
+	switch (pdu_type) {
+	case BSSGP_PDUT_FLOW_CONTROL_BVC:
+		if (!cfg->route_to_sgsn2)
+			break;
+
+		/* Send a copy to the secondary SGSN */
+		gbprox_relay2sgsn(cfg, msg, ns_bvci, cfg->nsip_sgsn2_nsei);
+		break;
+	default:
+		break;
+	}
+
+
+	return gbprox_relay2sgsn(cfg, msg, ns_bvci, cfg->nsip_sgsn_nsei);
+}
+
+/* Receive an incoming PTP message from a SGSN-side NS-VC */
+static int gbprox_rx_ptp_from_sgsn(struct gbproxy_config *cfg,
+				   struct msgb *msg, uint16_t nsei,
+				   uint16_t nsvci, uint16_t ns_bvci)
+{
+	struct gbproxy_peer *peer;
+	struct bssgp_normal_hdr *bgph = (struct bssgp_normal_hdr *) msgb_bssgph(msg);
+	uint8_t pdu_type = bgph->pdu_type;
+
+	peer = gbproxy_peer_by_bvci(cfg, ns_bvci);
+
+	/* Send status messages before patching */
+
+	if (!peer) {
+		LOGP(DGPRS, LOGL_INFO, "Didn't find peer for "
+		     "BVCI=%u for message from NSVC=%u/NSEI=%u (SGSN)\n",
+		     ns_bvci, nsvci, nsei);
+		rate_ctr_inc(&cfg->ctrg->
+			     ctr[GBPROX_GLOB_CTR_INV_BVCI]);
+		return bssgp_tx_status(BSSGP_CAUSE_UNKNOWN_BVCI,
+				       &ns_bvci, msg);
+	}
+
+	if (peer->blocked) {
+		LOGP(DGPRS, LOGL_NOTICE, "Dropping PDU for "
+		     "blocked BVCI=%u via NSVC=%u/NSEI=%u\n",
+		     ns_bvci, nsvci, nsei);
+		rate_ctr_inc(&peer->ctrg->ctr[GBPROX_PEER_CTR_DROPPED]);
+		return bssgp_tx_status(BSSGP_CAUSE_BVCI_BLOCKED, &ns_bvci, msg);
+	}
+
+	switch (pdu_type) {
+	case BSSGP_PDUT_FLOW_CONTROL_BVC_ACK:
+	case BSSGP_PDUT_BVC_BLOCK_ACK:
+	case BSSGP_PDUT_BVC_UNBLOCK_ACK:
+		if (cfg->route_to_sgsn2 && nsei == cfg->nsip_sgsn2_nsei)
+			/* Hide ACKs from the secondary SGSN, the primary SGSN
+			 * is responsible to send them. */
+			return 0;
+		break;
+	default:
+		break;
+	}
+
+	/* Optionally patch the message */
+	gbprox_process_bssgp_dl(cfg, msg, peer);
+
+	return gbprox_relay2peer(msg, peer, ns_bvci);
+}
+
+/* Receive an incoming signalling message from a BSS-side NS-VC */
+static int gbprox_rx_sig_from_bss(struct gbproxy_config *cfg,
+				  struct msgb *msg, uint16_t nsei,
+				  uint16_t ns_bvci)
+{
+	struct bssgp_normal_hdr *bgph = (struct bssgp_normal_hdr *) msgb_bssgph(msg);
+	struct tlv_parsed tp;
+	uint8_t pdu_type = bgph->pdu_type;
+	int data_len = msgb_bssgp_len(msg) - sizeof(*bgph);
+	struct gbproxy_peer *from_peer = NULL;
+	struct gprs_ra_id raid;
+	int copy_to_sgsn2 = 0;
+	int rc;
+
+	if (ns_bvci != 0 && ns_bvci != 1) {
+		LOGP(DGPRS, LOGL_NOTICE, "NSEI=%u BVCI=%u is not signalling\n",
+			nsei, ns_bvci);
+		return -EINVAL;
+	}
+
+	/* we actually should never see those two for BVCI == 0, but double-check
+	 * just to make sure  */
+	if (pdu_type == BSSGP_PDUT_UL_UNITDATA ||
+	    pdu_type == BSSGP_PDUT_DL_UNITDATA) {
+		LOGP(DGPRS, LOGL_NOTICE, "NSEI=%u UNITDATA not allowed in "
+			"signalling\n", nsei);
+		return -EINVAL;
+	}
+
+	bssgp_tlv_parse(&tp, bgph->data, data_len);
+
+	switch (pdu_type) {
+	case BSSGP_PDUT_SUSPEND:
+	case BSSGP_PDUT_RESUME:
+		/* We implement RAI snooping during SUSPEND/RESUME, since it
+		 * establishes a relationsip between BVCI/peer and the routeing
+		 * area identification.  The snooped information is then used
+		 * for routing the {SUSPEND,RESUME}_[N]ACK back to the correct
+		 * BSSGP */
+		if (!TLVP_PRESENT(&tp, BSSGP_IE_ROUTEING_AREA))
+			goto err_mand_ie;
+		from_peer = gbproxy_peer_by_nsei(cfg, nsei);
+		if (!from_peer)
+			goto err_no_peer;
+		memcpy(from_peer->ra, TLVP_VAL(&tp, BSSGP_IE_ROUTEING_AREA),
+			sizeof(from_peer->ra));
+		gsm48_parse_ra(&raid, from_peer->ra);
+		LOGP(DGPRS, LOGL_INFO, "NSEI=%u BSSGP SUSPEND/RESUME "
+			"RAI snooping: RAI %s behind BVCI=%u\n",
+			nsei, osmo_rai_name(&raid), from_peer->bvci);
+		/* FIXME: This only supports one BSS per RA */
+		break;
+	case BSSGP_PDUT_BVC_RESET:
+		/* If we receive a BVC reset on the signalling endpoint, we
+		 * don't want the SGSN to reset, as the signalling endpoint
+		 * is common for all point-to-point BVCs (and thus all BTS) */
+		if (TLVP_PRESENT(&tp, BSSGP_IE_BVCI)) {
+			uint16_t bvci = ntohs(tlvp_val16_unal(&tp, BSSGP_IE_BVCI));
+			LOGP(DGPRS, LOGL_INFO, "NSEI=%u Rx BVC RESET (BVCI=%u)\n",
+				nsei, bvci);
+			if (bvci == 0) {
+				/* FIXME: only do this if SGSN is alive! */
+				LOGP(DGPRS, LOGL_INFO, "NSEI=%u Tx fake "
+					"BVC RESET ACK of BVCI=0\n", nsei);
+				return bssgp_tx_simple_bvci(BSSGP_PDUT_BVC_RESET_ACK,
+							    nsei, 0, ns_bvci);
+			}
+			from_peer = gbproxy_peer_by_bvci(cfg, bvci);
+			if (!from_peer) {
+				/* if a PTP-BVC is reset, and we don't know that
+				 * PTP-BVCI yet, we should allocate a new peer */
+				LOGP(DGPRS, LOGL_INFO, "Allocationg new peer for BVCI=%u via NSEI=%u\n", bvci, nsei);
+				from_peer = gbproxy_peer_alloc(cfg, bvci);
+				OSMO_ASSERT(from_peer);
+				from_peer->nsei = nsei;
+			}
+
+			if (!check_peer_nsei(from_peer, nsei))
+				from_peer->nsei = nsei;
+
+			if (TLVP_PRESENT(&tp, BSSGP_IE_CELL_ID)) {
+				struct gprs_ra_id raid;
+				/* We have a Cell Identifier present in this
+				 * PDU, this means we can extend our local
+				 * state information about this particular cell
+				 * */
+				memcpy(from_peer->ra,
+					TLVP_VAL(&tp, BSSGP_IE_CELL_ID),
+					sizeof(from_peer->ra));
+				gsm48_parse_ra(&raid, from_peer->ra);
+				LOGP(DGPRS, LOGL_INFO, "NSEI=%u/BVCI=%u Cell ID %s\n",
+				     nsei, bvci, osmo_rai_name(&raid));
+			}
+			if (cfg->route_to_sgsn2)
+				copy_to_sgsn2 = 1;
+		}
+		break;
+	}
+
+	/* Normally, we can simply pass on all signalling messages from BSS to
+	 * SGSN */
+	rc = gbprox_process_bssgp_ul(cfg, msg, from_peer);
+	if (!rc)
+		return 0;
+
+	if (copy_to_sgsn2)
+		gbprox_relay2sgsn(cfg, msg, ns_bvci, cfg->nsip_sgsn2_nsei);
+
+	return gbprox_relay2sgsn(cfg, msg, ns_bvci, cfg->nsip_sgsn_nsei);
+err_no_peer:
+	LOGP(DGPRS, LOGL_ERROR, "NSEI=%u(BSS) cannot find peer based on NSEI\n",
+		nsei);
+	rate_ctr_inc(&cfg->ctrg->ctr[GBPROX_GLOB_CTR_INV_NSEI]);
+	return bssgp_tx_status(BSSGP_CAUSE_INV_MAND_INF, NULL, msg);
+err_mand_ie:
+	LOGP(DGPRS, LOGL_ERROR, "NSEI=%u(BSS) missing mandatory RA IE\n",
+		nsei);
+	rate_ctr_inc(&cfg->ctrg->ctr[GBPROX_GLOB_CTR_PROTO_ERR_BSS]);
+	return bssgp_tx_status(BSSGP_CAUSE_MISSING_MAND_IE, NULL, msg);
+}
+
+/* Receive paging request from SGSN, we need to relay to proper BSS */
+static int gbprox_rx_paging(struct gbproxy_config *cfg, struct msgb *msg, struct tlv_parsed *tp,
+			    uint32_t nsei, uint16_t ns_bvci)
+{
+	struct gbproxy_peer *peer = NULL;
+	int errctr = GBPROX_GLOB_CTR_PROTO_ERR_SGSN;
+
+	LOGP(DGPRS, LOGL_INFO, "NSEI=%u(SGSN) BSSGP PAGING ",
+		nsei);
+	if (TLVP_PRESENT(tp, BSSGP_IE_BVCI)) {
+		uint16_t bvci = ntohs(tlvp_val16_unal(tp, BSSGP_IE_BVCI));
+		LOGPC(DGPRS, LOGL_INFO, "routing by BVCI to peer BVCI=%u\n",
+			bvci);
+		errctr = GBPROX_GLOB_CTR_OTHER_ERR;
+	} else if (TLVP_PRESENT(tp, BSSGP_IE_ROUTEING_AREA)) {
+		peer = gbproxy_peer_by_rai(cfg, TLVP_VAL(tp, BSSGP_IE_ROUTEING_AREA));
+		LOGPC(DGPRS, LOGL_INFO, "routing by RAI to peer BVCI=%u\n",
+			peer ? peer->bvci : -1);
+		errctr = GBPROX_GLOB_CTR_INV_RAI;
+	} else if (TLVP_PRESENT(tp, BSSGP_IE_LOCATION_AREA)) {
+		peer = gbproxy_peer_by_lai(cfg, TLVP_VAL(tp, BSSGP_IE_LOCATION_AREA));
+		LOGPC(DGPRS, LOGL_INFO, "routing by LAI to peer BVCI=%u\n",
+			peer ? peer->bvci : -1);
+		errctr = GBPROX_GLOB_CTR_INV_LAI;
+	} else
+		LOGPC(DGPRS, LOGL_INFO, "\n");
+
+	if (!peer) {
+		LOGP(DGPRS, LOGL_ERROR, "NSEI=%u(SGSN) BSSGP PAGING: "
+			"unable to route, missing IE\n", nsei);
+		rate_ctr_inc(&cfg->ctrg->ctr[errctr]);
+		return -EINVAL;
+	}
+	return gbprox_relay2peer(msg, peer, ns_bvci);
+}
+
+/* Receive an incoming BVC-RESET message from the SGSN */
+static int rx_reset_from_sgsn(struct gbproxy_config *cfg,
+			struct msgb *orig_msg,
+			struct msgb *msg, struct tlv_parsed *tp,
+			uint32_t nsei, uint16_t ns_bvci)
+{
+	struct gbproxy_peer *peer;
+	uint16_t ptp_bvci;
+
+	if (!TLVP_PRESENT(tp, BSSGP_IE_BVCI)) {
+		rate_ctr_inc(&cfg->ctrg->
+			     ctr[GBPROX_GLOB_CTR_PROTO_ERR_SGSN]);
+		return bssgp_tx_status(BSSGP_CAUSE_MISSING_MAND_IE,
+				       NULL, orig_msg);
+	}
+	ptp_bvci = ntohs(tlvp_val16_unal(tp, BSSGP_IE_BVCI));
+
+	if (ptp_bvci >= 2) {
+		/* A reset for a PTP BVC was received, forward it to its
+		 * respective peer */
+		peer = gbproxy_peer_by_bvci(cfg, ptp_bvci);
+		if (!peer) {
+			LOGP(DGPRS, LOGL_ERROR, "NSEI=%u BVCI=%u: Cannot find BSS\n",
+				nsei, ptp_bvci);
+			rate_ctr_inc(&cfg->ctrg->
+				     ctr[GBPROX_GLOB_CTR_INV_BVCI]);
+			return bssgp_tx_status(BSSGP_CAUSE_UNKNOWN_BVCI,
+					       &ptp_bvci, orig_msg);
+		}
+		return gbprox_relay2peer(msg, peer, ns_bvci);
+	}
+
+	/* A reset for the Signalling entity has been received
+	 * from the SGSN.  As the signalling BVCI is shared
+	 * among all the BSS's that we multiplex, it needs to
+	 * be relayed  */
+	llist_for_each_entry(peer, &cfg->bts_peers, list)
+		gbprox_relay2peer(msg, peer, ns_bvci);
+
+	return 0;
+}
+
+/* Receive an incoming signalling message from the SGSN-side NS-VC */
+static int gbprox_rx_sig_from_sgsn(struct gbproxy_config *cfg,
+				struct msgb *orig_msg, uint32_t nsei,
+				uint16_t ns_bvci)
+{
+	struct bssgp_normal_hdr *bgph =
+		(struct bssgp_normal_hdr *) msgb_bssgph(orig_msg);
+	struct tlv_parsed tp;
+	uint8_t pdu_type = bgph->pdu_type;
+	int data_len;
+	struct gbproxy_peer *peer;
+	uint16_t bvci;
+	struct msgb *msg;
+	int rc = 0;
+	int cause;
+
+	if (ns_bvci != 0 && ns_bvci != 1) {
+		LOGP(DGPRS, LOGL_NOTICE, "NSEI=%u(SGSN) BVCI=%u is not "
+			"signalling\n", nsei, ns_bvci);
+		/* FIXME: Send proper error message */
+		return -EINVAL;
+	}
+
+	/* we actually should never see those two for BVCI == 0, but double-check
+	 * just to make sure  */
+	if (pdu_type == BSSGP_PDUT_UL_UNITDATA ||
+	    pdu_type == BSSGP_PDUT_DL_UNITDATA) {
+		LOGP(DGPRS, LOGL_NOTICE, "NSEI=%u(SGSN) UNITDATA not allowed in "
+			"signalling\n", nsei);
+		return bssgp_tx_status(BSSGP_CAUSE_PROTO_ERR_UNSPEC, NULL, orig_msg);
+	}
+
+	msg = bssgp_msgb_copy(orig_msg, "rx_sig_from_sgsn");
+	gbprox_process_bssgp_dl(cfg, msg, NULL);
+	/* Update message info */
+	bgph = (struct bssgp_normal_hdr *) msgb_bssgph(msg);
+	data_len = msgb_bssgp_len(orig_msg) - sizeof(*bgph);
+	rc = bssgp_tlv_parse(&tp, bgph->data, data_len);
+
+	switch (pdu_type) {
+	case BSSGP_PDUT_BVC_RESET:
+		rc = rx_reset_from_sgsn(cfg, msg, orig_msg, &tp, nsei, ns_bvci);
+		break;
+	case BSSGP_PDUT_BVC_RESET_ACK:
+		if (cfg->route_to_sgsn2 && nsei == cfg->nsip_sgsn2_nsei)
+			break;
+		/* fall through */
+	case BSSGP_PDUT_FLUSH_LL:
+		/* simple case: BVCI IE is mandatory */
+		if (!TLVP_PRESENT(&tp, BSSGP_IE_BVCI))
+			goto err_mand_ie;
+		bvci = ntohs(tlvp_val16_unal(&tp, BSSGP_IE_BVCI));
+		rc = gbprox_relay2bvci(cfg, msg, bvci, ns_bvci);
+		break;
+	case BSSGP_PDUT_PAGING_PS:
+	case BSSGP_PDUT_PAGING_CS:
+		/* process the paging request (LAI/RAI lookup) */
+		rc = gbprox_rx_paging(cfg, msg, &tp, nsei, ns_bvci);
+		break;
+	case BSSGP_PDUT_STATUS:
+		/* Some exception has occurred */
+		LOGP(DGPRS, LOGL_NOTICE,
+			"NSEI=%u(SGSN) BSSGP STATUS ", nsei);
+		if (!TLVP_PRESENT(&tp, BSSGP_IE_CAUSE)) {
+			LOGPC(DGPRS, LOGL_NOTICE, "\n");
+			goto err_mand_ie;
+		}
+		cause = *TLVP_VAL(&tp, BSSGP_IE_CAUSE);
+		LOGPC(DGPRS, LOGL_NOTICE,
+			"cause=0x%02x(%s) ", *TLVP_VAL(&tp, BSSGP_IE_CAUSE),
+			bssgp_cause_str(cause));
+		if (TLVP_PRESENT(&tp, BSSGP_IE_BVCI)) {
+			bvci = ntohs(tlvp_val16_unal(&tp, BSSGP_IE_BVCI));
+			LOGPC(DGPRS, LOGL_NOTICE, "BVCI=%u\n", bvci);
+
+			if (cause == BSSGP_CAUSE_UNKNOWN_BVCI)
+				rc = gbprox_relay2bvci(cfg, msg, bvci, ns_bvci);
+		} else
+			LOGPC(DGPRS, LOGL_NOTICE, "\n");
+		break;
+	/* those only exist in the SGSN -> BSS direction */
+	case BSSGP_PDUT_SUSPEND_ACK:
+	case BSSGP_PDUT_SUSPEND_NACK:
+	case BSSGP_PDUT_RESUME_ACK:
+	case BSSGP_PDUT_RESUME_NACK:
+		/* RAI IE is mandatory */
+		if (!TLVP_PRESENT(&tp, BSSGP_IE_ROUTEING_AREA))
+			goto err_mand_ie;
+		peer = gbproxy_peer_by_rai(cfg, TLVP_VAL(&tp, BSSGP_IE_ROUTEING_AREA));
+		if (!peer)
+			goto err_no_peer;
+		rc = gbprox_relay2peer(msg, peer, ns_bvci);
+		break;
+	case BSSGP_PDUT_BVC_BLOCK_ACK:
+	case BSSGP_PDUT_BVC_UNBLOCK_ACK:
+		if (!TLVP_PRESENT(&tp, BSSGP_IE_BVCI))
+			goto err_mand_ie;
+		bvci = ntohs(tlvp_val16_unal(&tp, BSSGP_IE_BVCI));
+		if (bvci == 0) {
+			LOGP(DGPRS, LOGL_NOTICE, "NSEI=%u(SGSN) BSSGP "
+			     "%sBLOCK_ACK for signalling BVCI ?!?\n", nsei,
+			     pdu_type == BSSGP_PDUT_BVC_UNBLOCK_ACK ? "UN":"");
+			/* should we send STATUS ? */
+			rate_ctr_inc(&cfg->ctrg->
+				     ctr[GBPROX_GLOB_CTR_INV_BVCI]);
+		} else {
+			/* Mark BVC as (un)blocked */
+			block_unblock_peer(cfg, bvci, pdu_type);
+		}
+		rc = gbprox_relay2bvci(cfg, msg, bvci, ns_bvci);
+		break;
+	case BSSGP_PDUT_SGSN_INVOKE_TRACE:
+		LOGP(DGPRS, LOGL_ERROR,
+		     "NSEI=%u(SGSN) BSSGP INVOKE TRACE not supported\n",nsei);
+		rate_ctr_inc(&cfg->ctrg->
+			     ctr[GBPROX_GLOB_CTR_NOT_SUPPORTED_SGSN]);
+		rc = bssgp_tx_status(BSSGP_CAUSE_PDU_INCOMP_FEAT, NULL, orig_msg);
+		break;
+	default:
+		LOGP(DGPRS, LOGL_NOTICE, "BSSGP PDU type %s not supported\n", bssgp_pdu_str(pdu_type));
+		rate_ctr_inc(&cfg->ctrg->
+			     ctr[GBPROX_GLOB_CTR_PROTO_ERR_SGSN]);
+		rc = bssgp_tx_status(BSSGP_CAUSE_PROTO_ERR_UNSPEC, NULL, orig_msg);
+		break;
+	}
+
+	msgb_free(msg);
+
+	return rc;
+err_mand_ie:
+	LOGP(DGPRS, LOGL_ERROR, "NSEI=%u(SGSN) missing mandatory IE\n",
+		nsei);
+	rate_ctr_inc(&cfg->ctrg->
+		     ctr[GBPROX_GLOB_CTR_PROTO_ERR_SGSN]);
+	msgb_free(msg);
+	return bssgp_tx_status(BSSGP_CAUSE_MISSING_MAND_IE, NULL, orig_msg);
+err_no_peer:
+	LOGP(DGPRS, LOGL_ERROR, "NSEI=%u(SGSN) cannot find peer based on RAI\n",
+		nsei);
+	rate_ctr_inc(&cfg->ctrg-> ctr[GBPROX_GLOB_CTR_INV_RAI]);
+	msgb_free(msg);
+	return bssgp_tx_status(BSSGP_CAUSE_INV_MAND_INF, NULL, orig_msg);
+}
+
+static int gbproxy_is_sgsn_nsei(struct gbproxy_config *cfg, uint16_t nsei)
+{
+	return nsei == cfg->nsip_sgsn_nsei ||
+		(cfg->route_to_sgsn2 && nsei == cfg->nsip_sgsn2_nsei);
+}
+
+/* Main input function for Gb proxy */
+int gbprox_rcvmsg(struct gbproxy_config *cfg, struct msgb *msg, uint16_t nsei,
+		uint16_t ns_bvci, uint16_t nsvci)
+{
+	int rc;
+	int remote_end_is_sgsn = gbproxy_is_sgsn_nsei(cfg, nsei);
+
+	/* Only BVCI=0 messages need special treatment */
+	if (ns_bvci == 0 || ns_bvci == 1) {
+		if (remote_end_is_sgsn)
+			rc = gbprox_rx_sig_from_sgsn(cfg, msg, nsei, ns_bvci);
+		else
+			rc = gbprox_rx_sig_from_bss(cfg, msg, nsei, ns_bvci);
+	} else {
+		/* All other BVCI are PTP */
+		if (remote_end_is_sgsn)
+			rc = gbprox_rx_ptp_from_sgsn(cfg, msg, nsei, nsvci,
+						     ns_bvci);
+		else
+			rc = gbprox_rx_ptp_from_bss(cfg, msg, nsei, nsvci,
+						    ns_bvci);
+	}
+
+	return rc;
+}
+
+int gbprox_reset_persistent_nsvcs(struct gprs_ns_inst *nsi)
+{
+	struct gprs_nsvc *nsvc;
+
+	llist_for_each_entry(nsvc, &nsi->gprs_nsvcs, list) {
+		if (!nsvc->persistent)
+			continue;
+		gprs_nsvc_reset(nsvc, NS_CAUSE_OM_INTERVENTION);
+	}
+	return 0;
+}
+
+/* Signal handler for signals from NS layer */
+int gbprox_signal(unsigned int subsys, unsigned int signal,
+		  void *handler_data, void *signal_data)
+{
+	struct gbproxy_config *cfg = handler_data;
+	struct ns_signal_data *nssd = signal_data;
+	struct gprs_nsvc *nsvc = nssd->nsvc;
+	struct gbproxy_peer *peer;
+	int remote_end_is_sgsn = gbproxy_is_sgsn_nsei(cfg, nsvc->nsei);
+
+	if (subsys != SS_L_NS)
+		return 0;
+
+	if (signal == S_NS_RESET && remote_end_is_sgsn) {
+		/* We have received a NS-RESET from the NSEI and NSVC
+		 * of the SGSN.  This might happen with SGSN that start
+		 * their own NS-RESET procedure without waiting for our
+		 * NS-RESET */
+		nsvc->remote_end_is_sgsn = 1;
+	}
+
+	if (signal == S_NS_ALIVE_EXP && nsvc->remote_end_is_sgsn) {
+		LOGP(DGPRS, LOGL_NOTICE, "Tns alive expired too often, "
+			"re-starting RESET procedure\n");
+		rate_ctr_inc(&cfg->ctrg->
+			     ctr[GBPROX_GLOB_CTR_RESTART_RESET_SGSN]);
+		gprs_ns_nsip_connect(nsvc->nsi, &nsvc->ip.bts_addr,
+				  nsvc->nsei, nsvc->nsvci);
+	}
+
+	if (!nsvc->remote_end_is_sgsn) {
+		/* from BSS to SGSN */
+		peer = gbproxy_peer_by_nsei(cfg, nsvc->nsei);
+		if (!peer) {
+			LOGP(DGPRS, LOGL_NOTICE, "signal '%s' for unknown peer NSEI=%u/NSVCI=%u\n",
+			     get_value_string(gprs_ns_signal_ns_names, signal), nsvc->nsei, nsvc->nsvci);
+			return 0;
+		}
+		switch (signal) {
+		case S_NS_RESET:
+		case S_NS_BLOCK:
+			if (!peer->blocked)
+				break;
+			LOGP(DGPRS, LOGL_NOTICE, "Converting '%s' from NSEI=%u/NSVCI=%u into BSSGP_BVC_BLOCK to SGSN\n",
+			     get_value_string(gprs_ns_signal_ns_names, signal), nsvc->nsei, nsvc->nsvci);
+			bssgp_tx_simple_bvci(BSSGP_PDUT_BVC_BLOCK, nsvc->nsei,
+					     peer->bvci, 0);
+			break;
+		}
+	} else {
+		/* Forward this message to all NS-VC to BSS */
+		struct gprs_ns_inst *nsi = cfg->nsi;
+		struct gprs_nsvc *next_nsvc;
+
+		llist_for_each_entry(next_nsvc, &nsi->gprs_nsvcs, list) {
+			if (next_nsvc->remote_end_is_sgsn)
+				continue;
+
+			/* Note that the following does not start the full
+			 * procedures including timer based retransmissions. */
+			switch (signal) {
+			case S_NS_RESET:
+				gprs_ns_tx_reset(next_nsvc, nssd->cause);
+				break;
+			case S_NS_BLOCK:
+				gprs_ns_tx_block(next_nsvc, nssd->cause);
+				break;
+			case S_NS_UNBLOCK:
+				gprs_ns_tx_unblock(next_nsvc);
+				break;
+			}
+		}
+	}
+	return 0;
+}
+
+void gbprox_reset(struct gbproxy_config *cfg)
+{
+	struct gbproxy_peer *peer, *tmp;
+
+	llist_for_each_entry_safe(peer, tmp, &cfg->bts_peers, list)
+		gbproxy_peer_free(peer);
+
+	rate_ctr_group_free(cfg->ctrg);
+	gbproxy_init_config(cfg);
+}
+
+int gbproxy_init_config(struct gbproxy_config *cfg)
+{
+	struct timespec tp;
+
+	INIT_LLIST_HEAD(&cfg->bts_peers);
+	cfg->ctrg = rate_ctr_group_alloc(tall_sgsn_ctx, &global_ctrg_desc, 0);
+	if (!cfg->ctrg) {
+		LOGP(DGPRS, LOGL_ERROR, "Cannot allocate global counter group!\n");
+		return -1;
+	}
+	osmo_clock_gettime(CLOCK_REALTIME, &tp);
+
+	return 0;
+}
diff --git a/src/gb_proxy_ctrl.c b/src/gb_proxy_ctrl.c
new file mode 100644
index 0000000..4b7c2f4
--- /dev/null
+++ b/src/gb_proxy_ctrl.c
@@ -0,0 +1,98 @@
+/* Control Interface Implementation for the Gb-proxy */
+/*
+ * (C) 2018 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ * All Rights Reserved
+ *
+ * Author: Daniel Willmann
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <osmocom/core/talloc.h>
+
+
+#include <osmocom/gprs/gprs_bssgp.h>
+#include <osmocom/gprs/gprs_ns.h>
+
+#include <osmocom/ctrl/control_if.h>
+#include <osmocom/ctrl/control_cmd.h>
+#include <osmocom/sgsn/gb_proxy.h>
+#include <osmocom/sgsn/debug.h>
+
+extern vector ctrl_node_vec;
+
+static int get_nsvc_state(struct ctrl_cmd *cmd, void *data)
+{
+	struct gbproxy_config *cfg = data;
+	struct gprs_ns_inst *nsi = cfg->nsi;
+	struct gprs_nsvc *nsvc;
+
+	cmd->reply = talloc_strdup(cmd, "");
+
+	llist_for_each_entry(nsvc, &nsi->gprs_nsvcs, list) {
+		if (nsvc == nsi->unknown_nsvc)
+			continue;
+
+		cmd->reply = gprs_nsvc_state_append(cmd->reply, nsvc);
+	}
+
+	return CTRL_CMD_REPLY;
+}
+
+CTRL_CMD_DEFINE_RO(nsvc_state, "nsvc-state");
+
+static int get_gbproxy_state(struct ctrl_cmd *cmd, void *data)
+{
+	struct gbproxy_config *cfg = data;
+	struct gbproxy_peer *peer;
+
+	cmd->reply = talloc_strdup(cmd, "");
+
+	llist_for_each_entry(peer, &cfg->bts_peers, list) {
+		struct gprs_ra_id raid;
+		gsm48_parse_ra(&raid, peer->ra);
+
+		cmd->reply = talloc_asprintf_append(cmd->reply, "%u,%u,%u,%u,%u,%u,%s\n",
+				peer->nsei, peer->bvci,
+				raid.mcc, raid.mnc,
+				raid.lac, raid.rac,
+				peer->blocked ? "BLOCKED" : "UNBLOCKED");
+	}
+
+	return CTRL_CMD_REPLY;
+}
+
+CTRL_CMD_DEFINE_RO(gbproxy_state, "gbproxy-state");
+
+static int get_num_peers(struct ctrl_cmd *cmd, void *data)
+{
+	struct gbproxy_config *cfg = data;
+
+	cmd->reply = talloc_strdup(cmd, "");
+	cmd->reply = talloc_asprintf_append(cmd->reply, "%u", llist_count(&cfg->bts_peers));
+
+	return CTRL_CMD_REPLY;
+}
+CTRL_CMD_DEFINE_RO(num_peers, "number-of-peers");
+
+int gb_ctrl_cmds_install(void)
+{
+	int rc = 0;
+	rc |= ctrl_cmd_install(CTRL_NODE_ROOT, &cmd_nsvc_state);
+	rc |= ctrl_cmd_install(CTRL_NODE_ROOT, &cmd_gbproxy_state);
+	rc |= ctrl_cmd_install(CTRL_NODE_ROOT, &cmd_num_peers);
+
+	return rc;
+}
diff --git a/src/gb_proxy_main.c b/src/gb_proxy_main.c
new file mode 100644
index 0000000..4319fda
--- /dev/null
+++ b/src/gb_proxy_main.c
@@ -0,0 +1,393 @@
+/* NS-over-IP proxy */
+
+/* (C) 2010 by Harald Welte <laforge@gnumonks.org>
+ * (C) 2010 by On-Waves
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <getopt.h>
+#include <errno.h>
+#include <signal.h>
+#include <sys/fcntl.h>
+#include <sys/stat.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+
+#include <osmocom/core/application.h>
+#include <osmocom/core/talloc.h>
+#include <osmocom/core/select.h>
+#include <osmocom/core/rate_ctr.h>
+#include <osmocom/core/stats.h>
+
+#include <osmocom/gprs/gprs_ns.h>
+#include <osmocom/gprs/gprs_bssgp.h>
+
+#include <osmocom/sgsn/signal.h>
+#include <osmocom/sgsn/debug.h>
+#include <osmocom/sgsn/vty.h>
+#include <osmocom/sgsn/gb_proxy.h>
+
+#include <osmocom/ctrl/control_vty.h>
+#include <osmocom/ctrl/control_if.h>
+#include <osmocom/ctrl/ports.h>
+
+#include <osmocom/vty/command.h>
+#include <osmocom/vty/telnet_interface.h>
+#include <osmocom/vty/logging.h>
+#include <osmocom/vty/stats.h>
+#include <osmocom/vty/ports.h>
+#include <osmocom/vty/misc.h>
+
+#include "../../bscconfig.h"
+
+#define _GNU_SOURCE
+#include <getopt.h>
+
+void *tall_sgsn_ctx;
+
+const char *openbsc_copyright =
+	"Copyright (C) 2010 Harald Welte and On-Waves\r\n"
+	"License AGPLv3+: GNU AGPL version 3 or later <http://gnu.org/licenses/agpl-3.0.html>\r\n"
+	"This is free software: you are free to change and redistribute it.\r\n"
+	"There is NO WARRANTY, to the extent permitted by law.\r\n";
+
+#define CONFIG_FILE_DEFAULT "osmo-gbproxy.cfg"
+#define CONFIG_FILE_LEGACY "osmo_gbproxy.cfg"
+
+static char *config_file = NULL;
+struct gbproxy_config *gbcfg;
+static int daemonize = 0;
+
+/* Pointer to the SGSN peer */
+extern struct gbprox_peer *gbprox_peer_sgsn;
+
+/* call-back function for the NS protocol */
+static int proxy_ns_cb(enum gprs_ns_evt event, struct gprs_nsvc *nsvc,
+		      struct msgb *msg, uint16_t bvci)
+{
+	int rc = 0;
+
+	switch (event) {
+	case GPRS_NS_EVT_UNIT_DATA:
+		rc = gbprox_rcvmsg(gbcfg, msg, nsvc->nsei, bvci, nsvc->nsvci);
+		break;
+	default:
+		LOGP(DGPRS, LOGL_ERROR, "SGSN: Unknown event %u from NS\n", event);
+		if (msg)
+			msgb_free(msg);
+		rc = -EIO;
+		break;
+	}
+	return rc;
+}
+
+static void signal_handler(int signal)
+{
+	fprintf(stdout, "signal %u received\n", signal);
+
+	switch (signal) {
+	case SIGINT:
+	case SIGTERM:
+		osmo_signal_dispatch(SS_L_GLOBAL, S_L_GLOBAL_SHUTDOWN, NULL);
+		sleep(1);
+		exit(0);
+		break;
+	case SIGABRT:
+		/* in case of abort, we want to obtain a talloc report
+		 * and then return to the caller, who will abort the process */
+	case SIGUSR1:
+		talloc_report(tall_vty_ctx, stderr);
+		talloc_report_full(tall_sgsn_ctx, stderr);
+		break;
+	case SIGUSR2:
+		talloc_report_full(tall_vty_ctx, stderr);
+		break;
+	default:
+		break;
+	}
+}
+
+static void print_usage()
+{
+	printf("Usage: bsc_hack\n");
+}
+
+static void print_help()
+{
+	printf("  Some useful help...\n");
+	printf("  -h --help this text\n");
+	printf("  -d option --debug=DNS:DGPRS,0:0 enable debugging\n");
+	printf("  -D --daemonize Fork the process into a background daemon\n");
+	printf("  -c --config-file filename The config file to use [%s]\n", CONFIG_FILE_DEFAULT);
+	printf("  -s --disable-color\n");
+	printf("  -T --timestamp Prefix every log line with a timestamp\n");
+	printf("  -V --version. Print the version.\n");
+	printf("  -e --log-level number. Set a global loglevel.\n");
+}
+
+static void handle_options(int argc, char **argv)
+{
+	while (1) {
+		int option_index = 0, c;
+		static struct option long_options[] = {
+			{ "help", 0, 0, 'h' },
+			{ "debug", 1, 0, 'd' },
+			{ "daemonize", 0, 0, 'D' },
+			{ "config-file", 1, 0, 'c' },
+			{ "disable-color", 0, 0, 's' },
+			{ "timestamp", 0, 0, 'T' },
+			{ "version", 0, 0, 'V' },
+			{ "log-level", 1, 0, 'e' },
+			{ 0, 0, 0, 0 }
+		};
+
+		c = getopt_long(argc, argv, "hd:Dc:sTVe:",
+				long_options, &option_index);
+		if (c == -1)
+			break;
+
+		switch (c) {
+		case 'h':
+			print_usage();
+			print_help();
+			exit(0);
+		case 's':
+			log_set_use_color(osmo_stderr_target, 0);
+			break;
+		case 'd':
+			log_parse_category_mask(osmo_stderr_target, optarg);
+			break;
+		case 'D':
+			daemonize = 1;
+			break;
+		case 'c':
+			config_file = optarg;
+			break;
+		case 'T':
+			log_set_print_timestamp(osmo_stderr_target, 1);
+			break;
+		case 'e':
+			log_set_log_level(osmo_stderr_target, atoi(optarg));
+			break;
+		case 'V':
+			print_version(1);
+			exit(0);
+			break;
+		default:
+			break;
+		}
+	}
+}
+
+int gbproxy_vty_is_config_node(struct vty *vty, int node)
+{
+        switch (node) {
+        /* add items that are not config */
+        case CONFIG_NODE:
+                return 0;
+
+        default:
+                return 1;
+        }
+}
+
+int gbproxy_vty_go_parent(struct vty *vty)
+{
+        switch (vty->node) {
+        case GBPROXY_NODE:
+        default:
+                if (gbproxy_vty_is_config_node(vty, vty->node))
+                        vty->node = CONFIG_NODE;
+                else
+                        vty->node = ENABLE_NODE;
+
+                vty->index = NULL;
+        }
+
+        return vty->node;
+}
+
+static struct vty_app_info vty_info = {
+	.name 		= "OsmoGbProxy",
+	.version	= PACKAGE_VERSION,
+	.go_parent_cb	= gbproxy_vty_go_parent,
+	.is_config_node	= gbproxy_vty_is_config_node,
+};
+
+/* default categories */
+static struct log_info_cat gprs_categories[] = {
+	[DGPRS] = {
+		.name = "DGPRS",
+		.description = "GPRS Packet Service",
+		.enabled = 1, .loglevel = LOGL_DEBUG,
+	},
+	[DNS] = {
+		.name = "DNS",
+		.description = "GPRS Network Service (NS)",
+		.enabled = 1, .loglevel = LOGL_INFO,
+	},
+	[DBSSGP] = {
+		.name = "DBSSGP",
+		.description = "GPRS BSS Gateway Protocol (BSSGP)",
+		.enabled = 1, .loglevel = LOGL_DEBUG,
+	},
+};
+
+static const struct log_info gprs_log_info = {
+	.filter_fn = gprs_log_filter_fn,
+	.cat = gprs_categories,
+	.num_cat = ARRAY_SIZE(gprs_categories),
+};
+
+static bool file_exists(const char *path)
+{
+	struct stat sb;
+	return stat(path, &sb) ? false : true;
+}
+
+int main(int argc, char **argv)
+{
+	int rc;
+	struct ctrl_handle *ctrl;
+
+	tall_sgsn_ctx = talloc_named_const(NULL, 0, "nsip_proxy");
+	msgb_talloc_ctx_init(tall_sgsn_ctx, 0);
+	vty_info.tall_ctx = tall_sgsn_ctx;
+
+	signal(SIGINT, &signal_handler);
+	signal(SIGTERM, &signal_handler);
+	signal(SIGABRT, &signal_handler);
+	signal(SIGUSR1, &signal_handler);
+	signal(SIGUSR2, &signal_handler);
+	osmo_init_ignore_signals();
+
+	osmo_init_logging2(tall_sgsn_ctx, &gprs_log_info);
+
+	vty_info.copyright = openbsc_copyright;
+	vty_init(&vty_info);
+	logging_vty_add_cmds();
+	osmo_talloc_vty_add_cmds();
+	osmo_stats_vty_add_cmds();
+	gbproxy_vty_init();
+
+	handle_options(argc, argv);
+
+	/* Backwards compatibility: for years, the default config file name was
+	 * osmo_gbproxy.cfg. All other Osmocom programs use osmo-*.cfg with a
+	 * dash. To be able to use the new config file name without breaking
+	 * previous setups that might rely on the legacy default config file
+	 * name, we need to look for the old config file if no -c option was
+	 * passed AND no file exists with the new default file name. */
+	if (!config_file) {
+		/* No -c option was passed */
+		if (file_exists(CONFIG_FILE_LEGACY)
+		    && !file_exists(CONFIG_FILE_DEFAULT))
+			config_file = CONFIG_FILE_LEGACY;
+		else
+			config_file = CONFIG_FILE_DEFAULT;
+	}
+
+	rate_ctr_init(tall_sgsn_ctx);
+	osmo_stats_init(tall_sgsn_ctx);
+
+	bssgp_nsi = gprs_ns_instantiate(&proxy_ns_cb, tall_sgsn_ctx);
+	if (!bssgp_nsi) {
+		LOGP(DGPRS, LOGL_ERROR, "Unable to instantiate NS\n");
+		exit(1);
+	}
+
+	gbcfg = talloc_zero(tall_sgsn_ctx, struct gbproxy_config);
+	if (!gbcfg) {
+		LOGP(DGPRS, LOGL_FATAL, "Unable to allocate config\n");
+		exit(1);
+	}
+	gbproxy_init_config(gbcfg);
+	gbcfg->nsi = bssgp_nsi;
+	gprs_ns_vty_init(bssgp_nsi);
+	gprs_ns_set_log_ss(DNS);
+	bssgp_set_log_ss(DBSSGP);
+	osmo_signal_register_handler(SS_L_NS, &gbprox_signal, gbcfg);
+
+	rc = gbproxy_parse_config(config_file, gbcfg);
+	if (rc < 0) {
+		LOGP(DGPRS, LOGL_FATAL, "Cannot parse config file '%s'\n", config_file);
+		exit(2);
+	}
+
+	/* start telnet after reading config for vty_get_bind_addr() */
+	rc = telnet_init_dynif(tall_sgsn_ctx, NULL,
+			       vty_get_bind_addr(), OSMO_VTY_PORT_GBPROXY);
+	if (rc < 0)
+		exit(1);
+
+	/* Start control interface after getting config for
+	 * ctrl_vty_get_bind_addr() */
+	ctrl = ctrl_interface_setup_dynip(gbcfg, ctrl_vty_get_bind_addr(), OSMO_CTRL_PORT_GBPROXY, NULL);
+	if (!ctrl) {
+		LOGP(DGPRS, LOGL_FATAL, "Failed to create CTRL interface.\n");
+		exit(1);
+	}
+
+	if (gb_ctrl_cmds_install() != 0) {
+		LOGP(DGPRS, LOGL_FATAL, "Failed to install CTRL commands.\n");
+		exit(1);
+	}
+
+	if (!gprs_nsvc_by_nsei(gbcfg->nsi, gbcfg->nsip_sgsn_nsei)) {
+		LOGP(DGPRS, LOGL_FATAL, "You cannot proxy to NSEI %u "
+			"without creating that NSEI before\n",
+			gbcfg->nsip_sgsn_nsei);
+		exit(2);
+	}
+
+	rc = gprs_ns_nsip_listen(bssgp_nsi);
+	if (rc < 0) {
+		LOGP(DGPRS, LOGL_FATAL, "Cannot bind/listen on NSIP socket\n");
+		exit(2);
+	}
+
+	rc = gprs_ns_frgre_listen(bssgp_nsi);
+	if (rc < 0) {
+		LOGP(DGPRS, LOGL_FATAL, "Cannot bind/listen GRE "
+			"socket. Do you have CAP_NET_RAW?\n");
+		exit(2);
+	}
+
+	if (daemonize) {
+		rc = osmo_daemonize();
+		if (rc < 0) {
+			perror("Error during daemonize");
+			exit(1);
+		}
+	}
+
+	/* Reset all the persistent NS-VCs that we've read from the config */
+	gbprox_reset_persistent_nsvcs(bssgp_nsi);
+
+	while (1) {
+		rc = osmo_select_main(0);
+		if (rc < 0)
+			exit(3);
+	}
+
+	exit(0);
+}
diff --git a/src/gb_proxy_patch.c b/src/gb_proxy_patch.c
new file mode 100644
index 0000000..6235b04
--- /dev/null
+++ b/src/gb_proxy_patch.c
@@ -0,0 +1,465 @@
+/* Gb-proxy message patching */
+
+/* (C) 2014 by On-Waves
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <osmocom/sgsn/gb_proxy.h>
+
+#include <osmocom/sgsn/gprs_utils.h>
+#include <osmocom/sgsn/gprs_gb_parse.h>
+
+#include <osmocom/sgsn/debug.h>
+
+#include <osmocom/gprs/protocol/gsm_08_18.h>
+#include <osmocom/core/rate_ctr.h>
+#include <osmocom/gsm/apn.h>
+
+extern void *tall_sgsn_ctx;
+
+/* patch RA identifier in place */
+static void gbproxy_patch_raid(struct gsm48_ra_id *raid_enc, struct gbproxy_peer *peer,
+			       int to_bss, const char *log_text)
+{
+	struct gbproxy_patch_state *state = &peer->patch_state;
+	struct osmo_plmn_id old_plmn;
+	struct gprs_ra_id raid;
+	enum gbproxy_peer_ctr counter =
+		to_bss ?
+		GBPROX_PEER_CTR_RAID_PATCHED_SGSN :
+		GBPROX_PEER_CTR_RAID_PATCHED_BSS;
+
+	if (!state->local_plmn.mcc || !state->local_plmn.mnc)
+		return;
+
+	gsm48_parse_ra(&raid, (uint8_t *)raid_enc);
+
+	old_plmn = (struct osmo_plmn_id){
+		.mcc = raid.mcc,
+		.mnc = raid.mnc,
+		.mnc_3_digits = raid.mnc_3_digits,
+	};
+
+	if (!to_bss) {
+		/* BSS -> SGSN */
+		if (state->local_plmn.mcc)
+			raid.mcc = peer->cfg->core_plmn.mcc;
+
+		if (state->local_plmn.mnc) {
+			raid.mnc = peer->cfg->core_plmn.mnc;
+			raid.mnc_3_digits = peer->cfg->core_plmn.mnc_3_digits;
+		}
+	} else {
+		/* SGSN -> BSS */
+		if (state->local_plmn.mcc)
+			raid.mcc = state->local_plmn.mcc;
+
+		if (state->local_plmn.mnc) {
+			raid.mnc = state->local_plmn.mnc;
+			raid.mnc_3_digits = state->local_plmn.mnc_3_digits;
+		}
+	}
+
+	LOGP(DGPRS, LOGL_DEBUG,
+	     "Patching %s to %s: "
+	     "%s-%d-%d -> %s\n",
+	     log_text,
+	     to_bss ? "BSS" : "SGSN",
+	     osmo_plmn_name(&old_plmn), raid.lac, raid.rac,
+	     osmo_rai_name(&raid));
+
+	gsm48_encode_ra(raid_enc, &raid);
+	rate_ctr_inc(&peer->ctrg->ctr[counter]);
+}
+
+static void gbproxy_patch_apn_ie(struct msgb *msg,
+				 uint8_t *apn_ie, size_t apn_ie_len,
+				 struct gbproxy_peer *peer,
+				 size_t *new_apn_ie_len, const char *log_text)
+{
+	struct apn_ie_hdr {
+		uint8_t iei;
+		uint8_t apn_len;
+		uint8_t apn[0];
+	} *hdr = (void *)apn_ie;
+
+	size_t apn_len = hdr->apn_len;
+	uint8_t *apn = hdr->apn;
+
+	OSMO_ASSERT(apn_ie_len == apn_len + sizeof(struct apn_ie_hdr));
+	OSMO_ASSERT(apn_ie_len > 2 && apn_ie_len <= 102);
+
+	if (peer->cfg->core_apn_size == 0) {
+		char str1[110];
+		/* Remove the IE */
+		LOGP(DGPRS, LOGL_DEBUG,
+		     "Patching %s to SGSN: Removing APN '%s'\n",
+		     log_text,
+		     osmo_apn_to_str(str1, apn, apn_len));
+
+		*new_apn_ie_len = 0;
+		msgb_resize_area(msg, apn_ie, apn_ie_len, 0);
+	} else {
+		/* Resize the IE */
+		char str1[110];
+		char str2[110];
+
+		OSMO_ASSERT(peer->cfg->core_apn_size <= 100);
+
+		LOGP(DGPRS, LOGL_DEBUG,
+		     "Patching %s to SGSN: "
+		     "Replacing APN '%s' -> '%s'\n",
+		     log_text,
+		     osmo_apn_to_str(str1, apn, apn_len),
+		     osmo_apn_to_str(str2, peer->cfg->core_apn,
+				       peer->cfg->core_apn_size));
+
+		*new_apn_ie_len = peer->cfg->core_apn_size + 2;
+		msgb_resize_area(msg, apn, apn_len, peer->cfg->core_apn_size);
+		memcpy(apn, peer->cfg->core_apn, peer->cfg->core_apn_size);
+		hdr->apn_len = peer->cfg->core_apn_size;
+	}
+
+	rate_ctr_inc(&peer->ctrg->ctr[GBPROX_PEER_CTR_APN_PATCHED]);
+}
+
+static int gbproxy_patch_tlli(uint8_t *tlli_enc,
+			      struct gbproxy_peer *peer,
+			      uint32_t new_tlli,
+			      int to_bss, const char *log_text)
+{
+	uint32_t tlli_be;
+	uint32_t tlli;
+	enum gbproxy_peer_ctr counter =
+		to_bss ?
+		GBPROX_PEER_CTR_TLLI_PATCHED_SGSN :
+		GBPROX_PEER_CTR_TLLI_PATCHED_BSS;
+
+	memcpy(&tlli_be, tlli_enc, sizeof(tlli_be));
+	tlli = ntohl(tlli_be);
+
+	if (tlli == new_tlli)
+		return 0;
+
+	LOGP(DGPRS, LOGL_DEBUG,
+	     "Patching %ss: "
+	     "Replacing %08x -> %08x\n",
+	     log_text, tlli, new_tlli);
+
+	tlli_be = htonl(new_tlli);
+	memcpy(tlli_enc, &tlli_be, sizeof(tlli_be));
+
+	rate_ctr_inc(&peer->ctrg->ctr[counter]);
+
+	return 1;
+}
+
+static int gbproxy_patch_ptmsi(uint8_t *ptmsi_enc,
+			       struct gbproxy_peer *peer,
+			       uint32_t new_ptmsi,
+			       int to_bss, const char *log_text)
+{
+	uint32_t ptmsi_be;
+	uint32_t ptmsi;
+	enum gbproxy_peer_ctr counter =
+		to_bss ?
+		GBPROX_PEER_CTR_PTMSI_PATCHED_SGSN :
+		GBPROX_PEER_CTR_PTMSI_PATCHED_BSS;
+	memcpy(&ptmsi_be, ptmsi_enc, sizeof(ptmsi_be));
+	ptmsi = ntohl(ptmsi_be);
+
+	if (ptmsi == new_ptmsi)
+		return 0;
+
+	LOGP(DGPRS, LOGL_DEBUG,
+	     "Patching %ss: "
+	     "Replacing %08x -> %08x\n",
+	     log_text, ptmsi, new_ptmsi);
+
+	ptmsi_be = htonl(new_ptmsi);
+	memcpy(ptmsi_enc, &ptmsi_be, sizeof(ptmsi_be));
+
+	rate_ctr_inc(&peer->ctrg->ctr[counter]);
+
+	return 1;
+}
+
+int gbproxy_patch_llc(struct msgb *msg, uint8_t *llc, size_t llc_len,
+		     struct gbproxy_peer *peer,
+		     struct gbproxy_link_info *link_info, int *len_change,
+		     struct gprs_gb_parse_context *parse_ctx)
+{
+	struct gprs_llc_hdr_parsed *ghp = &parse_ctx->llc_hdr_parsed;
+	int have_patched = 0;
+	int fcs;
+	struct gbproxy_config *cfg = peer->cfg;
+
+	if (parse_ctx->ptmsi_enc && link_info &&
+	    !parse_ctx->old_raid_is_foreign && peer->cfg->patch_ptmsi) {
+		uint32_t ptmsi;
+		if (parse_ctx->to_bss)
+			ptmsi = link_info->tlli.ptmsi;
+		else
+			ptmsi = link_info->sgsn_tlli.ptmsi;
+
+		if (ptmsi != GSM_RESERVED_TMSI) {
+			if (gbproxy_patch_ptmsi(parse_ctx->ptmsi_enc, peer,
+						ptmsi, parse_ctx->to_bss, "P-TMSI"))
+				have_patched = 1;
+		} else {
+			/* TODO: invalidate old RAI if present (see below) */
+		}
+	}
+
+	if (parse_ctx->new_ptmsi_enc && link_info && cfg->patch_ptmsi) {
+		uint32_t ptmsi;
+		if (parse_ctx->to_bss)
+			ptmsi = link_info->tlli.ptmsi;
+		else
+			ptmsi = link_info->sgsn_tlli.ptmsi;
+
+		OSMO_ASSERT(ptmsi);
+		if (gbproxy_patch_ptmsi(parse_ctx->new_ptmsi_enc, peer,
+					ptmsi, parse_ctx->to_bss, "new P-TMSI"))
+			have_patched = 1;
+	}
+
+	if (parse_ctx->raid_enc) {
+		gbproxy_patch_raid((struct gsm48_ra_id *)parse_ctx->raid_enc, peer, parse_ctx->to_bss,
+				   parse_ctx->llc_msg_name);
+		have_patched = 1;
+	}
+
+	if (parse_ctx->old_raid_enc && !parse_ctx->old_raid_is_foreign) {
+		/* TODO: Patch to invalid if P-TMSI unknown. */
+		gbproxy_patch_raid((struct gsm48_ra_id *)parse_ctx->old_raid_enc, peer, parse_ctx->to_bss,
+				   parse_ctx->llc_msg_name);
+		have_patched = 1;
+	}
+
+	if (parse_ctx->apn_ie &&
+	    cfg->core_apn &&
+	    !parse_ctx->to_bss &&
+	    gbproxy_imsi_matches(cfg, GBPROX_MATCH_PATCHING, link_info) &&
+	    cfg->core_apn) {
+		size_t new_len;
+		gbproxy_patch_apn_ie(msg,
+				     parse_ctx->apn_ie, parse_ctx->apn_ie_len,
+				     peer, &new_len, parse_ctx->llc_msg_name);
+		*len_change += (int)new_len - (int)parse_ctx->apn_ie_len;
+
+		have_patched = 1;
+	}
+
+	if (have_patched) {
+		llc_len += *len_change;
+		ghp->crc_length += *len_change;
+
+		/* Fix FCS */
+		fcs = gprs_llc_fcs(llc, ghp->crc_length);
+		LOGP(DLLC, LOGL_DEBUG, "Updated LLC message, CRC: %06x -> %06x\n",
+		     ghp->fcs, fcs);
+
+		llc[llc_len - 3] = fcs & 0xff;
+		llc[llc_len - 2] = (fcs >> 8) & 0xff;
+		llc[llc_len - 1] = (fcs >> 16) & 0xff;
+	}
+
+	return have_patched;
+}
+
+/* patch BSSGP message to use core_plmn.mcc/mnc on the SGSN side */
+void gbproxy_patch_bssgp(struct msgb *msg, uint8_t *bssgp, size_t bssgp_len,
+			 struct gbproxy_peer *peer,
+			 struct gbproxy_link_info *link_info, int *len_change,
+			 struct gprs_gb_parse_context *parse_ctx)
+{
+	const char *err_info = NULL;
+	int err_ctr = -1;
+
+	if (parse_ctx->bssgp_raid_enc)
+		gbproxy_patch_raid((struct gsm48_ra_id *)parse_ctx->bssgp_raid_enc, peer,
+				   parse_ctx->to_bss, "BSSGP");
+
+	if (parse_ctx->need_decryption &&
+	    (peer->cfg->patch_ptmsi || peer->cfg->core_apn)) {
+		/* Patching LLC messages has been requested
+		 * explicitly, but the message (including the
+		 * type) is encrypted, so we possibly fail to
+		 * patch the LLC part of the message. */
+		err_ctr = GBPROX_PEER_CTR_PATCH_CRYPT_ERR;
+		err_info = "GMM message is encrypted";
+		goto patch_error;
+	}
+
+	if (!link_info && parse_ctx->tlli_enc && parse_ctx->to_bss) {
+		/* Happens with unknown (not cached) TLLI coming from
+		 * the SGSN */
+		/* TODO: What shall be done with the message in this case? */
+		err_ctr = GBPROX_PEER_CTR_TLLI_UNKNOWN;
+		err_info = "TLLI sent by the SGSN is unknown";
+		goto patch_error;
+	}
+
+	if (!link_info)
+		return;
+
+	if (parse_ctx->tlli_enc && peer->cfg->patch_ptmsi) {
+		uint32_t tlli = gbproxy_map_tlli(parse_ctx->tlli,
+						 link_info, parse_ctx->to_bss);
+
+		if (tlli) {
+			gbproxy_patch_tlli(parse_ctx->tlli_enc, peer, tlli,
+					   parse_ctx->to_bss, "TLLI");
+			parse_ctx->tlli = tlli;
+		} else {
+			/* Internal error */
+			err_ctr = GBPROX_PEER_CTR_PATCH_ERR;
+			err_info = "Replacement TLLI is 0";
+			goto patch_error;
+		}
+	}
+
+	if (parse_ctx->bssgp_ptmsi_enc && peer->cfg->patch_ptmsi) {
+		uint32_t ptmsi;
+		if (parse_ctx->to_bss)
+			ptmsi = link_info->tlli.ptmsi;
+		else
+			ptmsi = link_info->sgsn_tlli.ptmsi;
+
+		if (ptmsi != GSM_RESERVED_TMSI)
+			gbproxy_patch_ptmsi(
+				parse_ctx->bssgp_ptmsi_enc, peer,
+				ptmsi, parse_ctx->to_bss, "BSSGP P-TMSI");
+	}
+
+	if (parse_ctx->llc) {
+		uint8_t *llc = parse_ctx->llc;
+		size_t llc_len = parse_ctx->llc_len;
+		int llc_len_change = 0;
+
+		gbproxy_patch_llc(msg, llc, llc_len, peer, link_info,
+				  &llc_len_change, parse_ctx);
+		/* Note that the APN might have been resized here, but no
+		 * pointer int the parse_ctx will refer to an adress after the
+		 * APN. So it's possible to patch first and do the TLLI
+		 * handling afterwards. */
+
+		if (llc_len_change) {
+			llc_len += llc_len_change;
+
+			/* Fix LLC IE len */
+			/* TODO: This is a kludge, but the a pointer to the
+			 * start of the IE is not available here */
+			if (llc[-2] == BSSGP_IE_LLC_PDU && llc[-1] & 0x80) {
+				/* most probably a one byte length */
+				if (llc_len > 127) {
+					err_info = "Cannot increase size";
+					err_ctr = GBPROX_PEER_CTR_PATCH_ERR;
+					goto patch_error;
+				}
+				llc[-1] = llc_len | 0x80;
+			} else {
+				llc[-2] = (llc_len >> 8) & 0x7f;
+				llc[-1] = llc_len & 0xff;
+			}
+			*len_change += llc_len_change;
+		}
+		/* Note that the tp struct might contain invalid pointers here
+		 * if the LLC field has changed its size */
+		parse_ctx->llc_len = llc_len;
+	}
+	return;
+
+patch_error:
+	OSMO_ASSERT(err_ctr >= 0);
+	rate_ctr_inc(&peer->ctrg->ctr[err_ctr]);
+	LOGP(DGPRS, LOGL_ERROR,
+	     "NSEI=%u(%s) failed to patch BSSGP message as requested: %s.\n",
+	     msgb_nsei(msg), parse_ctx->to_bss ? "SGSN" : "BSS",
+	     err_info);
+}
+
+void gbproxy_clear_patch_filter(struct gbproxy_match *match)
+{
+	if (match->enable) {
+		regfree(&match->re_comp);
+		match->enable = false;
+	}
+	talloc_free(match->re_str);
+	match->re_str = NULL;
+}
+
+int gbproxy_set_patch_filter(struct gbproxy_match *match, const char *filter,
+		const char **err_msg)
+{
+	static char err_buf[300];
+	int rc;
+
+	gbproxy_clear_patch_filter(match);
+
+	if (!filter)
+		return 0;
+
+	rc = regcomp(&match->re_comp, filter,
+		     REG_EXTENDED | REG_NOSUB | REG_ICASE);
+
+	if (rc == 0) {
+		match->enable = true;
+		match->re_str = talloc_strdup(tall_sgsn_ctx, filter);
+		return 0;
+	}
+
+	if (err_msg) {
+		regerror(rc, &match->re_comp,
+			 err_buf, sizeof(err_buf));
+		*err_msg = err_buf;
+	}
+
+	return -1;
+}
+
+int gbproxy_check_imsi(struct gbproxy_match *match,
+		       const uint8_t *imsi, size_t imsi_len)
+{
+	char mi_buf[200];
+	int rc;
+
+	if (!match->enable)
+		return 1;
+
+	rc = gprs_is_mi_imsi(imsi, imsi_len);
+	if (rc > 0)
+		rc = gsm48_mi_to_string(mi_buf, sizeof(mi_buf), imsi, imsi_len);
+	if (rc <= 0) {
+		LOGP(DGPRS, LOGL_NOTICE, "Invalid IMSI %s\n",
+		     osmo_hexdump(imsi, imsi_len));
+		return -1;
+	}
+
+	LOGP(DGPRS, LOGL_DEBUG, "Checking IMSI '%s' (%d)\n", mi_buf, rc);
+
+	rc = regexec(&match->re_comp, mi_buf, 0, NULL, 0);
+	if (rc == REG_NOMATCH) {
+		LOGP(DGPRS, LOGL_INFO,
+		       "IMSI '%s' doesn't match pattern '%s'\n",
+		       mi_buf, match->re_str);
+		return 0;
+	}
+
+	return 1;
+}
diff --git a/src/gb_proxy_peer.c b/src/gb_proxy_peer.c
new file mode 100644
index 0000000..48482b6
--- /dev/null
+++ b/src/gb_proxy_peer.c
@@ -0,0 +1,240 @@
+/* Gb proxy peer handling */
+
+/* (C) 2010 by Harald Welte <laforge@gnumonks.org>
+ * (C) 2010-2013 by On-Waves
+ * (C) 2013 by Holger Hans Peter Freyther
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <osmocom/sgsn/gb_proxy.h>
+
+#include <osmocom/sgsn/debug.h>
+
+#include <osmocom/gprs/protocol/gsm_08_18.h>
+#include <osmocom/core/rate_ctr.h>
+#include <osmocom/core/stats.h>
+#include <osmocom/core/talloc.h>
+#include <osmocom/gsm/tlv.h>
+
+#include <string.h>
+
+extern void *tall_sgsn_ctx;
+
+static const struct rate_ctr_desc peer_ctr_description[] = {
+	{ "blocked",	   "BVC Block                       " },
+	{ "unblocked",	   "BVC Unblock                     " },
+	{ "dropped",	   "BVC blocked, dropped packet     " },
+	{ "inv-nsei",	   "NSEI mismatch                   " },
+	{ "tx-err",	   "NS Transmission error           " },
+	{ "raid-mod:bss",  "RAID patched              (BSS )" },
+	{ "raid-mod:sgsn", "RAID patched              (SGSN)" },
+	{ "apn-mod:sgsn",  "APN patched                     " },
+	{ "tlli-mod:bss",  "TLLI patched              (BSS )" },
+	{ "tlli-mod:sgsn", "TLLI patched              (SGSN)" },
+	{ "ptmsi-mod:bss", "P-TMSI patched            (BSS )" },
+	{ "ptmsi-mod:sgsn","P-TMSI patched            (SGSN)" },
+	{ "mod-crypt-err", "Patch error: encrypted          " },
+	{ "mod-err",	   "Patch error: other              " },
+	{ "attach-reqs",   "Attach Request count            " },
+	{ "attach-rejs",   "Attach Reject count             " },
+	{ "attach-acks",   "Attach Accept count             " },
+	{ "attach-cpls",   "Attach Completed count          " },
+	{ "ra-upd-reqs",   "RoutingArea Update Request count" },
+	{ "ra-upd-rejs",   "RoutingArea Update Reject count " },
+	{ "ra-upd-acks",   "RoutingArea Update Accept count " },
+	{ "ra-upd-cpls",   "RoutingArea Update Compltd count" },
+	{ "gmm-status",    "GMM Status count           (BSS)" },
+	{ "gmm-status",    "GMM Status count          (SGSN)" },
+	{ "detach-reqs",   "Detach Request count            " },
+	{ "detach-acks",   "Detach Accept count             " },
+	{ "pdp-act-reqs",  "PDP Activation Request count    " },
+	{ "pdp-act-rejs",  "PDP Activation Reject count     " },
+	{ "pdp-act-acks",  "PDP Activation Accept count     " },
+	{ "pdp-deact-reqs","PDP Deactivation Request count  " },
+	{ "pdp-deact-acks","PDP Deactivation Accept count   " },
+	{ "tlli-unknown",  "TLLI from SGSN unknown          " },
+	{ "tlli-cache",    "TLLI cache size                 " },
+};
+
+osmo_static_assert(ARRAY_SIZE(peer_ctr_description) == GBPROX_PEER_CTR_LAST, everything_described);
+
+static const struct rate_ctr_group_desc peer_ctrg_desc = {
+	.group_name_prefix = "gbproxy:peer",
+	.group_description = "GBProxy Peer Statistics",
+	.num_ctr = ARRAY_SIZE(peer_ctr_description),
+	.ctr_desc = peer_ctr_description,
+	.class_id = OSMO_STATS_CLASS_PEER,
+};
+
+
+/* Find the gbprox_peer by its BVCI */
+struct gbproxy_peer *gbproxy_peer_by_bvci(struct gbproxy_config *cfg, uint16_t bvci)
+{
+	struct gbproxy_peer *peer;
+	llist_for_each_entry(peer, &cfg->bts_peers, list) {
+		if (peer->bvci == bvci)
+			return peer;
+	}
+	return NULL;
+}
+
+/* Find the gbprox_peer by its NSEI */
+struct gbproxy_peer *gbproxy_peer_by_nsei(struct gbproxy_config *cfg,
+					  uint16_t nsei)
+{
+	struct gbproxy_peer *peer;
+	llist_for_each_entry(peer, &cfg->bts_peers, list) {
+		if (peer->nsei == nsei)
+			return peer;
+	}
+	return NULL;
+}
+
+/* look-up a peer by its Routeing Area Identification (RAI) */
+struct gbproxy_peer *gbproxy_peer_by_rai(struct gbproxy_config *cfg,
+					 const uint8_t *ra)
+{
+	struct gbproxy_peer *peer;
+	llist_for_each_entry(peer, &cfg->bts_peers, list) {
+		if (!memcmp(peer->ra, ra, 6))
+			return peer;
+	}
+	return NULL;
+}
+
+/* look-up a peer by its Location Area Identification (LAI) */
+struct gbproxy_peer *gbproxy_peer_by_lai(struct gbproxy_config *cfg,
+					 const uint8_t *la)
+{
+	struct gbproxy_peer *peer;
+	llist_for_each_entry(peer, &cfg->bts_peers, list) {
+		if (!memcmp(peer->ra, la, 5))
+			return peer;
+	}
+	return NULL;
+}
+
+/* look-up a peer by its Location Area Code (LAC) */
+struct gbproxy_peer *gbproxy_peer_by_lac(struct gbproxy_config *cfg,
+					 const uint8_t *la)
+{
+	struct gbproxy_peer *peer;
+	llist_for_each_entry(peer, &cfg->bts_peers, list) {
+		if (!memcmp(peer->ra + 3, la + 3, 2))
+			return peer;
+	}
+	return NULL;
+}
+
+struct gbproxy_peer *gbproxy_peer_by_bssgp_tlv(struct gbproxy_config *cfg,
+					       struct tlv_parsed *tp)
+{
+	if (TLVP_PRESENT(tp, BSSGP_IE_BVCI)) {
+		uint16_t bvci;
+
+		bvci = ntohs(tlvp_val16_unal(tp, BSSGP_IE_BVCI));
+		if (bvci >= 2)
+			return gbproxy_peer_by_bvci(cfg, bvci);
+	}
+
+	if (TLVP_PRESENT(tp, BSSGP_IE_ROUTEING_AREA)) {
+		uint8_t *rai = (uint8_t *)TLVP_VAL(tp, BSSGP_IE_ROUTEING_AREA);
+		/* Only compare LAC part, since MCC/MNC are possibly patched.
+		 * Since the LAC of different BSS must be different when
+		 * MCC/MNC are patched, collisions shouldn't happen. */
+		return gbproxy_peer_by_lac(cfg, rai);
+	}
+
+	if (TLVP_PRESENT(tp, BSSGP_IE_LOCATION_AREA)) {
+		uint8_t *lai = (uint8_t *)TLVP_VAL(tp, BSSGP_IE_LOCATION_AREA);
+		return gbproxy_peer_by_lac(cfg, lai);
+	}
+
+	return NULL;
+}
+
+static void clean_stale_timer_cb(void *data)
+{
+	time_t now;
+	struct timespec ts = {0,};
+	struct gbproxy_peer *peer = (struct gbproxy_peer *) data;
+
+	osmo_clock_gettime(CLOCK_MONOTONIC, &ts);
+	now = ts.tv_sec;
+	gbproxy_remove_stale_link_infos(peer, now);
+	if (peer->cfg->clean_stale_timer_freq != 0)
+		osmo_timer_schedule(&peer->clean_stale_timer,
+					peer->cfg->clean_stale_timer_freq, 0);
+}
+
+struct gbproxy_peer *gbproxy_peer_alloc(struct gbproxy_config *cfg, uint16_t bvci)
+{
+	struct gbproxy_peer *peer;
+
+	peer = talloc_zero(tall_sgsn_ctx, struct gbproxy_peer);
+	if (!peer)
+		return NULL;
+
+	peer->bvci = bvci;
+	peer->ctrg = rate_ctr_group_alloc(peer, &peer_ctrg_desc, bvci);
+	if (!peer->ctrg) {
+		talloc_free(peer);
+		return NULL;
+	}
+	peer->cfg = cfg;
+
+	llist_add(&peer->list, &cfg->bts_peers);
+
+	INIT_LLIST_HEAD(&peer->patch_state.logical_links);
+
+	osmo_timer_setup(&peer->clean_stale_timer, clean_stale_timer_cb, peer);
+	if (peer->cfg->clean_stale_timer_freq != 0)
+		osmo_timer_schedule(&peer->clean_stale_timer,
+					peer->cfg->clean_stale_timer_freq, 0);
+
+	return peer;
+}
+
+void gbproxy_peer_free(struct gbproxy_peer *peer)
+{
+	llist_del(&peer->list);
+	osmo_timer_del(&peer->clean_stale_timer);
+	gbproxy_delete_link_infos(peer);
+
+	rate_ctr_group_free(peer->ctrg);
+	peer->ctrg = NULL;
+
+	talloc_free(peer);
+}
+
+int gbproxy_cleanup_peers(struct gbproxy_config *cfg, uint16_t nsei, uint16_t bvci)
+{
+	int counter = 0;
+	struct gbproxy_peer *peer, *tmp;
+
+	llist_for_each_entry_safe(peer, tmp, &cfg->bts_peers, list) {
+		if (peer->nsei != nsei)
+			continue;
+		if (bvci && peer->bvci != bvci)
+			continue;
+
+		gbproxy_peer_free(peer);
+		counter += 1;
+	}
+
+	return counter;
+}
diff --git a/src/gb_proxy_tlli.c b/src/gb_proxy_tlli.c
new file mode 100644
index 0000000..4e21ede
--- /dev/null
+++ b/src/gb_proxy_tlli.c
@@ -0,0 +1,723 @@
+/* Gb-proxy TLLI state handling */
+
+/* (C) 2014 by On-Waves
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <osmocom/gsm/gsm48.h>
+
+#include <osmocom/sgsn/gb_proxy.h>
+
+#include <osmocom/sgsn/gprs_utils.h>
+#include <osmocom/sgsn/gprs_gb_parse.h>
+
+#include <osmocom/sgsn/debug.h>
+
+#include <osmocom/gsm/gsm_utils.h>
+
+#include <osmocom/core/rate_ctr.h>
+#include <osmocom/core/talloc.h>
+
+struct gbproxy_link_info *gbproxy_link_info_by_tlli(struct gbproxy_peer *peer,
+					    uint32_t tlli)
+{
+	struct gbproxy_link_info *link_info;
+	struct gbproxy_patch_state *state = &peer->patch_state;
+
+	if (!tlli)
+		return NULL;
+
+	llist_for_each_entry(link_info, &state->logical_links, list)
+		if (link_info->tlli.current == tlli ||
+		    link_info->tlli.assigned == tlli)
+			return link_info;
+
+	return NULL;
+}
+
+struct gbproxy_link_info *gbproxy_link_info_by_ptmsi(
+	struct gbproxy_peer *peer,
+	uint32_t ptmsi)
+{
+	struct gbproxy_link_info *link_info;
+	struct gbproxy_patch_state *state = &peer->patch_state;
+
+	if (ptmsi == GSM_RESERVED_TMSI)
+		return NULL;
+
+	llist_for_each_entry(link_info, &state->logical_links, list)
+		if (link_info->tlli.ptmsi == ptmsi)
+			return link_info;
+
+	return NULL;
+}
+
+struct gbproxy_link_info *gbproxy_link_info_by_any_sgsn_tlli(
+	struct gbproxy_peer *peer,
+	uint32_t tlli)
+{
+	struct gbproxy_link_info *link_info;
+	struct gbproxy_patch_state *state = &peer->patch_state;
+
+	if (!tlli)
+		return NULL;
+
+	/* Don't care about the NSEI */
+	llist_for_each_entry(link_info, &state->logical_links, list)
+		if (link_info->sgsn_tlli.current == tlli ||
+		     link_info->sgsn_tlli.assigned == tlli)
+			return link_info;
+
+	return NULL;
+}
+
+struct gbproxy_link_info *gbproxy_link_info_by_sgsn_tlli(
+	struct gbproxy_peer *peer,
+	uint32_t tlli, uint32_t sgsn_nsei)
+{
+	struct gbproxy_link_info *link_info;
+	struct gbproxy_patch_state *state = &peer->patch_state;
+
+	if (!tlli)
+		return NULL;
+
+	llist_for_each_entry(link_info, &state->logical_links, list)
+		if ((link_info->sgsn_tlli.current == tlli ||
+		     link_info->sgsn_tlli.assigned == tlli) &&
+		    link_info->sgsn_nsei == sgsn_nsei)
+			return link_info;
+
+	return NULL;
+}
+
+struct gbproxy_link_info *gbproxy_link_info_by_imsi(
+	struct gbproxy_peer *peer,
+	const uint8_t *imsi,
+	size_t imsi_len)
+{
+	struct gbproxy_link_info *link_info;
+	struct gbproxy_patch_state *state = &peer->patch_state;
+
+	if (!gprs_is_mi_imsi(imsi, imsi_len))
+		return NULL;
+
+	llist_for_each_entry(link_info, &state->logical_links, list) {
+		if (link_info->imsi_len != imsi_len)
+			continue;
+		if (memcmp(link_info->imsi, imsi, imsi_len) != 0)
+			continue;
+
+		return link_info;
+	}
+
+	return NULL;
+}
+
+void gbproxy_link_info_discard_messages(struct gbproxy_link_info *link_info)
+{
+	struct msgb *msg, *nxt;
+
+	llist_for_each_entry_safe(msg, nxt, &link_info->stored_msgs, list) {
+		llist_del(&msg->list);
+		msgb_free(msg);
+	}
+}
+
+void gbproxy_delete_link_info(struct gbproxy_peer *peer,
+			 struct gbproxy_link_info *link_info)
+{
+	struct gbproxy_patch_state *state = &peer->patch_state;
+
+	gbproxy_link_info_discard_messages(link_info);
+
+	llist_del(&link_info->list);
+	talloc_free(link_info);
+	state->logical_link_count -= 1;
+
+	peer->ctrg->ctr[GBPROX_PEER_CTR_TLLI_CACHE_SIZE].current =
+		state->logical_link_count;
+}
+
+void gbproxy_delete_link_infos(struct gbproxy_peer *peer)
+{
+	struct gbproxy_link_info *link_info, *nxt;
+	struct gbproxy_patch_state *state = &peer->patch_state;
+
+	llist_for_each_entry_safe(link_info, nxt, &state->logical_links, list)
+		gbproxy_delete_link_info(peer, link_info);
+
+	OSMO_ASSERT(state->logical_link_count == 0);
+	OSMO_ASSERT(llist_empty(&state->logical_links));
+}
+
+void gbproxy_attach_link_info(struct gbproxy_peer *peer, time_t now,
+			      struct gbproxy_link_info *link_info)
+{
+	struct gbproxy_patch_state *state = &peer->patch_state;
+
+	link_info->timestamp = now;
+	llist_add(&link_info->list, &state->logical_links);
+	state->logical_link_count += 1;
+
+	peer->ctrg->ctr[GBPROX_PEER_CTR_TLLI_CACHE_SIZE].current =
+		state->logical_link_count;
+}
+
+int gbproxy_remove_stale_link_infos(struct gbproxy_peer *peer, time_t now)
+{
+	struct gbproxy_patch_state *state = &peer->patch_state;
+	int exceeded_max_len = 0;
+	int deleted_count = 0;
+	int check_for_age;
+
+	if (peer->cfg->tlli_max_len > 0)
+		exceeded_max_len =
+			state->logical_link_count - peer->cfg->tlli_max_len;
+
+	check_for_age = peer->cfg->tlli_max_age > 0;
+
+	for (; exceeded_max_len > 0; exceeded_max_len--) {
+		struct gbproxy_link_info *link_info;
+		OSMO_ASSERT(!llist_empty(&state->logical_links));
+		link_info = llist_entry(state->logical_links.prev,
+					struct gbproxy_link_info,
+					list);
+		LOGP(DGPRS, LOGL_INFO,
+		     "Removing TLLI %08x from list "
+		     "(stale, length %d, max_len exceeded)\n",
+		     link_info->tlli.current, state->logical_link_count);
+
+		gbproxy_delete_link_info(peer, link_info);
+		deleted_count += 1;
+	}
+
+	while (check_for_age && !llist_empty(&state->logical_links)) {
+		time_t age;
+		struct gbproxy_link_info *link_info;
+		link_info = llist_entry(state->logical_links.prev,
+					struct gbproxy_link_info,
+					list);
+		age = now - link_info->timestamp;
+		/* age < 0 only happens after system time jumps, discard entry */
+		if (age <= peer->cfg->tlli_max_age && age >= 0) {
+			check_for_age = 0;
+			continue;
+		}
+
+		LOGP(DGPRS, LOGL_INFO,
+		     "Removing TLLI %08x from list "
+		     "(stale, age %d, max_age exceeded)\n",
+		     link_info->tlli.current, (int)age);
+
+		gbproxy_delete_link_info(peer, link_info);
+		deleted_count += 1;
+	}
+
+	return deleted_count;
+}
+
+struct gbproxy_link_info *gbproxy_link_info_alloc( struct gbproxy_peer *peer)
+{
+	struct gbproxy_link_info *link_info;
+
+	link_info = talloc_zero(peer, struct gbproxy_link_info);
+	link_info->tlli.ptmsi = GSM_RESERVED_TMSI;
+	link_info->sgsn_tlli.ptmsi = GSM_RESERVED_TMSI;
+
+	link_info->vu_gen_tx_bss = GBPROXY_INIT_VU_GEN_TX;
+
+	INIT_LLIST_HEAD(&link_info->stored_msgs);
+
+	return link_info;
+}
+
+void gbproxy_detach_link_info(
+	struct gbproxy_peer *peer,
+	struct gbproxy_link_info *link_info)
+{
+	struct gbproxy_patch_state *state = &peer->patch_state;
+
+	llist_del(&link_info->list);
+	OSMO_ASSERT(state->logical_link_count > 0);
+	state->logical_link_count -= 1;
+
+	peer->ctrg->ctr[GBPROX_PEER_CTR_TLLI_CACHE_SIZE].current =
+		state->logical_link_count;
+}
+
+void gbproxy_update_link_info(struct gbproxy_link_info *link_info,
+			      const uint8_t *imsi, size_t imsi_len)
+{
+	if (!gprs_is_mi_imsi(imsi, imsi_len))
+		return;
+
+	link_info->imsi_len = imsi_len;
+	link_info->imsi =
+		talloc_realloc_size(link_info, link_info->imsi, imsi_len);
+	OSMO_ASSERT(link_info->imsi != NULL);
+	memcpy(link_info->imsi, imsi, imsi_len);
+}
+
+void gbproxy_reassign_tlli(struct gbproxy_tlli_state *tlli_state,
+			   struct gbproxy_peer *peer, uint32_t new_tlli)
+{
+	if (new_tlli == tlli_state->current)
+		return;
+
+	LOGP(DGPRS, LOGL_INFO,
+	     "The TLLI has been reassigned from %08x to %08x\n",
+	     tlli_state->current, new_tlli);
+
+	/* Remember assigned TLLI */
+	tlli_state->assigned = new_tlli;
+	tlli_state->bss_validated = false;
+	tlli_state->net_validated = false;
+}
+
+uint32_t gbproxy_map_tlli(uint32_t other_tlli,
+			  struct gbproxy_link_info *link_info, int to_bss)
+{
+	uint32_t tlli = 0;
+	struct gbproxy_tlli_state *src, *dst;
+	if (to_bss) {
+		src = &link_info->sgsn_tlli;
+		dst = &link_info->tlli;
+	} else {
+		src = &link_info->tlli;
+		dst = &link_info->sgsn_tlli;
+	}
+	if (src->current == other_tlli)
+		tlli = dst->current;
+	else if (src->assigned == other_tlli)
+		tlli = dst->assigned;
+
+	return tlli;
+}
+
+static void gbproxy_validate_tlli(struct gbproxy_tlli_state *tlli_state,
+				  uint32_t tlli, int to_bss)
+{
+	LOGP(DGPRS, LOGL_DEBUG,
+	     "%s({current = %08x, assigned = %08x, net_vld = %d, bss_vld = %d}, %08x)\n",
+	     __func__, tlli_state->current, tlli_state->assigned,
+	     tlli_state->net_validated, tlli_state->bss_validated, tlli);
+
+	if (!tlli_state->assigned || tlli_state->assigned != tlli)
+		return;
+
+	/* TODO: Is this ok? Check spec */
+	if (gprs_tlli_type(tlli) != TLLI_LOCAL)
+		return;
+
+	/* See GSM 04.08, 4.7.1.5 */
+	if (to_bss)
+		tlli_state->net_validated = true;
+	else
+		tlli_state->bss_validated = true;
+
+	if (!tlli_state->bss_validated || !tlli_state->net_validated)
+		return;
+
+	LOGP(DGPRS, LOGL_INFO,
+	     "The TLLI %08x has been validated (was %08x)\n",
+	     tlli_state->assigned, tlli_state->current);
+
+	tlli_state->current = tlli;
+	tlli_state->assigned = 0;
+}
+
+static void gbproxy_touch_link_info(struct gbproxy_peer *peer,
+				    struct gbproxy_link_info *link_info,
+				    time_t now)
+{
+	gbproxy_detach_link_info(peer, link_info);
+	gbproxy_attach_link_info(peer, now, link_info);
+}
+
+static int gbproxy_unregister_link_info(struct gbproxy_peer *peer,
+					 struct gbproxy_link_info *link_info)
+{
+	if (!link_info)
+		return 1;
+
+	if (link_info->tlli.ptmsi == GSM_RESERVED_TMSI && !link_info->imsi_len) {
+		LOGP(DGPRS, LOGL_INFO,
+		     "Removing TLLI %08x from list (P-TMSI or IMSI are not set)\n",
+		     link_info->tlli.current);
+		gbproxy_delete_link_info(peer, link_info);
+		return 1;
+	}
+
+	link_info->tlli.current = 0;
+	link_info->tlli.assigned = 0;
+	link_info->sgsn_tlli.current = 0;
+	link_info->sgsn_tlli.assigned = 0;
+
+	link_info->is_deregistered = true;
+
+	gbproxy_reset_link(link_info);
+
+	return 0;
+}
+
+int gbproxy_imsi_matches(struct gbproxy_config *cfg,
+			 enum gbproxy_match_id match_id,
+			 struct gbproxy_link_info *link_info)
+{
+	struct gbproxy_match *match;
+	OSMO_ASSERT(match_id >= 0 && match_id < ARRAY_SIZE(cfg->matches));
+
+	match = &cfg->matches[match_id];
+	if (!match->enable)
+		return 1;
+
+	return link_info != NULL && link_info->is_matching[match_id];
+}
+
+static void gbproxy_assign_imsi(struct gbproxy_peer *peer,
+			 struct gbproxy_link_info *link_info,
+			 struct gprs_gb_parse_context *parse_ctx)
+{
+	int imsi_matches;
+	struct gbproxy_link_info *other_link_info;
+	enum gbproxy_match_id match_id;
+
+	/* Make sure that there is a second entry with the same IMSI */
+	other_link_info = gbproxy_link_info_by_imsi(
+		peer, parse_ctx->imsi, parse_ctx->imsi_len);
+
+	if (other_link_info && other_link_info != link_info) {
+		char mi_buf[200];
+		mi_buf[0] = '\0';
+		gsm48_mi_to_string(mi_buf, sizeof(mi_buf),
+				   parse_ctx->imsi, parse_ctx->imsi_len);
+		LOGP(DGPRS, LOGL_INFO,
+		     "Removing TLLI %08x from list (IMSI %s re-used)\n",
+		     other_link_info->tlli.current, mi_buf);
+		gbproxy_delete_link_info(peer, other_link_info);
+	}
+
+	/* Update the IMSI field */
+	gbproxy_update_link_info(link_info,
+				 parse_ctx->imsi, parse_ctx->imsi_len);
+
+	/* Check, whether the IMSI matches */
+	OSMO_ASSERT(ARRAY_SIZE(link_info->is_matching) ==
+		    ARRAY_SIZE(peer->cfg->matches));
+	for (match_id = 0; match_id < ARRAY_SIZE(link_info->is_matching);
+	     ++match_id) {
+		imsi_matches = gbproxy_check_imsi(
+			&peer->cfg->matches[match_id],
+			parse_ctx->imsi, parse_ctx->imsi_len);
+		if (imsi_matches >= 0)
+			link_info->is_matching[match_id] = imsi_matches ? true : false;
+	}
+}
+
+static int gbproxy_tlli_match(const struct gbproxy_tlli_state *a,
+			      const struct gbproxy_tlli_state *b)
+{
+	if (a->current && a->current == b->current)
+		return 1;
+
+	if (a->assigned && a->assigned == b->assigned)
+		return 1;
+
+	if (a->ptmsi != GSM_RESERVED_TMSI && a->ptmsi == b->ptmsi)
+		return 1;
+
+	return 0;
+}
+
+static void gbproxy_remove_matching_link_infos(
+	struct gbproxy_peer *peer, struct gbproxy_link_info *link_info)
+{
+	struct gbproxy_link_info *info, *nxt;
+	struct gbproxy_patch_state *state = &peer->patch_state;
+
+	/* Make sure that there is no second entry with the same P-TMSI or TLLI */
+	llist_for_each_entry_safe(info, nxt, &state->logical_links, list) {
+		if (info == link_info)
+			continue;
+
+		if (!gbproxy_tlli_match(&link_info->tlli, &info->tlli) &&
+		    (link_info->sgsn_nsei != info->sgsn_nsei ||
+		     !gbproxy_tlli_match(&link_info->sgsn_tlli, &info->sgsn_tlli)))
+			continue;
+
+		LOGP(DGPRS, LOGL_INFO,
+		     "Removing TLLI %08x from list (P-TMSI/TLLI re-used)\n",
+		     info->tlli.current);
+		gbproxy_delete_link_info(peer, info);
+	}
+}
+
+static struct gbproxy_link_info *gbproxy_get_link_info_ul(
+	struct gbproxy_peer *peer,
+	int *tlli_is_valid,
+	struct gprs_gb_parse_context *parse_ctx)
+{
+	struct gbproxy_link_info *link_info = NULL;
+
+	if (parse_ctx->tlli_enc) {
+		link_info = gbproxy_link_info_by_tlli(peer, parse_ctx->tlli);
+
+		if (link_info) {
+			*tlli_is_valid = 1;
+			return link_info;
+		}
+	}
+
+	*tlli_is_valid = 0;
+
+	if (!link_info && parse_ctx->imsi) {
+		link_info = gbproxy_link_info_by_imsi(
+			peer, parse_ctx->imsi, parse_ctx->imsi_len);
+	}
+
+	if (!link_info && parse_ctx->ptmsi_enc && !parse_ctx->old_raid_is_foreign) {
+		uint32_t bss_ptmsi;
+		gprs_parse_tmsi(parse_ctx->ptmsi_enc, &bss_ptmsi);
+		link_info = gbproxy_link_info_by_ptmsi(peer, bss_ptmsi);
+	}
+
+	if (!link_info)
+		return NULL;
+
+	link_info->is_deregistered = false;
+
+	return link_info;
+}
+
+struct gbproxy_link_info *gbproxy_update_link_state_ul(
+	struct gbproxy_peer *peer,
+	time_t now,
+	struct gprs_gb_parse_context *parse_ctx)
+{
+	struct gbproxy_link_info *link_info;
+	int tlli_is_valid;
+
+	link_info = gbproxy_get_link_info_ul(peer, &tlli_is_valid, parse_ctx);
+
+	if (parse_ctx->tlli_enc && parse_ctx->llc) {
+		uint32_t sgsn_tlli;
+
+		if (!link_info) {
+			LOGP(DGPRS, LOGL_INFO, "Adding TLLI %08x to list\n",
+			    parse_ctx->tlli);
+			link_info = gbproxy_link_info_alloc(peer);
+			gbproxy_attach_link_info(peer, now, link_info);
+
+			/* Setup TLLIs */
+			sgsn_tlli = gbproxy_make_sgsn_tlli(peer, link_info,
+							   parse_ctx->tlli);
+			link_info->sgsn_tlli.current = sgsn_tlli;
+			link_info->tlli.current = parse_ctx->tlli;
+		} else if (!tlli_is_valid) {
+			/* New TLLI (info found by IMSI or P-TMSI) */
+			link_info->tlli.current = parse_ctx->tlli;
+			link_info->tlli.assigned = 0;
+			link_info->sgsn_tlli.current =
+				gbproxy_make_sgsn_tlli(peer, link_info,
+						       parse_ctx->tlli);
+			link_info->sgsn_tlli.assigned = 0;
+			gbproxy_touch_link_info(peer, link_info, now);
+		} else {
+			sgsn_tlli = gbproxy_map_tlli(parse_ctx->tlli, link_info, 0);
+			if (!sgsn_tlli)
+				sgsn_tlli = gbproxy_make_sgsn_tlli(peer, link_info,
+								   parse_ctx->tlli);
+
+			gbproxy_validate_tlli(&link_info->tlli,
+					      parse_ctx->tlli, 0);
+			gbproxy_validate_tlli(&link_info->sgsn_tlli,
+					      sgsn_tlli, 0);
+			gbproxy_touch_link_info(peer, link_info, now);
+		}
+	} else if (link_info) {
+		gbproxy_touch_link_info(peer, link_info, now);
+	}
+
+	if (parse_ctx->imsi && link_info && link_info->imsi_len == 0)
+		gbproxy_assign_imsi(peer, link_info, parse_ctx);
+
+	return link_info;
+}
+
+static struct gbproxy_link_info *gbproxy_get_link_info_dl(
+	struct gbproxy_peer *peer,
+	struct gprs_gb_parse_context *parse_ctx)
+{
+	struct gbproxy_link_info *link_info = NULL;
+
+	/* Which key to use depends on its availability only, if that fails, do
+	 * not retry it with another key (e.g. IMSI). */
+	if (parse_ctx->tlli_enc)
+		link_info = gbproxy_link_info_by_sgsn_tlli(peer, parse_ctx->tlli,
+							   parse_ctx->peer_nsei);
+
+	/* TODO: Get link_info by (SGSN) P-TMSI if that is available (see
+	 * GSM 08.18, 7.2) instead of using the IMSI as key. */
+	else if (parse_ctx->imsi)
+		link_info = gbproxy_link_info_by_imsi(
+			peer, parse_ctx->imsi, parse_ctx->imsi_len);
+
+	if (link_info)
+		link_info->is_deregistered = false;
+
+	return link_info;
+}
+
+struct gbproxy_link_info *gbproxy_update_link_state_dl(
+	struct gbproxy_peer *peer,
+	time_t now,
+	struct gprs_gb_parse_context *parse_ctx)
+{
+	struct gbproxy_link_info *link_info = NULL;
+
+	link_info = gbproxy_get_link_info_dl(peer, parse_ctx);
+
+	if (parse_ctx->tlli_enc && parse_ctx->new_ptmsi_enc && link_info) {
+		/* A new P-TMSI has been signalled in the message,
+		 * register new TLLI */
+		uint32_t new_sgsn_ptmsi;
+		uint32_t new_bss_ptmsi = GSM_RESERVED_TMSI;
+		gprs_parse_tmsi(parse_ctx->new_ptmsi_enc, &new_sgsn_ptmsi);
+
+		if (link_info->sgsn_tlli.ptmsi == new_sgsn_ptmsi)
+			new_bss_ptmsi = link_info->tlli.ptmsi;
+
+		if (new_bss_ptmsi == GSM_RESERVED_TMSI)
+			new_bss_ptmsi = gbproxy_make_bss_ptmsi(peer, new_sgsn_ptmsi);
+
+		LOGP(DGPRS, LOGL_INFO,
+		     "Got new PTMSI %08x from SGSN, using %08x for BSS\n",
+		     new_sgsn_ptmsi, new_bss_ptmsi);
+		/* Setup PTMSIs */
+		link_info->sgsn_tlli.ptmsi = new_sgsn_ptmsi;
+		link_info->tlli.ptmsi = new_bss_ptmsi;
+	} else if (parse_ctx->tlli_enc && parse_ctx->new_ptmsi_enc && !link_info &&
+		   !peer->cfg->patch_ptmsi) {
+		/* A new P-TMSI has been signalled in the message with an unknown
+		 * TLLI, create a new link_info */
+		/* TODO: Add a test case for this branch */
+		uint32_t new_ptmsi;
+		gprs_parse_tmsi(parse_ctx->new_ptmsi_enc, &new_ptmsi);
+
+		LOGP(DGPRS, LOGL_INFO,
+		     "Adding TLLI %08x to list (SGSN, new P-TMSI is %08x)\n",
+		     parse_ctx->tlli, new_ptmsi);
+
+		link_info = gbproxy_link_info_alloc(peer);
+		link_info->sgsn_tlli.current = parse_ctx->tlli;
+		link_info->tlli.current = parse_ctx->tlli;
+		link_info->sgsn_tlli.ptmsi = new_ptmsi;
+		link_info->tlli.ptmsi = new_ptmsi;
+		gbproxy_attach_link_info(peer, now, link_info);
+	} else if (parse_ctx->tlli_enc && parse_ctx->llc && !link_info &&
+		   !peer->cfg->patch_ptmsi) {
+		/* Unknown SGSN TLLI, create a new link_info */
+		uint32_t new_ptmsi;
+		link_info = gbproxy_link_info_alloc(peer);
+		LOGP(DGPRS, LOGL_INFO, "Adding TLLI %08x to list (SGSN)\n",
+		     parse_ctx->tlli);
+
+		gbproxy_attach_link_info(peer, now, link_info);
+
+		/* Setup TLLIs */
+		link_info->sgsn_tlli.current = parse_ctx->tlli;
+		link_info->tlli.current = parse_ctx->tlli;
+
+		if (!parse_ctx->new_ptmsi_enc)
+			return link_info;
+		/* A new P-TMSI has been signalled in the message */
+
+		gprs_parse_tmsi(parse_ctx->new_ptmsi_enc, &new_ptmsi);
+		LOGP(DGPRS, LOGL_INFO,
+		     "Assigning new P-TMSI %08x\n", new_ptmsi);
+		/* Setup P-TMSIs */
+		link_info->sgsn_tlli.ptmsi = new_ptmsi;
+		link_info->tlli.ptmsi = new_ptmsi;
+	} else if (parse_ctx->tlli_enc && parse_ctx->llc && link_info) {
+		uint32_t bss_tlli = gbproxy_map_tlli(parse_ctx->tlli,
+						     link_info, 1);
+		gbproxy_validate_tlli(&link_info->sgsn_tlli, parse_ctx->tlli, 1);
+		gbproxy_validate_tlli(&link_info->tlli, bss_tlli, 1);
+		gbproxy_touch_link_info(peer, link_info, now);
+	} else if (link_info) {
+		gbproxy_touch_link_info(peer, link_info, now);
+	}
+
+	if (parse_ctx->imsi && link_info && link_info->imsi_len == 0)
+		gbproxy_assign_imsi(peer, link_info, parse_ctx);
+
+	return link_info;
+}
+
+int gbproxy_update_link_state_after(
+	struct gbproxy_peer *peer,
+	struct gbproxy_link_info *link_info,
+	time_t now,
+	struct gprs_gb_parse_context *parse_ctx)
+{
+	int rc = 0;
+	if (parse_ctx->invalidate_tlli && link_info) {
+		int keep_info =
+			peer->cfg->keep_link_infos == GBPROX_KEEP_ALWAYS ||
+			(peer->cfg->keep_link_infos == GBPROX_KEEP_REATTACH &&
+			 parse_ctx->await_reattach) ||
+			(peer->cfg->keep_link_infos == GBPROX_KEEP_IDENTIFIED &&
+			 link_info->imsi_len > 0);
+		if (keep_info) {
+			LOGP(DGPRS, LOGL_INFO, "Unregistering TLLI %08x\n",
+			     link_info->tlli.current);
+			rc = gbproxy_unregister_link_info(peer, link_info);
+		} else {
+			LOGP(DGPRS, LOGL_INFO, "Removing TLLI %08x from list\n",
+			     link_info->tlli.current);
+			gbproxy_delete_link_info(peer, link_info);
+			rc = 1;
+		}
+	} else if (parse_ctx->to_bss && parse_ctx->tlli_enc &&
+		   parse_ctx->new_ptmsi_enc && link_info) {
+		/* A new PTMSI has been signaled in the message,
+		 * register new TLLI */
+		uint32_t new_sgsn_ptmsi = link_info->sgsn_tlli.ptmsi;
+		uint32_t new_bss_ptmsi = link_info->tlli.ptmsi;
+		uint32_t new_sgsn_tlli;
+		uint32_t new_bss_tlli = 0;
+
+		new_sgsn_tlli = gprs_tmsi2tlli(new_sgsn_ptmsi, TLLI_LOCAL);
+		if (new_bss_ptmsi != GSM_RESERVED_TMSI)
+			new_bss_tlli = gprs_tmsi2tlli(new_bss_ptmsi, TLLI_LOCAL);
+		LOGP(DGPRS, LOGL_INFO,
+		     "Assigning new TLLI %08x to SGSN, %08x to BSS\n",
+		     new_sgsn_tlli, new_bss_tlli);
+
+		gbproxy_reassign_tlli(&link_info->sgsn_tlli,
+				      peer, new_sgsn_tlli);
+		gbproxy_reassign_tlli(&link_info->tlli,
+				      peer, new_bss_tlli);
+		gbproxy_remove_matching_link_infos(peer, link_info);
+	}
+
+	gbproxy_remove_stale_link_infos(peer, now);
+
+	return rc;
+}
+
+
diff --git a/src/gb_proxy_vty.c b/src/gb_proxy_vty.c
new file mode 100644
index 0000000..5c4f454
--- /dev/null
+++ b/src/gb_proxy_vty.c
@@ -0,0 +1,926 @@
+/*
+ * (C) 2010 by Harald Welte <laforge@gnumonks.org>
+ * (C) 2010 by On-Waves
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <string.h>
+#include <time.h>
+#include <inttypes.h>
+
+#include <osmocom/core/talloc.h>
+#include <osmocom/core/rate_ctr.h>
+#include <osmocom/gsm/gsm48.h>
+
+#include <osmocom/gprs/gprs_ns.h>
+#include <osmocom/gsm/apn.h>
+
+#include <osmocom/sgsn/debug.h>
+#include <osmocom/sgsn/gb_proxy.h>
+#include <osmocom/sgsn/gprs_utils.h>
+#include <osmocom/sgsn/vty.h>
+
+#include <osmocom/vty/command.h>
+#include <osmocom/vty/vty.h>
+#include <osmocom/vty/misc.h>
+
+static struct gbproxy_config *g_cfg = NULL;
+
+/*
+ * vty code for gbproxy below
+ */
+static struct cmd_node gbproxy_node = {
+	GBPROXY_NODE,
+	"%s(config-gbproxy)# ",
+	1,
+};
+
+static const struct value_string keep_modes[] = {
+	{GBPROX_KEEP_NEVER, "never"},
+	{GBPROX_KEEP_REATTACH, "re-attach"},
+	{GBPROX_KEEP_IDENTIFIED, "identified"},
+	{GBPROX_KEEP_ALWAYS, "always"},
+	{0, NULL}
+};
+
+static const struct value_string match_ids[] = {
+	{GBPROX_MATCH_PATCHING, "patching"},
+	{GBPROX_MATCH_ROUTING, "routing"},
+	{0, NULL}
+};
+
+static void gbprox_vty_print_peer(struct vty *vty, struct gbproxy_peer *peer)
+{
+	struct gprs_ra_id raid;
+	gsm48_parse_ra(&raid, peer->ra);
+
+	vty_out(vty, "NSEI %5u, PTP-BVCI %5u, "
+		"RAI %s", peer->nsei, peer->bvci, osmo_rai_name(&raid));
+	if (peer->blocked)
+		vty_out(vty, " [BVC-BLOCKED]");
+
+	vty_out(vty, "%s", VTY_NEWLINE);
+}
+
+static int config_write_gbproxy(struct vty *vty)
+{
+	enum gbproxy_match_id match_id;
+
+	vty_out(vty, "gbproxy%s", VTY_NEWLINE);
+
+	vty_out(vty, " sgsn nsei %u%s", g_cfg->nsip_sgsn_nsei,
+		VTY_NEWLINE);
+
+	if (g_cfg->core_plmn.mcc > 0)
+		vty_out(vty, " core-mobile-country-code %s%s",
+			osmo_mcc_name(g_cfg->core_plmn.mcc), VTY_NEWLINE);
+	if (g_cfg->core_plmn.mnc > 0)
+		vty_out(vty, " core-mobile-network-code %s%s",
+			osmo_mnc_name(g_cfg->core_plmn.mnc, g_cfg->core_plmn.mnc_3_digits), VTY_NEWLINE);
+
+	for (match_id = 0; match_id < ARRAY_SIZE(g_cfg->matches); ++match_id) {
+		struct gbproxy_match *match = &g_cfg->matches[match_id];
+		if (match->re_str)
+			vty_out(vty, " match-imsi %s %s%s",
+				get_value_string(match_ids, match_id),
+				match->re_str, VTY_NEWLINE);
+	}
+
+	if (g_cfg->core_apn != NULL) {
+	       if (g_cfg->core_apn_size > 0) {
+		       char str[500] = {0};
+		       vty_out(vty, " core-access-point-name %s%s",
+			       osmo_apn_to_str(str, g_cfg->core_apn,
+						 g_cfg->core_apn_size),
+			       VTY_NEWLINE);
+	       } else {
+		       vty_out(vty, " core-access-point-name none%s",
+			       VTY_NEWLINE);
+	       }
+	}
+
+	if (g_cfg->route_to_sgsn2)
+		vty_out(vty, " secondary-sgsn nsei %u%s", g_cfg->nsip_sgsn2_nsei,
+			VTY_NEWLINE);
+
+	if (g_cfg->clean_stale_timer_freq > 0)
+		vty_out(vty, " link-list clean-stale-timer %u%s",
+			g_cfg->clean_stale_timer_freq, VTY_NEWLINE);
+	if (g_cfg->tlli_max_age > 0)
+		vty_out(vty, " link-list max-age %d%s",
+			g_cfg->tlli_max_age, VTY_NEWLINE);
+	if (g_cfg->tlli_max_len > 0)
+		vty_out(vty, " link-list max-length %d%s",
+			g_cfg->tlli_max_len, VTY_NEWLINE);
+	vty_out(vty, " link-list keep-mode %s%s",
+		get_value_string(keep_modes, g_cfg->keep_link_infos),
+		VTY_NEWLINE);
+	if (g_cfg->stored_msgs_max_len > 0)
+		vty_out(vty, " link stored-msgs-max-length %"PRIu32"%s",
+			g_cfg->stored_msgs_max_len, VTY_NEWLINE);
+
+
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_gbproxy,
+      cfg_gbproxy_cmd,
+      "gbproxy",
+      "Configure the Gb proxy")
+{
+	vty->node = GBPROXY_NODE;
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_nsip_sgsn_nsei,
+      cfg_nsip_sgsn_nsei_cmd,
+      "sgsn nsei <0-65534>",
+      "SGSN information\n"
+      "NSEI to be used in the connection with the SGSN\n"
+      "The NSEI\n")
+{
+	unsigned int nsei = atoi(argv[0]);
+
+	if (g_cfg->route_to_sgsn2 && g_cfg->nsip_sgsn2_nsei == nsei) {
+		vty_out(vty, "SGSN NSEI %d conflicts with secondary SGSN NSEI%s",
+			nsei, VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
+	g_cfg->nsip_sgsn_nsei = nsei;
+	return CMD_SUCCESS;
+}
+
+#define GBPROXY_CORE_MNC_STR "Use this network code for the core network\n"
+
+DEFUN(cfg_gbproxy_core_mnc,
+      cfg_gbproxy_core_mnc_cmd,
+      "core-mobile-network-code <1-999>",
+      GBPROXY_CORE_MNC_STR "NCC value\n")
+{
+	uint16_t mnc;
+	bool mnc_3_digits;
+	if (osmo_mnc_from_str(argv[0], &mnc, &mnc_3_digits)) {
+		vty_out(vty, "%% Invalid MNC: %s%s", argv[0], VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+	g_cfg->core_plmn.mnc = mnc;
+	g_cfg->core_plmn.mnc_3_digits = mnc_3_digits;
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_gbproxy_no_core_mnc,
+      cfg_gbproxy_no_core_mnc_cmd,
+      "no core-mobile-network-code",
+      NO_STR GBPROXY_CORE_MNC_STR)
+{
+	g_cfg->core_plmn.mnc = 0;
+	g_cfg->core_plmn.mnc_3_digits = false;
+	return CMD_SUCCESS;
+}
+
+#define GBPROXY_CORE_MCC_STR "Use this country code for the core network\n"
+
+DEFUN(cfg_gbproxy_core_mcc,
+      cfg_gbproxy_core_mcc_cmd,
+      "core-mobile-country-code <1-999>",
+      GBPROXY_CORE_MCC_STR "MCC value\n")
+{
+	g_cfg->core_plmn.mcc = atoi(argv[0]);
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_gbproxy_no_core_mcc,
+      cfg_gbproxy_no_core_mcc_cmd,
+      "no core-mobile-country-code",
+      NO_STR GBPROXY_CORE_MCC_STR)
+{
+	g_cfg->core_plmn.mcc = 0;
+	return CMD_SUCCESS;
+}
+
+#define GBPROXY_MATCH_IMSI_STR "Restrict actions to certain IMSIs\n"
+
+DEFUN(cfg_gbproxy_match_imsi,
+      cfg_gbproxy_match_imsi_cmd,
+      "match-imsi (patching|routing) .REGEXP",
+      GBPROXY_MATCH_IMSI_STR
+      "Patch MS related information elements on match only\n"
+      "Route to the secondary SGSN on match only\n"
+      "Regular expression for the IMSI match\n")
+{
+	const char *filter = argv[1];
+	const char *err_msg = NULL;
+	struct gbproxy_match *match;
+	enum gbproxy_match_id match_id = get_string_value(match_ids, argv[0]);
+
+	OSMO_ASSERT(match_id >= GBPROX_MATCH_PATCHING &&
+		    match_id < GBPROX_MATCH_LAST);
+	match = &g_cfg->matches[match_id];
+
+	if (gbproxy_set_patch_filter(match, filter, &err_msg) != 0) {
+		vty_out(vty, "Match expression invalid: %s%s",
+			err_msg, VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
+	g_cfg->acquire_imsi = true;
+
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_gbproxy_no_match_imsi,
+      cfg_gbproxy_no_match_imsi_cmd,
+      "no match-imsi",
+      NO_STR GBPROXY_MATCH_IMSI_STR)
+{
+	enum gbproxy_match_id match_id;
+
+	for (match_id = 0; match_id < ARRAY_SIZE(g_cfg->matches); ++match_id)
+		gbproxy_clear_patch_filter(&g_cfg->matches[match_id]);
+
+	g_cfg->acquire_imsi = false;
+
+	return CMD_SUCCESS;
+}
+
+#define GBPROXY_CORE_APN_STR "Use this access point name (APN) for the backbone\n"
+#define GBPROXY_CORE_APN_ARG_STR "Replace APN by this string\n" "Remove APN\n"
+
+static int set_core_apn(struct vty *vty, const char *apn)
+{
+	int apn_len;
+
+	if (!apn) {
+		talloc_free(g_cfg->core_apn);
+		g_cfg->core_apn = NULL;
+		g_cfg->core_apn_size = 0;
+		return CMD_SUCCESS;
+	}
+
+	apn_len = strlen(apn);
+
+	if (apn_len >= 100) {
+		vty_out(vty, "APN string too long (max 99 chars)%s",
+			VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
+	if (apn_len == 0) {
+		talloc_free(g_cfg->core_apn);
+		/* TODO: replace NULL */
+		g_cfg->core_apn = talloc_zero_size(NULL, 2);
+		g_cfg->core_apn_size = 0;
+	} else {
+		/* TODO: replace NULL */
+		g_cfg->core_apn =
+			talloc_realloc_size(NULL, g_cfg->core_apn, apn_len + 1);
+		g_cfg->core_apn_size =
+			gprs_str_to_apn(g_cfg->core_apn, apn_len + 1, apn);
+	}
+
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_gbproxy_core_apn,
+      cfg_gbproxy_core_apn_cmd,
+      "core-access-point-name (APN|none)",
+      GBPROXY_CORE_APN_STR GBPROXY_CORE_APN_ARG_STR)
+{
+	if (strcmp(argv[0], "none") == 0)
+		return set_core_apn(vty, "");
+	else
+		return set_core_apn(vty, argv[0]);
+}
+
+DEFUN(cfg_gbproxy_no_core_apn,
+      cfg_gbproxy_no_core_apn_cmd,
+      "no core-access-point-name",
+      NO_STR GBPROXY_CORE_APN_STR)
+{
+	return set_core_apn(vty, NULL);
+}
+
+/* TODO: Remove the patch-ptmsi command, since P-TMSI patching is enabled
+ * automatically when needed. This command is only left for manual testing
+ * (e.g. doing P-TMSI patching without using a secondary SGSN)
+ */
+#define GBPROXY_PATCH_PTMSI_STR "Patch P-TMSI/TLLI\n"
+
+DEFUN(cfg_gbproxy_patch_ptmsi,
+      cfg_gbproxy_patch_ptmsi_cmd,
+      "patch-ptmsi",
+      GBPROXY_PATCH_PTMSI_STR)
+{
+	g_cfg->patch_ptmsi = true;
+
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_gbproxy_no_patch_ptmsi,
+      cfg_gbproxy_no_patch_ptmsi_cmd,
+      "no patch-ptmsi",
+      NO_STR GBPROXY_PATCH_PTMSI_STR)
+{
+	g_cfg->patch_ptmsi = false;
+
+	return CMD_SUCCESS;
+}
+
+/* TODO: Remove the acquire-imsi command, since that feature is enabled
+ * automatically when IMSI matching is enabled. This command is only left for
+ * manual testing (e.g. doing IMSI acquisition without IMSI based patching)
+ */
+#define GBPROXY_ACQUIRE_IMSI_STR "Acquire the IMSI before establishing a LLC connection (Experimental)\n"
+
+DEFUN(cfg_gbproxy_acquire_imsi,
+      cfg_gbproxy_acquire_imsi_cmd,
+      "acquire-imsi",
+      GBPROXY_ACQUIRE_IMSI_STR)
+{
+	g_cfg->acquire_imsi = true;
+
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_gbproxy_no_acquire_imsi,
+      cfg_gbproxy_no_acquire_imsi_cmd,
+      "no acquire-imsi",
+      NO_STR GBPROXY_ACQUIRE_IMSI_STR)
+{
+	g_cfg->acquire_imsi = false;
+
+	return CMD_SUCCESS;
+}
+
+#define GBPROXY_SECOND_SGSN_STR "Route matching LLC connections to a second SGSN (Experimental)\n"
+
+DEFUN(cfg_gbproxy_secondary_sgsn,
+      cfg_gbproxy_secondary_sgsn_cmd,
+      "secondary-sgsn nsei <0-65534>",
+      GBPROXY_SECOND_SGSN_STR
+      "NSEI to be used in the connection with the SGSN\n"
+      "The NSEI\n")
+{
+	unsigned int nsei = atoi(argv[0]);
+
+	if (g_cfg->nsip_sgsn_nsei == nsei) {
+		vty_out(vty, "Secondary SGSN NSEI %d conflicts with primary SGSN NSEI%s",
+			nsei, VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
+	g_cfg->route_to_sgsn2 = true;
+	g_cfg->nsip_sgsn2_nsei = nsei;
+
+	g_cfg->patch_ptmsi = true;
+
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_gbproxy_no_secondary_sgsn,
+      cfg_gbproxy_no_secondary_sgsn_cmd,
+      "no secondary-sgsn",
+      NO_STR GBPROXY_SECOND_SGSN_STR)
+{
+	g_cfg->route_to_sgsn2 = false;
+	g_cfg->nsip_sgsn2_nsei = 0xFFFF;
+
+	g_cfg->patch_ptmsi = false;
+
+	return CMD_SUCCESS;
+}
+
+#define GBPROXY_LINK_LIST_STR "Set TLLI list parameters\n"
+#define GBPROXY_LINK_STR "Set TLLI parameters\n"
+
+#define GBPROXY_CLEAN_STALE_TIMER_STR "Periodic timer to clean stale links\n"
+
+DEFUN(cfg_gbproxy_link_list_clean_stale_timer,
+      cfg_gbproxy_link_list_clean_stale_timer_cmd,
+      "link-list clean-stale-timer <1-999999>",
+      GBPROXY_LINK_LIST_STR GBPROXY_CLEAN_STALE_TIMER_STR
+      "Frequency at which the periodic timer is fired (in seconds)\n")
+{
+	struct gbproxy_peer *peer;
+	g_cfg->clean_stale_timer_freq = (unsigned int) atoi(argv[0]);
+
+	/* Re-schedule running timers soon in case prev frequency was really big
+	   and new frequency is desired to be lower. After initial run, periodic
+	   time is used. Use random() to avoid firing timers for all peers at
+	   the same time */
+	llist_for_each_entry(peer, &g_cfg->bts_peers, list)
+		osmo_timer_schedule(&peer->clean_stale_timer,
+					random() % 5, random() % 1000000);
+
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_gbproxy_link_list_no_clean_stale_timer,
+      cfg_gbproxy_link_list_no_clean_stale_timer_cmd,
+      "no link-list clean-stale-timer",
+      NO_STR GBPROXY_LINK_LIST_STR GBPROXY_CLEAN_STALE_TIMER_STR)
+
+{
+	struct gbproxy_peer *peer;
+	g_cfg->clean_stale_timer_freq = 0;
+
+	llist_for_each_entry(peer, &g_cfg->bts_peers, list)
+		osmo_timer_del(&peer->clean_stale_timer);
+
+	return CMD_SUCCESS;
+}
+
+#define GBPROXY_MAX_AGE_STR "Limit maximum age\n"
+
+DEFUN(cfg_gbproxy_link_list_max_age,
+      cfg_gbproxy_link_list_max_age_cmd,
+      "link-list max-age <1-999999>",
+      GBPROXY_LINK_LIST_STR GBPROXY_MAX_AGE_STR
+      "Maximum age in seconds\n")
+{
+	g_cfg->tlli_max_age = atoi(argv[0]);
+
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_gbproxy_link_list_no_max_age,
+      cfg_gbproxy_link_list_no_max_age_cmd,
+      "no link-list max-age",
+      NO_STR GBPROXY_LINK_LIST_STR GBPROXY_MAX_AGE_STR)
+{
+	g_cfg->tlli_max_age = 0;
+
+	return CMD_SUCCESS;
+}
+
+#define GBPROXY_MAX_LEN_STR "Limit list length\n"
+
+DEFUN(cfg_gbproxy_link_list_max_len,
+      cfg_gbproxy_link_list_max_len_cmd,
+      "link-list max-length <1-99999>",
+      GBPROXY_LINK_LIST_STR GBPROXY_MAX_LEN_STR
+      "Maximum number of logical links in the list\n")
+{
+	g_cfg->tlli_max_len = atoi(argv[0]);
+
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_gbproxy_link_list_no_max_len,
+      cfg_gbproxy_link_list_no_max_len_cmd,
+      "no link-list max-length",
+      NO_STR GBPROXY_LINK_LIST_STR GBPROXY_MAX_LEN_STR)
+{
+	g_cfg->tlli_max_len = 0;
+
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_gbproxy_link_list_keep_mode,
+      cfg_gbproxy_link_list_keep_mode_cmd,
+      "link-list keep-mode (never|re-attach|identified|always)",
+      GBPROXY_LINK_LIST_STR "How to keep entries for detached logical links\n"
+      "Discard entry immediately after detachment\n"
+      "Keep entry if a re-attachment has be requested\n"
+      "Keep entry if it associated with an IMSI\n"
+      "Don't discard entries after detachment\n")
+{
+	int val = get_string_value(keep_modes, argv[0]);
+	OSMO_ASSERT(val >= GBPROX_KEEP_NEVER && val <= GBPROX_KEEP_ALWAYS);
+	g_cfg->keep_link_infos = val;
+
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_gbproxy_link_stored_msgs_max_len,
+      cfg_gbproxy_link_stored_msgs_max_len_cmd,
+      "link stored-msgs-max-length <1-99999>",
+      GBPROXY_LINK_STR GBPROXY_MAX_LEN_STR
+      "Maximum number of msgb stored in the logical link waiting to acquire its IMSI\n")
+{
+	g_cfg->stored_msgs_max_len = (uint32_t) atoi(argv[0]);
+
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_gbproxy_link_no_stored_msgs_max_len,
+      cfg_gbproxy_link_no_stored_msgs_max_len_cmd,
+      "no link stored-msgs-max-length",
+      NO_STR GBPROXY_LINK_STR GBPROXY_MAX_LEN_STR)
+{
+	g_cfg->stored_msgs_max_len = 0;
+
+	return CMD_SUCCESS;
+}
+
+
+DEFUN(show_gbproxy, show_gbproxy_cmd, "show gbproxy [stats]",
+       SHOW_STR "Display information about the Gb proxy\n" "Show statistics\n")
+{
+	struct gbproxy_peer *peer;
+	int show_stats = argc >= 1;
+
+	if (show_stats)
+		vty_out_rate_ctr_group(vty, "", g_cfg->ctrg);
+
+	llist_for_each_entry(peer, &g_cfg->bts_peers, list) {
+		gbprox_vty_print_peer(vty, peer);
+
+		if (show_stats)
+			vty_out_rate_ctr_group(vty, "  ", peer->ctrg);
+	}
+	return CMD_SUCCESS;
+}
+
+DEFUN(show_gbproxy_links, show_gbproxy_links_cmd, "show gbproxy links",
+       SHOW_STR "Display information about the Gb proxy\n" "Show logical links\n")
+{
+	struct gbproxy_peer *peer;
+	char mi_buf[200];
+	time_t now;
+	struct timespec ts = {0,};
+
+	osmo_clock_gettime(CLOCK_MONOTONIC, &ts);
+	now = ts.tv_sec;
+
+	llist_for_each_entry(peer, &g_cfg->bts_peers, list) {
+		struct gbproxy_link_info *link_info;
+		struct gbproxy_patch_state *state = &peer->patch_state;
+
+		gbprox_vty_print_peer(vty, peer);
+
+		llist_for_each_entry(link_info, &state->logical_links, list) {
+			time_t age = now - link_info->timestamp;
+
+			if (link_info->imsi > 0) {
+				snprintf(mi_buf, sizeof(mi_buf), "(invalid)");
+				gsm48_mi_to_string(mi_buf, sizeof(mi_buf),
+						   link_info->imsi,
+						   link_info->imsi_len);
+			} else {
+				snprintf(mi_buf, sizeof(mi_buf), "(none)");
+			}
+			vty_out(vty, "  TLLI %08x, IMSI %s, AGE %d",
+				link_info->tlli.current, mi_buf, (int)age);
+
+			if (link_info->stored_msgs_len)
+				vty_out(vty, ", STORED %"PRIu32"/%"PRIu32,
+					link_info->stored_msgs_len,
+					g_cfg->stored_msgs_max_len);
+
+			if (g_cfg->route_to_sgsn2)
+				vty_out(vty, ", SGSN NSEI %d",
+					link_info->sgsn_nsei);
+
+			if (link_info->is_deregistered)
+				vty_out(vty, ", DE-REGISTERED");
+
+			vty_out(vty, "%s", VTY_NEWLINE);
+		}
+	}
+	return CMD_SUCCESS;
+}
+
+DEFUN(delete_gb_bvci, delete_gb_bvci_cmd,
+	"delete-gbproxy-peer <0-65534> bvci <2-65534>",
+	"Delete a GBProxy peer by NSEI and optionally BVCI\n"
+	"NSEI number\n"
+	"Only delete peer with a matching BVCI\n"
+	"BVCI number\n")
+{
+	const uint16_t nsei = atoi(argv[0]);
+	const uint16_t bvci = atoi(argv[1]);
+	int counter;
+
+	counter = gbproxy_cleanup_peers(g_cfg, nsei, bvci);
+
+	if (counter == 0) {
+		vty_out(vty, "BVC not found%s", VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
+	return CMD_SUCCESS;
+}
+
+DEFUN(delete_gb_nsei, delete_gb_nsei_cmd,
+	"delete-gbproxy-peer <0-65534> (only-bvc|only-nsvc|all) [dry-run]",
+	"Delete a GBProxy peer by NSEI and optionally BVCI\n"
+	"NSEI number\n"
+	"Only delete BSSGP connections (BVC)\n"
+	"Only delete dynamic NS connections (NS-VC)\n"
+	"Delete BVC and dynamic NS connections\n"
+	"Show what would be deleted instead of actually deleting\n"
+	)
+{
+	const uint16_t nsei = atoi(argv[0]);
+	const char *mode = argv[1];
+	int dry_run = argc > 2;
+	int delete_bvc = 0;
+	int delete_nsvc = 0;
+	int counter;
+
+	if (strcmp(mode, "only-bvc") == 0)
+		delete_bvc = 1;
+	else if (strcmp(mode, "only-nsvc") == 0)
+		delete_nsvc = 1;
+	else
+		delete_bvc = delete_nsvc = 1;
+
+	if (delete_bvc) {
+		if (!dry_run)
+			counter = gbproxy_cleanup_peers(g_cfg, nsei, 0);
+		else {
+			struct gbproxy_peer *peer;
+			counter = 0;
+			llist_for_each_entry(peer, &g_cfg->bts_peers, list) {
+				if (peer->nsei != nsei)
+					continue;
+
+				vty_out(vty, "BVC: ");
+				gbprox_vty_print_peer(vty, peer);
+				counter += 1;
+			}
+		}
+		vty_out(vty, "%sDeleted %d BVC%s",
+			dry_run ? "Not " : "", counter, VTY_NEWLINE);
+	}
+
+	if (delete_nsvc) {
+		struct gprs_ns_inst *nsi = g_cfg->nsi;
+		struct gprs_nsvc *nsvc, *nsvc2;
+
+		counter = 0;
+		llist_for_each_entry_safe(nsvc, nsvc2, &nsi->gprs_nsvcs, list) {
+			if (nsvc->nsei != nsei)
+				continue;
+			if (nsvc->persistent)
+				continue;
+
+			if (!dry_run)
+				gprs_nsvc_delete(nsvc);
+			else
+				vty_out(vty, "NS-VC: NSEI %5u, NS-VCI %5u, "
+					"remote %s%s",
+					nsvc->nsei, nsvc->nsvci,
+					gprs_ns_ll_str(nsvc), VTY_NEWLINE);
+			counter += 1;
+		}
+		vty_out(vty, "%sDeleted %d NS-VC%s",
+			dry_run ? "Not " : "", counter, VTY_NEWLINE);
+	}
+
+	return CMD_SUCCESS;
+}
+
+#define GBPROXY_DELETE_LINK_STR \
+	"Delete a GBProxy logical link entry by NSEI and identification\nNSEI number\n"
+
+DEFUN(delete_gb_link_by_id, delete_gb_link_by_id_cmd,
+	"delete-gbproxy-link <0-65534> (tlli|imsi|sgsn-nsei) IDENT",
+	GBPROXY_DELETE_LINK_STR
+	"Delete entries with a matching TLLI (hex)\n"
+	"Delete entries with a matching IMSI\n"
+	"Delete entries with a matching SGSN NSEI\n"
+	"Identification to match\n")
+{
+	const uint16_t nsei = atoi(argv[0]);
+	enum {MATCH_TLLI = 't', MATCH_IMSI = 'i', MATCH_SGSN = 's'} match;
+	uint32_t ident = 0;
+	const char *imsi = NULL;
+	struct gbproxy_peer *peer = 0;
+	struct gbproxy_link_info *link_info, *nxt;
+	struct gbproxy_patch_state *state;
+	char mi_buf[200];
+	int found = 0;
+
+	match = argv[1][0];
+
+	switch (match) {
+	case MATCH_TLLI: ident = strtoll(argv[2], NULL, 16); break;
+	case MATCH_IMSI: imsi = argv[2]; break;
+	case MATCH_SGSN: ident = strtoll(argv[2], NULL, 0); break;
+	};
+
+	peer = gbproxy_peer_by_nsei(g_cfg, nsei);
+	if (!peer) {
+		vty_out(vty, "Didn't find peer with NSEI %d%s",
+			nsei, VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
+	state = &peer->patch_state;
+
+	llist_for_each_entry_safe(link_info, nxt, &state->logical_links, list) {
+		switch (match) {
+		case MATCH_TLLI:
+			if (link_info->tlli.current != ident)
+				continue;
+			break;
+		case MATCH_SGSN:
+			if (link_info->sgsn_nsei != ident)
+				continue;
+			break;
+		case MATCH_IMSI:
+			if (!link_info->imsi)
+				continue;
+			mi_buf[0] = '\0';
+			gsm48_mi_to_string(mi_buf, sizeof(mi_buf),
+					   link_info->imsi,
+					   link_info->imsi_len);
+
+			if (strcmp(mi_buf, imsi) != 0)
+				continue;
+			break;
+		}
+
+		vty_out(vty, "Deleting link with TLLI %08x%s", link_info->tlli.current,
+			VTY_NEWLINE);
+		gbproxy_delete_link_info(peer, link_info);
+		found += 1;
+	}
+
+	if (!found && argc >= 2) {
+		vty_out(vty, "Didn't find link entry with %s %s%s",
+			argv[1], argv[2], VTY_NEWLINE);
+	}
+
+	return CMD_SUCCESS;
+}
+
+DEFUN(delete_gb_link, delete_gb_link_cmd,
+	"delete-gbproxy-link <0-65534> (stale|de-registered)",
+	GBPROXY_DELETE_LINK_STR
+	"Delete stale entries\n"
+	"Delete de-registered entries\n")
+{
+	const uint16_t nsei = atoi(argv[0]);
+	enum {MATCH_STALE = 's', MATCH_DEREGISTERED = 'd'} match;
+	struct gbproxy_peer *peer = 0;
+	struct gbproxy_link_info *link_info, *nxt;
+	struct gbproxy_patch_state *state;
+	time_t now;
+	struct timespec ts = {0,};
+
+	int found = 0;
+
+	match = argv[1][0];
+
+	peer = gbproxy_peer_by_nsei(g_cfg, nsei);
+	if (!peer) {
+		vty_out(vty, "Didn't find peer with NSEI %d%s",
+			nsei, VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
+	state = &peer->patch_state;
+
+	osmo_clock_gettime(CLOCK_MONOTONIC, &ts);
+	now = ts.tv_sec;
+
+	if (match == MATCH_STALE) {
+		found = gbproxy_remove_stale_link_infos(peer, now);
+		if (found)
+			vty_out(vty, "Deleted %d stale logical link%s%s",
+				found, found == 1 ? "" : "s", VTY_NEWLINE);
+	} else {
+		llist_for_each_entry_safe(link_info, nxt,
+					  &state->logical_links, list) {
+			if (!link_info->is_deregistered)
+				continue;
+
+			gbproxy_delete_link_info(peer, link_info);
+			found += 1;
+		}
+	}
+
+	if (found)
+		vty_out(vty, "Deleted %d %s logical link%s%s",
+			found, argv[1], found == 1 ? "" : "s", VTY_NEWLINE);
+
+	return CMD_SUCCESS;
+}
+
+/*
+ * legacy commands to provide an upgrade path from "broken" releases
+ * or pre-releases
+ */
+DEFUN_DEPRECATED(cfg_gbproxy_broken_apn_match,
+      cfg_gbproxy_broken_apn_match_cmd,
+      "core-access-point-name none match-imsi .REGEXP",
+      GBPROXY_CORE_APN_STR GBPROXY_MATCH_IMSI_STR "Remove APN\n"
+      "Patch MS related information elements on match only\n"
+      "Route to the secondary SGSN on match only\n"
+      "Regular expression for the IMSI match\n")
+{
+	const char *filter = argv[0];
+	const char *err_msg = NULL;
+	struct gbproxy_match *match;
+	enum gbproxy_match_id match_id = get_string_value(match_ids, "patching");
+
+	/* apply APN none */
+	set_core_apn(vty, "");
+
+	/* do the matching... with copy and paste */
+	OSMO_ASSERT(match_id >= GBPROX_MATCH_PATCHING &&
+		    match_id < GBPROX_MATCH_LAST);
+	match = &g_cfg->matches[match_id];
+
+	if (gbproxy_set_patch_filter(match, filter, &err_msg) != 0) {
+		vty_out(vty, "Match expression invalid: %s%s",
+			err_msg, VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
+	g_cfg->acquire_imsi = true;
+
+	return CMD_SUCCESS;
+}
+
+#define GBPROXY_TLLI_LIST_STR "Set TLLI list parameters\n"
+#define GBPROXY_MAX_LEN_STR "Limit list length\n"
+DEFUN_DEPRECATED(cfg_gbproxy_depr_tlli_list_max_len,
+      cfg_gbproxy_depr_tlli_list_max_len_cmd,
+      "tlli-list max-length <1-99999>",
+      GBPROXY_TLLI_LIST_STR GBPROXY_MAX_LEN_STR
+      "Maximum number of TLLIs in the list\n")
+{
+	g_cfg->tlli_max_len = atoi(argv[0]);
+
+	return CMD_SUCCESS;
+}
+
+int gbproxy_vty_init(void)
+{
+	install_element_ve(&show_gbproxy_cmd);
+	install_element_ve(&show_gbproxy_links_cmd);
+
+	install_element(ENABLE_NODE, &delete_gb_bvci_cmd);
+	install_element(ENABLE_NODE, &delete_gb_nsei_cmd);
+	install_element(ENABLE_NODE, &delete_gb_link_by_id_cmd);
+	install_element(ENABLE_NODE, &delete_gb_link_cmd);
+
+	install_element(CONFIG_NODE, &cfg_gbproxy_cmd);
+	install_node(&gbproxy_node, config_write_gbproxy);
+	install_element(GBPROXY_NODE, &cfg_nsip_sgsn_nsei_cmd);
+	install_element(GBPROXY_NODE, &cfg_gbproxy_core_mcc_cmd);
+	install_element(GBPROXY_NODE, &cfg_gbproxy_core_mnc_cmd);
+	install_element(GBPROXY_NODE, &cfg_gbproxy_match_imsi_cmd);
+	install_element(GBPROXY_NODE, &cfg_gbproxy_core_apn_cmd);
+	install_element(GBPROXY_NODE, &cfg_gbproxy_secondary_sgsn_cmd);
+	install_element(GBPROXY_NODE, &cfg_gbproxy_patch_ptmsi_cmd);
+	install_element(GBPROXY_NODE, &cfg_gbproxy_acquire_imsi_cmd);
+	install_element(GBPROXY_NODE, &cfg_gbproxy_link_list_clean_stale_timer_cmd);
+	install_element(GBPROXY_NODE, &cfg_gbproxy_link_list_max_age_cmd);
+	install_element(GBPROXY_NODE, &cfg_gbproxy_link_list_max_len_cmd);
+	install_element(GBPROXY_NODE, &cfg_gbproxy_link_list_keep_mode_cmd);
+	install_element(GBPROXY_NODE, &cfg_gbproxy_link_stored_msgs_max_len_cmd);
+	install_element(GBPROXY_NODE, &cfg_gbproxy_no_core_mcc_cmd);
+	install_element(GBPROXY_NODE, &cfg_gbproxy_no_core_mnc_cmd);
+	install_element(GBPROXY_NODE, &cfg_gbproxy_no_match_imsi_cmd);
+	install_element(GBPROXY_NODE, &cfg_gbproxy_no_core_apn_cmd);
+	install_element(GBPROXY_NODE, &cfg_gbproxy_no_secondary_sgsn_cmd);
+	install_element(GBPROXY_NODE, &cfg_gbproxy_no_patch_ptmsi_cmd);
+	install_element(GBPROXY_NODE, &cfg_gbproxy_no_acquire_imsi_cmd);
+	install_element(GBPROXY_NODE, &cfg_gbproxy_link_list_no_clean_stale_timer_cmd);
+	install_element(GBPROXY_NODE, &cfg_gbproxy_link_list_no_max_age_cmd);
+	install_element(GBPROXY_NODE, &cfg_gbproxy_link_list_no_max_len_cmd);
+	install_element(GBPROXY_NODE, &cfg_gbproxy_link_no_stored_msgs_max_len_cmd);
+
+	/* broken or deprecated to allow an upgrade path */
+	install_element(GBPROXY_NODE, &cfg_gbproxy_broken_apn_match_cmd);
+	install_element(GBPROXY_NODE, &cfg_gbproxy_depr_tlli_list_max_len_cmd);
+
+	return 0;
+}
+
+int gbproxy_parse_config(const char *config_file, struct gbproxy_config *cfg)
+{
+	int rc;
+
+	g_cfg = cfg;
+	rc = vty_read_config_file(config_file, NULL);
+	if (rc < 0) {
+		fprintf(stderr, "Failed to parse the config file: '%s'\n", config_file);
+		return rc;
+	}
+
+	return 0;
+}