diff --git a/src/gsmtap_util.c b/src/gsmtap_util.c
new file mode 100644
index 0000000..5da4369
--- /dev/null
+++ b/src/gsmtap_util.c
@@ -0,0 +1,185 @@
+/* GSMTAP output for Osmocom Layer2 (will only work on the host PC) */
+/*
+ * (C) 2010 by Harald Welte <laforge@gnumonks.org>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+
+#include "../config.h"
+
+#ifdef HAVE_SYS_SELECT_H
+
+#include <osmocore/gsmtap_util.h>
+#include <osmocore/logging.h>
+#include <osmocore/protocol/gsm_04_08.h>
+#include <osmocore/gsmtap.h>
+#include <osmocore/msgb.h>
+#include <osmocore/rsl.h>
+#include <osmocore/select.h>
+
+#include <arpa/inet.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+
+#include <stdio.h>
+#include <unistd.h>
+#include <stdint.h>
+#include <string.h>
+#include <errno.h>
+
+static struct bsc_fd gsmtap_bfd = { .fd = -1 };
+static LLIST_HEAD(gsmtap_txqueue);
+
+uint8_t chantype_rsl2gsmtap(uint8_t rsl_chantype, uint8_t link_id)
+{
+	uint8_t ret = GSMTAP_CHANNEL_UNKNOWN;
+
+	switch (rsl_chantype) {
+	case RSL_CHAN_Bm_ACCHs:
+		ret = GSMTAP_CHANNEL_TCH_F;
+		break;
+	case RSL_CHAN_Lm_ACCHs:
+		ret = GSMTAP_CHANNEL_TCH_H;
+		break;
+	case RSL_CHAN_SDCCH4_ACCH:
+		ret = GSMTAP_CHANNEL_SDCCH4;
+		break;
+	case RSL_CHAN_SDCCH8_ACCH:
+		ret = GSMTAP_CHANNEL_SDCCH8;
+		break;
+	case RSL_CHAN_BCCH:
+		ret = GSMTAP_CHANNEL_BCCH;
+		break;
+	case RSL_CHAN_RACH:
+		ret = GSMTAP_CHANNEL_RACH;
+		break;
+	case RSL_CHAN_PCH_AGCH:
+		/* it could also be AGCH... */
+		ret = GSMTAP_CHANNEL_PCH;
+		break;
+	}
+
+	if (link_id & 0x40)
+		ret |= GSMTAP_CHANNEL_ACCH;
+
+	return ret;
+}
+
+/* receive a message from L1/L2 and put it in GSMTAP */
+int gsmtap_sendmsg(uint16_t arfcn, uint8_t ts, uint8_t chan_type, uint8_t ss,
+		   uint32_t fn, int8_t signal_dbm, uint8_t snr,
+		   const uint8_t *data, unsigned int len)
+{
+	struct msgb *msg;
+	struct gsmtap_hdr *gh;
+	uint8_t *dst;
+
+	/* gsmtap was never initialized, so don't try to send anything */
+	if (gsmtap_bfd.fd == -1)
+		return 0;
+
+	msg = msgb_alloc(sizeof(*gh) + len, "gsmtap_tx");
+	if (!msg)
+		return -ENOMEM;
+
+	gh = (struct gsmtap_hdr *) msgb_put(msg, sizeof(*gh));
+
+	gh->version = GSMTAP_VERSION;
+	gh->hdr_len = sizeof(*gh)/4;
+	gh->type = GSMTAP_TYPE_UM;
+	gh->timeslot = ts;
+	gh->sub_slot = ss;
+	gh->arfcn = htons(arfcn);
+	gh->snr_db = snr;
+	gh->signal_dbm = signal_dbm;
+	gh->frame_number = htonl(fn);
+	gh->sub_type = chan_type;
+	gh->antenna_nr = 0;
+
+	dst = msgb_put(msg, len);
+	memcpy(dst, data, len);
+
+	msgb_enqueue(&gsmtap_txqueue, msg);
+	gsmtap_bfd.when |= BSC_FD_WRITE;
+
+	return 0;
+}
+
+/* Callback from select layer if we can write to the socket */
+static int gsmtap_fd_cb(struct bsc_fd *fd, unsigned int flags)
+{
+	struct msgb *msg;
+	int rc;
+
+	if (!(flags & BSC_FD_WRITE))
+		return 0;
+
+	msg = msgb_dequeue(&gsmtap_txqueue);
+	if (!msg) {
+		/* no more messages in the queue, disable READ cb */
+		gsmtap_bfd.when = 0;
+		return 0;
+	}
+	rc = write(gsmtap_bfd.fd, msg->data, msg->len);
+	if (rc < 0) {
+		perror("writing msgb to gsmtap fd");
+		msgb_free(msg);
+		return rc;
+	}
+	if (rc != msg->len) {
+		perror("short write to gsmtap fd");
+		msgb_free(msg);
+		return -EIO;
+	}
+
+	msgb_free(msg);
+	return 0;
+}
+
+int gsmtap_init(uint32_t dst_ip)
+{
+	int rc;
+	struct sockaddr_in sin;
+
+	sin.sin_family = AF_INET;
+	sin.sin_port = htons(GSMTAP_UDP_PORT);
+	sin.sin_addr.s_addr = htonl(dst_ip);
+
+	/* FIXME: create socket */
+	rc = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
+	if (rc < 0) {
+		perror("creating UDP socket");
+		return rc;
+	}
+	gsmtap_bfd.fd = rc;
+	rc = connect(rc, (struct sockaddr *)&sin, sizeof(sin));
+	if (rc < 0) {
+		perror("connecting UDP socket");
+		close(gsmtap_bfd.fd);
+		gsmtap_bfd.fd = 0;
+		return rc;
+	}
+
+	gsmtap_bfd.when = BSC_FD_WRITE;
+	gsmtap_bfd.cb = gsmtap_fd_cb;
+	gsmtap_bfd.data = NULL;
+
+	return bsc_register_fd(&gsmtap_bfd);
+}
+
+#endif /* HAVE_SYS_SELECT_H */