diff --git a/openbsc/src/gprs/gtphub_ares.c b/openbsc/src/gprs/gtphub_ares.c
new file mode 100644
index 0000000..4cacf88
--- /dev/null
+++ b/openbsc/src/gprs/gtphub_ares.c
@@ -0,0 +1,218 @@
+/* GTP Hub Implementation */
+
+/* (C) 2015 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ * All Rights Reserved
+ *
+ * gtphub_ares.c.
+ *
+ * This file is kept separate so that these functions can be wrapped for
+ * gtphub_test.c. When a function and its callers are in the same compilational
+ * unit, the wrappability may be optimized away.
+ *
+ * Author: Neels Hofmeyr
+ *
+ * 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 <string.h>
+#include <unistd.h>
+
+#include <openbsc/gtphub.h>
+#include <openbsc/debug.h>
+
+#include <osmocom/core/utils.h>
+#include <osmocom/gsm/apn.h>
+
+/* TODO split GRX ares from sgsn into a separate struct and allow use without
+ * globals. */
+#include <openbsc/sgsn.h>
+extern struct sgsn_instance *sgsn;
+
+struct sgsn_instance sgsn_inst = { 0 };
+struct sgsn_instance *sgsn = &sgsn_inst;
+
+extern void *osmo_gtphub_ctx;
+
+int gtphub_ares_init(struct gtphub *hub)
+{
+	return sgsn_ares_init(sgsn);
+}
+
+struct ggsn_lookup {
+	struct llist_head entry;
+	struct expiring_item expiry_entry;
+
+	struct gtphub *hub;
+
+	char imsi_str[GSM_IMSI_LENGTH];
+	char apn_ni_str[GSM_APN_LENGTH];
+	char apn_oi_str[GSM_APN_LENGTH];
+	int have_3dig_mnc;
+};
+
+static int start_ares_query(struct ggsn_lookup *lookup);
+
+static void ggsn_lookup_cb(void *arg, int status, int timeouts,
+			   struct hostent *hostent)
+{
+	struct ggsn_lookup *lookup = arg;
+	LOGP(DGTPHUB, LOGL_NOTICE, "ggsn_lookup_cb(%p / %p)", lookup,
+	     &lookup->expiry_entry);
+
+	if (status != ARES_SUCCESS) {
+		LOGP(DGTPHUB, LOGL_ERROR, "DNS query failed.\n");
+
+		/* Need to try with three digits now */
+		if (!lookup->have_3dig_mnc) {
+			lookup->have_3dig_mnc = 1;
+			if (start_ares_query(lookup) == 0)
+				return;
+		}
+
+		LOGP(DGTPHUB, LOGL_ERROR, "Failed to resolve GGSN. (%p)\n",
+		     lookup);
+		goto remove_from_queue;
+	}
+
+	struct gsn_addr resolved_addr;
+	if (hostent->h_length > sizeof(resolved_addr.buf)) {
+		LOGP(DGTPHUB, LOGL_ERROR, "Addr size too large: %d > %d\n",
+		     (int)hostent->h_length, (int)sizeof(resolved_addr.buf));
+		goto remove_from_queue;
+	}
+
+	/* Get the first addr from the list */
+	char *addr0 = hostent->h_addr_list[0];
+	if (!addr0) {
+		LOGP(DGTPHUB, LOGL_ERROR, "No host address.\n");
+		goto remove_from_queue;
+	}
+
+	memcpy(resolved_addr.buf, addr0, hostent->h_length);
+	resolved_addr.len = hostent->h_length;
+
+	LOGP(DGTPHUB, LOGL_NOTICE, "resolved addr %s\n",
+	     osmo_hexdump((unsigned char*)&resolved_addr,
+			  sizeof(resolved_addr)));
+
+	gtphub_resolved_ggsn(lookup->hub, lookup->apn_oi_str, &resolved_addr,
+			     gtphub_now());
+
+remove_from_queue:
+	LOGP(DGTPHUB, LOGL_ERROR, "Removing GGSN lookup. (%p / %p)\n", lookup,
+	     &lookup->expiry_entry);
+	expiring_item_del(&lookup->expiry_entry);
+}
+
+static void make_addr_str(struct ggsn_lookup *lookup)
+{
+	char *apn_oi_str;
+	apn_oi_str = osmo_apn_qualify_from_imsi(lookup->imsi_str,
+						lookup->apn_ni_str,
+						lookup->have_3dig_mnc);
+	strncpy(lookup->apn_oi_str, apn_oi_str, sizeof(lookup->apn_oi_str));
+	lookup->apn_oi_str[sizeof(lookup->apn_oi_str)-1] = '\0';
+}
+
+static int start_ares_query(struct ggsn_lookup *lookup)
+{
+	LOGP(DGTPHUB, LOGL_DEBUG, "Going to query %s (%p / %p)\n",
+	     lookup->apn_oi_str, lookup, &lookup->expiry_entry);
+
+	int rc = sgsn_ares_query(sgsn, lookup->apn_oi_str, ggsn_lookup_cb,
+				 lookup);
+	if (rc != 0)
+		LOGP(DGTPHUB, LOGL_ERROR, "Failed to start ares query.\n");
+	return rc;
+}
+
+static void ggsn_lookup_del_cb(struct expiring_item *expi)
+{
+	struct ggsn_lookup *lookup;
+	lookup = container_of(expi, struct ggsn_lookup, expiry_entry);
+
+	LOGP(DGTPHUB, LOGL_NOTICE, "ggsn_lookup_del_cb(%p / %p)\n", lookup,
+	     expi);
+
+	lookup->expiry_entry.del_cb = 0;
+	expiring_item_del(expi);
+
+	llist_del(&lookup->entry);
+	talloc_free(lookup);
+}
+
+struct gtphub_peer_port *gtphub_resolve_ggsn_addr(struct gtphub *hub,
+						  const char *imsi_str,
+						  const char *apn_ni_str)
+{
+	OSMO_ASSERT(imsi_str);
+	OSMO_ASSERT(apn_ni_str);
+
+	struct ggsn_lookup *lookup = talloc_zero(osmo_gtphub_ctx,
+						 struct ggsn_lookup);
+	OSMO_ASSERT(lookup);
+
+	LOGP(DGTPHUB, LOGL_NOTICE, "Request to resolve IMSI"
+	     " '%s' with APN-NI '%s' (%p / %p)\n",
+	     imsi_str, apn_ni_str, lookup, &lookup->expiry_entry);
+
+	expiring_item_init(&lookup->expiry_entry);
+	lookup->hub = hub;
+
+	strncpy(lookup->imsi_str, imsi_str, sizeof(lookup->imsi_str));
+	lookup->imsi_str[sizeof(lookup->imsi_str)-1] = '\0';
+
+	strncpy(lookup->apn_ni_str, apn_ni_str, sizeof(lookup->apn_ni_str));
+	lookup->apn_ni_str[sizeof(lookup->apn_ni_str)-1] = '\0';
+
+	make_addr_str(lookup);
+
+	LOGP(DGTPHUB, LOGL_NOTICE, "looking for active queries...\n");
+	struct ggsn_lookup *active;
+	llist_for_each_entry(active, &hub->ggsn_lookups, entry) {
+		if (strncmp(active->apn_oi_str, lookup->apn_oi_str,
+			    sizeof(lookup->apn_oi_str)) == 0) {
+			/* A query already pending. Just tip our hat. */
+			return NULL;
+		}
+	}
+
+	LOGP(DGTPHUB, LOGL_NOTICE, "looking for already resolved GGSNs...\n");
+	struct gtphub_resolved_ggsn *resolved;
+	llist_for_each_entry(resolved, &hub->resolved_ggsns, entry) {
+		if (strncmp(resolved->apn_oi_str, lookup->apn_oi_str,
+			    sizeof(lookup->apn_oi_str)) == 0) {
+			/* Already resolved. */
+			return resolved->peer;
+		}
+	}
+
+	/* Kick off a resolution, but so far return nothing. The hope is that
+	 * the peer will resend the request (a couple of times), and by then
+	 * the GGSN will be resolved. */
+	LOGP(DGTPHUB, LOGL_NOTICE, "kick off resolution.\n");
+
+	llist_add(&lookup->entry, &hub->ggsn_lookups);
+
+	lookup->expiry_entry.del_cb = ggsn_lookup_del_cb;
+	expiry_add(&hub->expire_seq_maps, &lookup->expiry_entry, gtphub_now());
+
+	start_ares_query(lookup);
+	LOGP(DGTPHUB, LOGL_NOTICE, "Resolving %s %s ..."
+	     " (Returning failure, hoping for a retry"
+	     "once resolution has concluded)\n",
+	     imsi_str, apn_ni_str);
+
+	return NULL;
+}