diff --git a/cfg.lex b/cfg.lex
index db3b6deb9de..73e4b83c48f 100644
--- a/cfg.lex
+++ b/cfg.lex
@@ -326,6 +326,7 @@ CR			\n
 
 ANY		"any"
 ANYCAST "anycast"
+FRAG "frag"
 
 
 COM_LINE	#
@@ -581,6 +582,7 @@ SPACE		[ ]
 <INITIAL>{CR}		{ count();/* return CR;*/ }
 <INITIAL>{ANY}		{ count(); return ANY; }
 <INITIAL>{ANYCAST}	{ count(); return ANYCAST; }
+<INITIAL>{FRAG}		{ count(); return FRAG; }
 <INITIAL>{SLASH}	{ count(); return SLASH; }
 <INITIAL>{SCALE_UP_TO}		{ count(); return SCALE_UP_TO; }
 <INITIAL>{SCALE_DOWN_TO}	{ count(); return SCALE_DOWN_TO; }
diff --git a/cfg.y b/cfg.y
index 947d5dbae44..d23d7a25cc8 100644
--- a/cfg.y
+++ b/cfg.y
@@ -430,6 +430,7 @@ extern int cfg_parse_only_routes;
 %token COLON
 %token ANY
 %token ANYCAST
+%token FRAG
 %token SCRIPTVARERR
 %token SCALE_UP_TO
 %token SCALE_DOWN_TO
@@ -636,6 +637,9 @@ listen_id_def:	listen_id					{ IFOR();
 socket_def_param: ANYCAST { IFOR();
 					p_tmp.flags |= SI_IS_ANYCAST;
 					}
+				| FRAG { IFOR();
+					p_tmp.flags |= SI_FRAG;
+					}
 				| USE_WORKERS NUMBER { IFOR();
 					p_tmp.workers=$2;
 					}
diff --git a/ip_addr.h b/ip_addr.h
index c449ef7fa0f..438b7779db0 100644
--- a/ip_addr.h
+++ b/ip_addr.h
@@ -89,7 +89,7 @@ union sockaddr_union{
 
 
 enum si_flags { SI_NONE=0, SI_IS_IP=1, SI_IS_LO=2, SI_IS_MCAST=4,
-	SI_IS_ANYCAST=8 };
+	SI_IS_ANYCAST=8, SI_FRAG=16 };
 
 struct receive_info {
 	struct ip_addr src_ip;
diff --git a/net/net_udp.c b/net/net_udp.c
index 34e2a9fb778..dfb3a4ec5bc 100644
--- a/net/net_udp.c
+++ b/net/net_udp.c
@@ -179,6 +179,13 @@ int udp_init_listener(struct socket_info *si, int status_flags)
 		LM_ERR("setsockopt: %s\n", strerror(errno));
 		goto error;
 	}
+
+	if (si->flags & SI_FRAG) {
+		/* no DF */
+		optval = IP_PMTUDISC_DONT;
+		setsockopt(si->socket, IPPROTO_IP, IP_MTU_DISCOVER, (void*)&optval, sizeof(optval));
+	}
+
 	/* tos */
 	optval=tos;
 	if (addr->s.sa_family==AF_INET6){
diff --git a/net/trans.c b/net/trans.c
index 3aee25f7b85..e18f7f38235 100644
--- a/net/trans.c
+++ b/net/trans.c
@@ -264,9 +264,10 @@ void print_all_socket_lists(void)
 			continue;
 
 		for (si = protos[i].listeners; si; si = si->next)
-			printf("             %s: %s [%s]:%s%s%s\n", protos[i].name,
+			printf("             %s: %s [%s]:%s%s%s%s\n", protos[i].name,
 					si->name.s, si->address_str.s, si->port_no_str.s,
 					si->flags & SI_IS_MCAST ? " mcast" : "",
+					si->flags & SI_FRAG ? " allow_fragments" : "",
 					is_anycast(si)? " anycast" : "");
 	}
 }