--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -1050,6 +1050,8 @@ DEF("net", HAS_ARG, QEMU_OPTION_net,
     "                connect the user mode network stack to VLAN 'n', configure its\n"
     "                DHCP server and enabled optional services\n"
 #endif
+    "-net udp[,vlan=n],sport=sport,dport=dport,daddr=host\n"
+    "                connect the vlan 'n' to a udp host (for dynamips/pemu/GNS3)\n"
 #ifdef _WIN32
     "-net tap[,vlan=n][,name=str],ifname=name\n"
     "                connect the host TAP network interface to VLAN 'n'\n"