--- /dev/null
+Patch to stop l2tpd setting the DF bit on each of the packets it sends.
+Apart from not being useful with L2TP, this also prevents interoperating
+with Cisco IOS over IPSEC.
+
+--- l2tpd-0.70-pre20031121.orig/network.c.orig 2006-04-11 08:50:38.000000000 +0100
++++ l2tpd-0.70-pre20031121.orig/network.c 2006-04-11 08:58:18.000000000 +0100
+@@ -56,6 +56,18 @@
+ __FUNCTION__);
+ return -EINVAL;
+ };
++#ifdef IP_MTU_DISCOVER
++#ifdef IP_PMTUDISC_DONT
++ {
++ /* Don't set DF bit on outbound packets */
++ int val = IP_PMTUDISC_DONT;
++ if (setsockopt(server_socket, IPPROTO_IP, IP_MTU_DISCOVER, &val, sizeof(val)) < 0)
++ {
++ log (LOG_LOG, "Failed to disable PMTU discovery\n");
++ }
++ }
++#endif
++#endif
+ /* L2TP/IPSec: Set up SA for listening port here? NTB 20011015
+ */
+ if (bind (server_socket, (struct sockaddr *) &server, sizeof (server)))