Messages in this thread Patch in this message |  | | From | "Svenning Soerensen" <> | Subject | Problem with PMTU discovery on ICMP packets | Date | Sat, 5 May 2001 13:36:32 +0200 |
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Hi there,
I think there is a bug in the 2.4 icmp code regarding PMTU discovery. It seems to be inconsistent between reboots: at one boot echo replies always have the DF bit set, while after another boot they don't, indicating that this is caused by an uninitialized parameter. Even 'echo 1 > /proc/sys/net/ipv4/ip_no_pmtu_disc' doesn't change this behaviour.
I can't think of any legitimate reasons for doing PMTU discovery on ICMP packets, and since it actually in some situations breaks ping in combination with FreeS/WAN (I can elaborate, if anyone is interested), I would suggest to turn it off in a consistent manner. The patch below (against 2.4.4) should accomplish this.
Svenning
--- linux/net/ipv4/icmp.c 2001/04/28 12:30:34 1.1.1.2 +++ linux/net/ipv4/icmp.c 2001/05/05 11:06:41 @@ -1006,6 +1006,7 @@ icmp_socket->sk->allocation=GFP_ATOMIC; icmp_socket->sk->sndbuf = SK_WMEM_MAX*2; icmp_socket->sk->protinfo.af_inet.ttl = MAXTTL; + icmp_socket->sk->protinfo.af_inet.pmtudisc = IP_PMTUDISC_DONT; /* Unhash it so that IP input processing does not even * see it, we do not wish this socket to see incoming - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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