[Openswan Users] ICMP Type 3, Code 4, MTU 0?

Paul Wouters paul at xelerance.com
Mon Apr 17 02:24:14 CEST 2006

On Thu, 13 Apr 2006, Peter McGill wrote:

> Windows receives ICMP Type 3 (Destination Unreachable), Code 4 (Must
> Fragment), MTU 0
> Windows adjusts the routes (presumably to lower the MTU)
> Contivity Client complains about route change and disconnects (for security)
> sheridan (Linux) appears to be generating the ICMP messages.
> They first show up on sheridan's eth0 interface, but not on the ipsec0
> interface.
> I have upgraded both the Kernel and OpenSWAN on sheridan since the last known
> successful operation.

Can you try adding fragicmp=no? Or change /proc/sys/net/ipv4/ip_no_pmtu_disc to 1?

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