Re: sent an invalid ICMP type 11, code 0 error to a broadcast: 0.0.0.0 on lo?

["Richard B. Johnson" <linux-os@analogic.com>]

On Fri, 8 Jul 2005, Denis Vlasenko wrote:

> > The problem is, I can't see what is causing this misconfiguration
> > or whatever.  I wasn't able to capture such a packet so far either --
> > it never happened while tcpdump was running.
>
> You may try to add printk("bad boy is: %s\n", current()->comm)),
> or dump_stack(), or something like that in icmp path of IP stack.
> (I am currently tracking an intermittent network problem
> on my home box in similar way).
>
> >  Note the local IP address mentioned is different, I've
> > seen 3 so far, all 3 are local on this box and are on 3
> > different (ethernet) interfaces (but the ICMP always comes
> > from lo).
>
> BTW what tcpdump actually shows?
> --
> vda

Please read line 1148 of /usr/src/linux-`uname -r`/net/ipv4/icmp.c.
The error message is in response to a bogus frame. The NETMASK
must match at both ends (a configuration error). If the mask matches,
then you can turn off the messages with 'sysctl', i.e., ....
`echo "1" >/proc/sys/net/icmp_ignore_bogus_error_responses`.
Otherwise, find the interface netmask that's broken and fix it.

Cheers,
Dick Johnson
Penguin : Linux version 2.6.12 on an i686 machine (5537.79 BogoMips).
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