Re: [LARTC] Routing problem (RTNETLINK answers: Invalid argument) on

[Paul Viney <paul@diasoft.nl>]

> > I still seem to have much the same problem. I no longer get ICMP
> > unreachable errors, but the packet just seems to disappear - I can't see
> > it being forwarded on any interface, nor can I find any kind of reply -
> > icmp or otherwise.
>
> sounds like a firewall issue!

It does sound like a firewall issue, but the only firewall rule I have at the 
moment is the one doing the DNAT. If I do 'iptables -t nat -L -v', then I can 
see the number of packets increasing. Once I remove the firewall rule, I get 
my "icmp unreachable" errors again. Funnily enough, if I then reinstate the 
firewall (dnat) rule, then I still get "icmp unreachable" errors and the 
packet count doesn't go up for the rule. It's almost as though the rule 
doesn't get consulted. 'ip route flush cache' doesn't make a difference. 
After about 5 minutes the "icmp unreachable" errors stop and the packet count 
starts going up, although I still can't find my packet on the next hop. (I do 
have forwarding switched on). The packet count on a iptables log rule on the 
forward table does not go up, giving me the impression that routing has 
failed. 
I also tried ip r get <random internet address> from 192.168.12.5, which did 
indeed give me the same "RTNETLINK answers: Invalid argument" error. I guess 
that means that my understanding of the purpose of 'ip r get' is indeed 
faulty. 

Thanks for all your help so far.

Paul Viney

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