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Re: ssh connection survives reboot of stateful iptables router

On Tue, 4 Jul 2006, martin f krafft wrote:

> also sprach Jozsef Kadlecsik <kadlec@blackhole.kfki.hu> [2006.07.04.1143 +0200]:
> > That is false, because from connection tracking point of view a plain ACK
> > packet which does not belong to any existing connections has got a state,
> > which is NEW. That is why connection pickup can work.
> Yeah, and so it's not INVALID. I did not know about connection
> tracking, but other than that, the following two are equivalent, no?
>   drop INVALID
>   accept --dport 22
>   drop
> and
>   accept --dport 22 --syn
>   drop

No. In the first case you drop INVALID packets (actually, broken ones:
invalid flag-combinations, bad checksum, etc.) and accept any packet
targetting port 22. In the second case you accept SYN packets sent to port

Best regards,
E-mail  : kadlec@blackhole.kfki.hu, kadlec@sunserv.kfki.hu
PGP key : http://www.kfki.hu/~kadlec/pgp_public_key.txt
Address : KFKI Research Institute for Particle and Nuclear Physics
          H-1525 Budapest 114, POB. 49, Hungary

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