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conntrack-0.9.6 bug (?)

DISCUSSION Pablo Neira Ayuso 1 participant 1 message Apr 16, 2008 3 messages not in the archive

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Quoted 22 lines · Stefan Behte

I managed to get the connection deleted before with:
conntrack -D -s 212.202.252.50 -d 192.168.40.88 -p tcp --sport 23854 --dport 22

It did not show up in conntrack -L -s 212.202.252.50 anymore, but was still in "ESTABLISHED" state, the packets kept flowing.

So thought, that might be an error?!

Also, this does not work:

[root@haq ~]# conntrack -L | grep "dport=22 "
tcp 6 431999 ESTABLISHED src=192.168.0.2 dst=192.168.0.1 sport=22
dport=33555 packets=11 bytes=1324 src=192.168.0.1 dst=192.168.0.2 sport=33555 dport=22 packets=18 bytes=1272 [ASSURED] mark=0 use=1 [root@haq ~]# conntrack -D -s 192.168.0.2 -d 192.168.0.1 -p tcp --sport 22 --dport 33555
[root@haq ~]# conntrack -L | grep "dport=22 "
tcp 6 431999 ESTABLISHED src=192.168.0.2 dst=192.168.0.1 sport=22
dport=33555 packets=5 bytes=628 src=192.168.0.1 dst=192.168.0.2 sport=33555 dport=22 packets=8 bytes=560 [ASSURED] mark=0 use=1

Quoted 4 lines

Or am I doing it all wrong?!
If that is really a bug, where would be the appropriate place to file a bug report so that I do not have to bug you directly via mail (which might be regarded as inappropriate)?

Probably your stateful rule-set is not well-formed or you have the connection pickup facility enabled (/proc/sys/net/ipv4/netfilter/ip_conntrack_tcp_be_liberal must be 0, otherwise the connection tracking can recover connections from the middle with no complain). There's an example of a sane and simple stateful ruleset in [1].

Don't forget that the connection tracking system does not drop packets by itself, you need a correct iptables configuration to enable the flow deletion, otherwise it won't work.

[1] http://conntrack-tools.netfilter.org/testcase.html

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