When is a connection ESTABLISHED in ip_conntrack?

When is a connection ESTABLISHED in ip_conntrack?

[James Garrison]

Partial listing of ip_conntrack:

> tcp      6 296619 ESTABLISHED src=10.56.8.1 dst=10.56.8.218 sport=39594 dport=80 packets=1 bytes=40 [UNREPLIED] src=10.56.8.218 dst=10.56.8.1 sport=80 dport=39594 packets=0 bytes=0 mark=0 use=1

> tcp      6 296616 ESTABLISHED src=10.56.8.1 dst=10.56.8.183 sport=39594 dport=80 packets=1 bytes=40 [UNREPLIED] src=10.56.8.183 dst=10.56.8.1 sport=80 dport=39594 packets=0 bytes=0 mark=0 use=1

> tcp      6 296616 ESTABLISHED src=10.56.8.1 dst=10.56.8.179 sport=39594 dport=80 packets=1 bytes=40 [UNREPLIED] src=10.56.8.179 dst=10.56.8.1 sport=80 dport=39594 packets=0 bytes=0 mark=0 use=1

These are left over from a portscan I ran 2 days ago, and there's an
entry in ip_conntrack for each and every unused IP address on our
internal subnet.  Why is the connection status 'ESTABLISHED' if
there was never a response to the original SYN?  This causes
ip_conntrack to use the 5-day timeout instead of 2 minutes and
clutters up the table.

This isn't really a problem, I'm asking out of curiosity and to
better understand connection tracking.

-- 
James Garrison                                Athens Group, Inc.
mailto:jhg@athensgroup.com                    5608 Parkcrest Dr
http://www.athensgroup.com                    Austin, TX 78731
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