Security Incidents mailing list archives

Re: Odd traffic again...... internal --> 100.100.100.1 (137-udp)


From: Tillmann Werner <tillmann.werner () gmx de>
Date: Thu, 24 Aug 2006 19:07:10 +0200

eth1c0:o[78]: 192.168.x.x -> 100.100.100.1 (UDP) len=78 id=13167
UDP: 137 -> 137
eth1c0:O[78]: 68.163.87.34 -> 100.100.100.1 (UDP) len=78 id=13167
UDP: 49902 -> 137

You have two different source ip addresses here. Are they on the same box? The 
source port differs, but at least the ip id is equal. Strange - a 
coincidence? Your ACL log even showes a third source port. Btw, I think there 
is no need for camouflaging rfc1918 addresses...

I am now capturing the traffic again, though there is nothing in it.

For a packet size of 78 you have up to 50 bytes of payload (depending on the 
presence of ip options). So what means 'nothing in it'? A full packet 
capture, for instance tcpdump's hex output, would help. Maybe in addition to 
creating a local alias with an address of 100.100.100.1 and netcatting the 
connection.

Tillmann

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