-----Original Message-----
From: Bonmariage, Serge [mailto:serge.bonmariage@GETRONICS.com]
Sent: 22 April 2005 14:45
To: security-basics@securityfocus.com
Subject: how to trace what is accessing the nic ?
Hi everyone,
There is happening something very strange on one of our Linux
SMTP gateway.
We've recently discovered that it is sending some strange TCP
packets to always the same private address.
[root@server1 root]# tcpdump -i eth0
tcpdump: listening on eth0
14:29:50.226313 server1.mysite.com.59806 > 192.168.234.236.5860: S
312929991:312929991(0) win 5840 <mss 1460,sackOK,timestamp
1658853393 0,nop,wscale 0> (DF) 14:29:53.222040
server1.mysite.com.59806 > 192.168.234.236.5860: S
312929991:312929991(0) win 5840 <mss 1460,sackOK,timestamp
1658853693 0,nop,wscale 0> (DF)
14:29:59.222028 server1.mysite.com.59806 > 192.168.234.236.5860: S
312929991:312929991(0) win 5840 <mss 1460,sackOK,timestamp
1658854293 0,nop,wscale 0> (DF)
However we don't detect any other abnormal acvtivity.
The question is quite basic but is there a way to trace which
process is trying to send these packets?
If you can catch the process in the middle of it sending some packets,
try running
netstat --inet -nap
as root. I think this gives you a list of all processes with network
sockets open, together with the process id and name.
Simon
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