Tcpdump raw output but grepping aswell

synick · 07-23-2008, 07:31 PM

Hi Guys,

I have had a hunt around the interweb to see if I can perform a tcpdump on an interface, grep based on certain ip's but also writing it as raw output:

Something like:

tcpdump -i eth0 -w tcpdump.cap | grep 10.0.0.1 | grep 10.0.0.2

But that doesn't work, I have also had a look through the man page and can't seem to spot any commands to grep with a -w.

Any help is greatly appreciated.

Regards.

chrism01 · 07-23-2008, 11:01 PM

You need the tee cmd : http://www.ss64.com/bash/tee.html

/usr/sbin/tcpdump -i eth0 | tee tcpd.dmp |grep blah

estabroo · 07-23-2008, 11:46 PM

If you only want to capture packets for those hosts

tcpdump -i eth0 -w tcpdump.cap host 10.0.0.1 or host 10.0.0.2

That'll capture packets whose source or destination is either of those hosts.