Tcpdump data collection

Subba Rao castellan2004-nsm at
Wed Dec 3 01:19:50 UTC 2008


I want to collect data on a network and map the data flow and system/port traffic. There are 2 scenarios of data collection here.  The first is to collect IP traffic only.  In this method I do not want the data portion of the IP packet (need IP address, source/destination ports etc).

The second is to collect traffic that will show all the routing protocols (non-IP) used on this network.  Today while collecting the data, I saw several HSRP packets.  I don't know what portion of the packet is sufficient to capture for this purpose.

I used the "-s 0" option on tcpdump which captures the whole packet.  That is making the dump file large.  Any help with the filters is appreciated to capture the non-data portion of the packets.

Thank you in advance.

Subba Rao

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