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I am using RedHat (6.5) bonding and my active interface is eth5.

Running the following command, I'm not able to see the traffic originated by my NIC IP address:

tcpdump -i eth5 src host actual_ip_address_of_external_client

I'm only able to see the source traffic too, via the command below (using wireshark):

tcpdump -i eth5 src host actual_ip_address_of_external_client -w /tmp/<outputfile>

What might be the problem?

  • Not 100% but I believe tcpdump supports the or operator – Bratchley Mar 31 '15 at 19:04
  • The question in this post includes an example of using the or operator. – Bratchley Mar 31 '15 at 19:04
  • thanks could you please me sample syntax regarding my situation ? or what else do you recommended instead of tcpdump command? please clarify – Selahattin Mar 31 '15 at 19:24
  • you should probably do something like tcpdump -i eth5 host <currentHost> or host <destinationHost> Just as an example: tcpdump -i eth5 host 192.168.122.23 or 192.168.122.25. – Bratchley Mar 31 '15 at 19:35
  • So are you saying that, without -w /tmp/<outputfile>, tcpdump doesn't print traffic from the actual_ip_address_of_external_client, but if you add -w /tmp/<outputfile> to the command, making no change to the filter or the -i argument, and then read the file in Wireshark, you do see traffic from that address? – user44841 Apr 1 '15 at 2:47
5

To monitor traffic on both directions between host_a and host_b you can use:

# tcpdump -nli eth6 host host_a and host_b
  • thanks info I solved my issue e.g tcpdump -ni s0 vlan and host_a and host_b and tcp 80 – Selahattin Apr 4 '15 at 12:32

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