TCPdump Tool

Overview

The TCPdump tool can be used to identify networking-related issues. This packet analyzer captures the actual packets sent and received by the vmpro appliance.

Refer to the Additional Resources section for more information about the TCPdump tool.

To collect TCPdump information during communications, run the following commands:

Create a file in temp to send dump output to.

bash-4.1# touch /var/tmp/tcp_capture

Determine what ethernet port troubleshooting concerns using the ifconfig command.

            bash-4.1# ifconfig
eth0      Link encap:Ethernet HWaddr 00:0C:29:0F:DE:DA
          inet addr:10.20.230.151 Bcast:10.20.231.255 Mask:255.255.248.0
          inet6 addr: fe80::20c:29ff:fe0f:deda/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
          RX packets:567282 errors:0 dropped:0 overruns:0 frame:0
          TX packets:382661 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:258956236 (246.9 MiB) TX bytes:112092397 (106.8 MiB)

lo        Link encap:Local Loopback
          inet addr:127.0.0.1 Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING MTU:16436 Metric:1
          RX packets:1821560 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1821560 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:296046060 (282.3 MiB) TX bytes:296046060 (282.3 MiB)

To trace the traffic between the vmPRO appliance and the NAS target, use the following command:

bash-4.1# tcpdump -i eth0 host 10.20.230.75 > /var/tmp/tcp_capture (10.20.230.75 being the NAS)

To dump the traffic while it ocurres on the vmpro appliance, use tcpdump -i eth0 > /var/tmp/tcp_capture
Collect the tmp files. In this case, the file is lcoated in /var/tmp/tcp_capture.
Use Wireshark to read the files. An example of how the bond#capture files display in Wireshark is shown below. To better understand wireshark, read the users guide (http://www.wireshark.org/download/docs/user-guide-a4.pdf). Make sure you have the latest version of the user's guide when troublehsooting.

Additional Resources

What's Next?

NetPerf Tool >