LinuxQuestions.org - [SOLVED] Empty lines in output of tcpdump

- Linux - Networking (https://www.linuxquestions.org/questions/linux-networking-3/)

- - Empty lines in output of tcpdump (https://www.linuxquestions.org/questions/linux-networking-3/empty-lines-in-output-of-tcpdump-945519/)

Empty lines in output of tcpdump

I can see strange output of tcpdump. Occasionally I use the tcpdump to monitor the network traffic. I am on the public net and connecting to the server with ssh so my command is:

Code:

tcpdump not port 22 and not multicast

The network has a huge multicast traffic so I filter this out and the ssh too.
The output contains cca. 5-10% of empty lines. The line contains only the date and time and nothing more. What can cause this?
This is the sample of the empty lines:

Code:

15:18:10.195434

15:18:20.195831

15:18:30.196248

15:18:40.196659

See the mac of the sending machine by adding -e to your command line.
I believe they are cisco loopback packets - see https://supportforums.cisco.com/thread/5466

Quote:

Originally Posted by nikmit (Post 4680888)

See the mac of the sending machine by adding -e to your command line.
I believe they are cisco loopback packets - see https://supportforums.cisco.com/thread/5466

Thank you it works and those packets are exactly as you told.