Tcpdump support with onload library

Question

How can we enable dumping the packet data in tcpdump when our application run with onload library?

When the application run without onload library tcpdump captures the packet data but when we tried to run the application with onload library support, tcpdump not capturing any packet information

Answer 1

The tcpdump application captures traffic flowing through the Linux kernel so will not see traffic that bypasses this, as is the case when using Onload acceleration. For this reason Onload is bundled with an application called onload_tcpdump that intercepts traffic flowing through an Onload stack.

The captured traffic can either be from all Onload stacks or a specific stack. The usage information gives information on how to use it but the parameters are broadly identical to tcpdump, such as outputting to a file.

Information on using 'onload_tcpdump' is available in the Onload User Guide: https://docs.xilinx.com/r/en-US/ug1586-onload-user/onload_tcpdump