Re: [PATCH net-next v5 00/10] Decouple receive and transmit enablement in team driver

Jakub Kicinski
2026-04-08T01:17:09Z

On Tue, 7 Apr 2026 16:06:02 -0700 Marc Harvey wrote:
> Thank you very much to kuniyu@google.com, who figured out how to
> recreate the issue on Fedora. Fedora's /etc/services maps TCP port
> 1234 to the "search-agent" service (normal), which tcpdump then uses
> to text-replace port numbers in its output. So the tests were looking
> for ${ip_address}.1234, but tcpdump was spitting out
> ${ip_address}.search_agent. What is strange is that the test already
> uses tcpdump's "-n" option: "Don't convert addresses (i.e., host
> addresses, port numbers, etc.) to names."
>
> It turns out that Fedora has a patched version of tcpdump that
> separates the normal "-n" option into two options! "-n" handles host
> addresses, and "-nn" handles port and protocol numbers. The tcpdump
> invocation used by the selftests only uses "-n". What's stranger is
> that passing "-nn" to tcpdump is actually portable, because under the
> hood it is treated as a counter, with or without the Fedora patch:
> https://github.com/the-tcpdump-group/tcpdump/blob/master/tcpdump.c#L1915
> (thanks again to Kuniyuki for discovering this).

Oh wow! Thanks to both of you for not giving up and getting to the
bottom of this :)