[OpenAFS-devel] 1.8.11pre1 client hanging on Linux 6.7

[Michael Laß]

Am Donnerstag, dem 25.01.2024 um 08:12 -0700 schrieb Cheyenne Wills:
> Can you run a packet capture from within the client itself?
> 
> We've seen an occasional client problem when the traffic was going
> through a vpn / firewall, and some of the udp packets were getting
> truncated.

That was a good hunch!

While capturing the RX network traffic with Wireshark, I experimented
with setting different MTUs on my network device:

* By default it's 1500. When set like that, I did not see any packets
containing directory listings coming from the file server.

* Reducing the MTU to 1280 made additional packets show up. In
particular, some would contain parts of directory listing. However, the
client would still hang.

* Starting afsd with -rxmaxmtu 1400 and leaving the network interface
MTU at 1500 fixes my issues with public cells (tested with desy.de and
kth.se).

However, trying to access the test cell in my own network still hangs.
I tried adding the rxmaxmtu argument to the bosserver of my test cell
but it did not help. 

It's still unclear to me why all of this is triggered by going from
Linux 6.6 to 6.7. Tomorrow I will try to create clean network captures
of both versions which will allow direct comparison.