26 Feb
2021
26 Feb
'21
5:01 p.m.
On 26.02.21 12:29, Silvan M. Gebhardt wrote:
Isn't that the case with tcp_offload enabled in the NIC that tcpdump will see incorrect checksums?
I'm by no means a tcpdump expert:
Those incorrect checksums: are my systems generating incorrect checksums or is it the swisscom side? It seems weird that different systems with different OS at different customers would all start making wrong tcp checksums.
Checksum errors are rather common to originate in virtualization platforms. It is one of the things to check for when deploying new infrastructure. Even some bigger resellers hand out VMs with these problems: I occasionally have to add a "ethtool -K $IFACE rx off tx off" command to the boot process.
Cheers Claudio