bad udp cksum messages in tcpdump for wg0

Matthias Urlichs matthias at
Fri Dec 27 15:45:04 CET 2019

> ethtool -K wg0 tx off rx off
> I want to know if the behavior described above with the checksum
> errors is to be expected? Or is it necessary to turn those checks off
> on all the interfaces?

Yeah. I need that too, on one of my routers. Apparently some checksum
offloading hardware gets confused by wireguard.

Interestingly, on that machine fixing this problem requires turning off
checksumming on the wg interface _or_ on the hardware interface, either
way is sufficient.

-- Matthias Urlichs

More information about the WireGuard mailing list