Hi,
Recently I'm noticing an interesting issue. My CentOS servers are trying to send logs to a logging server via 514/udp, however I'm not receiving anything.
I did the following on CentOS *tcpdump -vvv -nn udp -i esn160 port 514*
In another session on the same server: *nc syslog-server -u 514*
tcpdump started to show me messages like: *[bad udp cksum 0x3ce9 -> 0xb0f5!] SYSLOG, length: 172*
After some research I disabled TCO (ethtool -K ens160 tx off rx off), now tcpdump shows: *[udp sum ok] [|syslog]* And I'm also receiving the logs. Yay!
I have the same issue on multiple servers with CentOS versions 7.3.1611, 7.4.1708 & 7.5.1804. I'm having the issue no matter if it is a physical or virtual server (they also use different hardware and NIC's)
Of course I could run ethtool every time a server starts but I think there should be a better solution. Also I enjoy having TCO giving some rest to the CPUs.
Did anyone find a solution for this?
Thanks! Laszlo