Postings by Laszlo Danielisz

bad udp cksum


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.