Sending UDP/514 data magically appears in syslog without rsyslog running
- by ale
I’m using a programming language without a library to log to rsyslog over UDP. I thought I was going to need to write a library but I discovered something weird.
If I send data on UDP/514 with the port open on the server then the data appears in the server’s syslog. rsyslogd isn’t running so syslog isn’t doing this. Data doesn’t get formatted into a syslog message so rsyslogd really isn’t doing this (only raw text enters syslog). Linux must see the data coming in on this port and know that it should go into /var/log/messages?
If I do the same on another port (e.g. UDP/515) then nothing appears in the log!
What is doing this? Some CentOS feature? The kernel?