I've noticed this for a while and wanted to see what this was. For a while now, probably a couple of months this particular message has been appearing my "messages" log file.

May 18 04:40:02 mybox syslogd 1.4.1: restart.
May 20 20:01:53 mybox -- MARK --
May 20 20:21:53 mybox -- MARK --
May 20 20:41:53 mybox -- MARK --
May 20 21:01:53 mybox -- MARK --
May 20 21:21:53 mybox -- MARK --
May 20 21:41:53 mybox -- MARK --
May 20 22:01:53 mybox -- MARK --


The MARK is what confuses me. It happens literally every twenty minutes. I thought it could be related to something with iptables, because I vaguely remember that being a target in iptables.

Thanks in advance.

why dont you use 'iptables - L' and check if it really is specified in the iptables rules and see if logging is enabled for that rule

Restarting syslogd with "-m 0" should work AFAIK.

I think unSpawn is right but it is there for a reason.

The syslog daemon can be set to write a "MARK" into the file if no other messages have been written. It can be useful for finding out when a system has crashed/stopped responding.

You would think that the fact that this occurs every 20 minutes and is called "Mark", it could maybe mean something? .... or, maybe not.
; )