Almost like clockwork, my server crashes on or near the first of the month for the last 6 months. The only way to get it back online is a hard reboot followed by a 2-hour file scan.

I suspected a software update that keeps freezing, but I haven't been able to find it. Worse, all I can do is try to set up a monitor and wait until next month to see if it freezes!

My server is semi-managed, and their sysadmin said this:

You have a iptables rule that prevents it from restarting. We don't know which one but unless we flush them it doesn't come back.

I asked for clarification, but so far haven't had a reply. That "unless" confused me; did they mean that "unless we flush them it will come back"? Or, "if we don't flush them then it won't come back"?

I used iptables -S to list all of the rules, and there are only about 20 of them with the first one dated yesterday. If they expire after a day or two then that wouldn't explain why this is happening every 4 weeks! Unless the sysadmin flushed them and didn't tell me?

Any suggestions on how to track this down? I know practically nothing about iptables and don't understand their purpose or how they work, so at this point I'm just plugging in commands I'm finding online and seeing what happens.