How to find source of problem?

Im curious as to how to track down who is responsible for increasing loads on a server? I have attached the nodeworx monitoring png, please look just before midnight there was sharp increase in usage then all shuts down and restarts - thanks to SIM.

I looked at individual usage stats for each site since I only have 10 sites on there currently. None of them have any sharp peaks that match the png I uploaded here. This has only happened once before a couple of weeks ago, causes loads to go through the roof rendering the server inaccessible. Could it be interworx? How can I investigate further to find the source of the problem?

Thanks!

monitoring.png

Nov 17 21:20:01 secure04 kernel: ** SSH ** IN=eth0 OUT= MAC=00:11:09:26:39:02:00:02:fc:0c:b4:00:08:00 SRC=66.232.152.6 DST=8.6.221.92 LEN=60 TOS=0x04 PREC=
0x00 TTL=63 ID=21957 DF PROTO=TCP SPT=48372 DPT=22 WINDOW=5840 RES=0x00 SYN URGP=0

Got a lot of the above before SIM restarted services in the message log. Not sure what it means, if its any significance.

Nevermind,

Delete this thread. I seem to have overlooked a site. I found the problem.

Thanks!

And what was the pbm ?

Im guessing a memory leak and ran out of memory. Hard to say. Need better system accounting tools.