Troubleshooting Denial of Service
I have a Centos 4.4 server that is a standard LAMP server and as of recently I have had the server deny all services in the mornings but not every morning consistently. When I look at the physical server, the nic card light does blink but no so much that it is out of the ordinary, the hard disk activity light blinks too but is not solid or excessive, the server seems to be up but it denies every incoming connection other than ping requests. No dns, web, or even SSH
I thought it must be a cron job hogging system resources so I analyzed the cron log and the cron tasks seem to be running properyl even when the server is non responsive to inbound services. I ran every scheduled cron job and non of them bring the server down.
I have looked at the server logs but there is too much info to figure out what could be the problem and what couldn't. Is there a specific type of logging that I need to set or other method that I can use to see what is bringing my server down at night?
BTW, a simple hard reboot solves the problem until the next night/morning.
Your help is appreciated.