Services Going Offline nf_conntrack table fulll

For the last 2 nights my servers has shown services as being offline and the system log is full of the following:-

nf_conntrack: table full, dropping packet



Now I understand this may be a DOS or DDOS attack on the server.

A reboot cures the problem but I can't reboot the server every night as that's impracticable.

I should add that although the services are showing as offline - they are in fact online. i.e. the www service is showing as offline but all my sites are up.



Any help in curing this would be appreciated. This never happened before the upgrade to 3.0.5.4 and 3.0.5.4p1

Many thanks

Jeff

 

UPDATE:

It looks like my server is being attacked nightly by some kind of stress attack. Here are the list of connections:-



So it does look like some kind of dos attack and putting the system under loads of stress.

Any recommendations for counter defence ?

Jeff

 

Please don't double-post.
http://www.howtoforge.com/forums/showthread.php?t=65970

 

Apologies, I thought the priority support threads were hidden so posted in the general support as well.

Lesson learned.

Jeff