Every other morning, My server comes under a massive attack from ICMP. I would like to know what steps I can take to prevent this from happening...

Thank You :D

Install a firewall and block ICMPs ;)

How will this affect my server?

depends what type of ICMP traffic flood you got..... if you block all icmp traffic.. then you will be not able to ping your box/server and traceroutes will reply with * for your server hop ;)

http://www.webhostingtalk.com/showthread.php?s=&threadid=40887

Install APF ... it has got a way to limit the amount of ICMP Replies :)

And i was going to remove the icmp rate limiting in APF; didnt think it served any use let alone if anyone could launch effective ICMP attacks anymore :P