I was reading my linux security Cookbook today and i came apon a good way to prevent DOS attacks in linux.



QUOTE
For xinitd, use the cps,instances,max_load and per_source keyworks

CODE
/etc/xinetd.conf or /etc/xinetd.d/myservice


CODE
service myservice

{

  ....

  cps = 10 30

# Limit to 10 connections per secont if the limit is exceeded sleep for 30  #seconds.



  instances = 4

#limit to 4 concurrent instances of myservice

 per_source = 2

#limit 2 simultaneous sessions per source ip address Specify UNLIMITED for no #limit, the default

   max_load = 3.0

#Rejects new request if the on-minite system load average exceds 3.0



}


I highly recommend editing this to what you feel safe with for your server.