SYN flooding

[Erdal MUTLU]

Hello,

Last Friday I installed a RedHat 7.2 with ext3 file system, custom 2.4.18 
firewall and ipytables-1.2.5. The server is a squid cache. When I try to use 
it as a HTTP proxy I get a lot of SYN flood in my log file.

$ipt --new-chain syn-flood
$ipt --append syn-flood --match limit --limit 1/s --limit-burst 4 --jump 
RETURN
$ipt --append syn-flood --jump LOG --log-prefix "$fw SYNFLOOD:"
$ipt --append syn-flood --jump DROP


......


$ipt --append INPUT -i eth0 --protocol tcp --syn --jump syn-flood 
$ipt --append INPUT -ieth0 --protocol tcp --syn --jump syn-flood 


I have RedHat 7.1 with ext2 with 3 interface cards and with the same rule and 
works perfect.

I changed Inter pro100 NIC to  3c905C-TX without success.

What can be the cause of the problem?

Best regards.
Erdal MUTLU