hi... I instaled debian sarge's base system with 5 interface that connects to 5 port on switch cisco 2950T that configured sprate VLAN. I use Iptables for inter vlan routing and firewalling, but i have problem and my frames have CheckSum error On tcp Header. why???????? required any patches??? Thanks Alot for attentions my switch config example) interface gig 0/1: switchport mode trunk ***** interface fast 0/10 switchport mode access switchport access vlan 3