Cisco VPN Client

Hi,

I am trying to connect to the cisco VPN server from my network which
has linux firewall and windows 2000 systems. I have installed the Cisco
VPN Client on one of the windows 2000 pro system and trying to connect
and I am not able to connect with the error "Secure VPN Connection
terminated localy by the client Reason 412: The remote peer is no
longer responding"

When i went through some document in the net they say that

UDP port 500
UDP port 10000 (or any other port number being used for IPSec/UDP)
IP protocol 50 (ESP)
TCP port configured for IPSec/TCP
NAT-T port 4500

Should be open

I am not soo good at IPtables. Can any one tell me how to open this
ports in the iptables so that i can dial my vpn client

Plzz some one help me on this issue

Regards

Vinod