Kernel 2.2-17-14 RedHat

Please advise:

I can make a connection with my VPN client but no traffic is send back to my client. A ping to an address in the office resolves the address from the DNS server (in the office) but the reply is blocked by my server". (that's what it looks like?)

ping corpserver.mycompany.com
Pinging corpserver.mycompany.com [137.2.80.87] with 32 bytes..
Request time out.

I'm using a Novell VPN client that uses IPSEC (No PPTP)
VPN software uses port 353 UDP/TCP. (both are open)

It also requires to open:
IP protocol ID 57

How can I open "Protocol ID 57" with the ipchains commands?
My firewall uses the ipchains command set.

Thanks for your help,

Arie

PS: ipmasq and ipsec are installed