Allow single computer access into secure network

[lfields]

Hello

Not getting any help over on the Mandriva forums....

I have a gateway server running Mandriva 2010.1. It sits between 2 networks, aaa.aaa.aaa.aaa is a main company network, and bbb.bbb.bbb.bbb is a separate secure network. The Mandriva box is the only physical connection between the two networks. This computer is running squid/dansguardian for internet access to bbb. Other than that, there is no traffic between the two.

I need to allow 1 computer on the aaa network access through mandriva box into bbb network. No other traffic of connections to the aaa network except the 1 computer. What would be my best option for this? Ip Forwarding, Routing, IPTables, VPN? And which one would be the most practical to setup?

I have been playing with gadmin vpn, and open vpn. Something in the configuration kills my bbb (lan) network when vpn is started. Maybe vpn isn't the best approach? Any suggestions?

Thanks for any help.

[lfields]

How about some shorewall rules that allow a single ip address on eth0 access in and out to eth1?

[linuxero]

I guess there are some important parts missing in the question! Sorry if I can't get you well..