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Problems with IPSEC VPN clients and certain routers

Our internet/network setup uses a Speedstream 4200 adsl2 modem running in bridged mode, with a netscreen 5GT firewall handling the pppoe authentication and all other routing/firewall policies etc.. Some client pc's inside the LAN use Cisco VPN client with transparent tunneling and IPSEC over UDP to connect to some remote sites. Recently I had to replace the speedstream and I purchased a Netcomm NB6plus4. To my disappointment the cisco VPN connections no longer work. The client authenticates but no network resources are available. I assume the problem is the fact that the netcomm does not support IPSEC tunneling.

What I would like to know is what to look for in a modem which will have the required functionality. I see some refer to "IPSEC passthrough", is that sufficient for my purposes?

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I tend to find it easier by getting a VPN router that also has a DSL modem built in rather than having a DSL modem in bridge mode passing stuff through to the router, cos as you have found out, some modems don't support all the required pass through.

As you already have a NS5GT I would consider moving to the latest juniper offering with ADSL PIM support, this is the SSG 20


Or alternatively, have a word with your Juniper and cisco support company to get a listing of the approved DSL modems that will support all your VPN needs.

Sanga CollinsSystems AdminCommented:
Is your new modem also in bridge mode?
computron-australiaAuthor Commented:
Yes, new modem is in bridged mode. I agree that the combined ADSL firewall would be a better option but at the time of purchase we were not using ADSL internet service. Given the cost involved of replacement I would prefer to find a simple router which works in bridge mode and allows the ipsec tunneling. I think something like the D-Link 504T mayfit the bill but I was really just seeking clarification that the "IPSEC passthrough" functionality is really the feature I need to look for.
computron-australiaAuthor Commented:
o.k I have done a bit more research on this myself. When the router is operating in bridged mode, it should basically just operate as a dumb modem, meaning that things like ipsec passthrough are irrelevant because all traffic should pass through and be handled by the netscreen firewall. I discovered that the reason the ipsec vpn clients were having problems was because the management IP address of netcomm router was on the same subnet as one of the 2 IP addresses assigned to the PC which I was using to test the VPN. By removing this 2nd IP the VPN clients now work successfuly.
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