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On Tuesday 05 August 2003 15:01, Ollie Gallardo wrote:
> Hello,
> I was wondering if someone could point me to some documentation that
> clearly describes the setup for the following scenario or a very similar
> scenario.
>
> SoftRemote roadwarrior->NAT->Internet->FreeS/WAN gateway->Private Subnet
>
> The key for me here is that the road warrior is not linux and it's behind a
> NAT router.  I would like to have a FreeS/WAN gateway that that will allow
> connections from any roadwarrior (with the proper credentials) behind any
> NAT router or firewall that is allowing IPSec Passthrough.  I've gone
> through hours of searching and havn't found anything that clearly explains
> it or gives me a 1 2 3... on how to do it.  Any help would be appreciated.

Do you know what NAT-Traversal is? If not, here's a brief overview of the 
technology involved.

http://www.infoworld.com/article/02/02/15/020218nenat_1.html

So long as both IPsec devices are NAT-Traversal capable, they can bypass NAT 
without too much fuss. (They've also support the same drafts of *how* to do 
NAT-T...)

Mathieur Lafon has provided a NAT-Traversal patch for FreeS/WAN. This is 
included in SuperFreeS/WAN.

http://open-source.arkoon.net
http://www.freeswan.ca

The only catch is that your roadwarrior clients have to have NAT-Traversal 
capable clients. Microsoft recently made NAT-T patch available for the native 
win2k/winXP IPsec clients.

http://support.microsoft.com/?kbid=818043

Okay, but let's say that you can't rely on NAT-Traversal for your 
roadwarriors, but you've got IPsec passthrough enabled on the various 
NAT'ting routers. This is still possible.

http://lists.freeswan.org/pipermail/users/2002-August/013710.html
http://jixen.tripod.com

Simply speaking, the key is that the RW clients don't know their own, public 
IP address; they've got a non-routeble address, and will try to negotiate a 
tunnel using that private address. Basically, you've got to define 
Roadwarrior connections that allow for that IP address being "behind" the 
roadwarrior, eg:

conn roadwarrior
        ...
        right=%any
        rightsubnet=192.168.0.50/32  # Frank's IP address behind his NAT box


A pain, huh? You'd have to define individual connections for all your 
roadwarriors' private IP addresses, which can easily change. There's a way 
around this: you can use the "rightsubnetwithin" parameter provided by x.509 
patched FreeS/WAN.

http://www.strongsec.com/freeswan/install.htm#section_4.4

conn roadwarrior
        ...
        right=%any
        rightsubnetwithin=192.168.0.0/16

would allow your roadwarriors to connect when they have any non-routeable IP 
address in the 192.168 class B.

As an aside, NAT-Traversal allows you define "virtual_private" in config 
setup; you can define all the non-routeable networks there in a single line:

http://lists.freeswan.org/pipermail/users/2003-March/019234.html
http://open-source.arkoon.net/freeswan/README.NAT-Traversal.0.6

This should allow you to define all the non-routeable network ranges allowed 
conveniently. (I believe this should work with non-NAT-Traversal capable 
clients as well.)

- -- 
Sam Sgro
[EMAIL PROTECTED]

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