[pptp-server] Linux NAT support PPTP packet editor/filter?

[Chuck Flink]

Example:  PCa--homeLAN--PCb--RoadRunner--Internet

PCb is gateway running Win2K Router with NAT routing rules.
PCa is client PC accessing Internet through gateway.
PCa can dial to remote work LAN/WAN via PPTP thru PCb,
totally transparently.  (Neat!)  E.g.:

PCa--PPTP(--homeLAN--PCb--RoadRunner--Internet)--Work

Desired:  Linux configuration on PCb with similar functionality.

I'm experimenting with Win2K Server as a NAT/PPTP gateway.... 
Win2K Server RC2 includes Router services with NAT routing
rules including support for a PPTP "packet editor/filter" (Microsoft
 terminology?) that supports editing PPTP packets so they pass
thru the NAT gateway. (Note: using NAT routing option under the 
Router service in Windows 2000 Server, NOT the similar but less
functional NAT called the Internet Connection Service (ICS) also 
available under Win2000 Professional as well as the Server.)  

I don't want to pay for W2K Server when it is released next year.
My use is very 'non-profit', or at least certainly not profitable!  :-)

Cost considerations lead me to Linux (preferred) or the Win2K
Professional version using ICS (which doesn't seem to integrate 
as well with PPTP, nor does it offer the same security features 
as the Router service on the Server configuration.)

Does the PPTP support for Linux integrate with Linux NAT 
such as to support the passing of PPTP sessions through NAT, 
analogous to what I am now doing with the Win2K RC2 beta?

I believe IPsec / L2TP cannot be filtered / edited to pass through
NAT gateways like PPTP can.... correct me if I'm wrong.  I'd
prefer to use the more open IPsec standard if it could be made
to be as transparent as PPTP.

Thanks!

-Chuck Flink  cwf at att.net
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