RE: [LARTC] Gre Tunneling Problem

From: Greg Scott <GregScott@InfraSupportEtc.com>
To: lartc@vger.kernel.org
Subject: RE: [LARTC] Gre Tunneling Problem
Date: Wed, 09 Jan 2002 17:49:08 +0000	[thread overview]
Message-ID: <marc-lartc-101059854819490@msgid-missing> (raw)
In-Reply-To: <marc-lartc-101039544916808@msgid-missing>

I found lots of stuff in a bunch of Windows 2000 documentation and 
in abook about Windows 2000 VPNs by Thaddeus Fortenberry.  Ziegler's 
Linux Firewalls Second Edition barely mentions VPNs in a brief 
chapter in the back of his book.  

I stumbled across the HOWTO that had the sample VPN commands and my 
jaw dropped - I've been looking for that capability for months!  I
don't even remember where that HOWTO lives any more, but that's OK
because I copied it so I would always have it handy.  

What happens is, the two tunnel endpoints exchange some TCP port 1723
messages to handshake with eachother and then they have a conversation
using IP protocol 47, also named GRE.  So the whole thing, handshake
and authentication, is called PPTP.

What I don't understand is, how does the security work?  I think the 
two tunnel endpoints are supposed to authenticate eachother with the
TCP port 1723 packets, but what do the Linux systems use for a shared 
secret?  I would use this all over the place if I felt good about its
security.

- Greg

-----Original Message-----
From: Michael T. Babcock [mailto:mbabcock@fibrespeed.net]
Sent: Wednesday, January 09, 2002 8:28 AM
To: LARTC List
Subject: Re: [LARTC] Gre Tunneling Problem

That's something I haven't seen well mentioned elsewhere; like in the
Linux options for GRE tunneling.  Anyone know where else this association
should be mentioned?

On Tue, Jan 08, 2002 at 08:44:31PM -0600, Greg Scott wrote:
> Yes - they are both the same.  GRE is the name of the IP protocol used
> for exchanging messages.  PPTP - Point to Point Tunneling Protocol.
-- 
Michael T. Babcock
CTO, FibreSpeed Ltd.     (Hosting, Security, Consultation, Database, etc)
http://www.fibrespeed.net/~mbabcock/

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