Re: VPN Connection Failure

Tech-Archive recommends: Repair Windows Errors & Optimize Windows Performance

From: Marina Roos [SBS-MVP] (marina_at_roos.nodontwantspam.nl.com)
Date: 02/19/05 

Date: Sat, 19 Feb 2005 15:30:25 +0100

Hi Jim,

Error 721 means that your router is not passing through the GRE-protocol 47,
also known as PPTP Pass through. Your router might need a firmware upgrade,
or maybe even a downgrade. 

-- 
Regards,
Marina
Microsoft SBS-MVP
One of the Magical M&M's
"Jim" <Jim@discussions.microsoft.com> schreef in bericht
news:DB1831AB-7C0E-4555-B618-C516209A284A@microsoft.com...
>
>
> "Joe" wrote:
>
> > In message <70EFA3DA-E7F8-410A-A6E2-D92189A97A60@microsoft.com>, Jim
> > <Jim@discussions.microsoft.com> writes
> > >I am having difficulty resolving a VPN connection error.  When
attempting to
> > >establish a VPN connection, the client shows that it has contacted the
server
> > >and is attempting to authenticate the user ID and password (PPP).
> > >
> > >It eventually times out and fails/retrys in a continuous loop.
> > >
> > >From the server, I can watch the connections as see that the VPN
connector
> > >in question is active.  It starts with a state of "listening" and then
> > >changes, showing an attempted connection.
> > >
> > >I have tried to enable logging (errors) but don't see anything.  The
user
> > >profiles have dial-in access enabled and are members of the "mobile"
group.
> > >
> > >When the client is in my local domain, it connects without any problem.
> > >This issue only occurs outside the firewall.  I know what you are
thinking -
> > >the firewall is the issue, but this still occurs when I turn the
firewall
> > >off.  I have the ports indicated in the documentation turned on and
forwarded
> > >to the server's IP and, to ensure this, I have also enabled PnP
> > >configureation of the firewall by the SBS internet connection wizard.
It's
> > >not the firewall (unless there is something way down in the weeds that
I
> > >missed).
> > >
> > Quick shot in the dark: does the client have a network interface set to
> > use the same IP subnet as the SBS LAN? If so, routing won't work so
> > nothing gets sent up the link. Call up the connection status display as
> > soon as possible after the link comes up and look at the IP addresses.
> > Compare with 'ipconfig /all' on the client.
>
> the subnet mask is 255.255.255.0 for all computers involved.
Additionally,
> the configuration wizard for remote access in SBS defaults to using a
server
> assigned, dynamic IP address for the client using RAS.  Would this type of
an
> error be a minconfiguration in how the dynamic address is assigned?
>
> >
> > The other classic cause of 'connection made, no authentication' is that
> > the TCP/IP connection over port 1723 is working, but not the GRE
> > protocol 47 connection. PPTP only needs the first to make a connection,
> > but needs the second to actually pass data, including authentication
> > negotiations.
> >
> Both ports are enabled and forwarded through the firewall to the IP
address
> of my SBS.
>
> > >This issue only occurs outside the firewall.  I know what you are
thinking -
> > >the firewall is the issue,
> >
> > Apart from IP routing issues, this *is* a rational conclusion. Apart
> > from the firewall's behaviour, you're on a different IP subnet than when
> > connected locally. It seems very likely that one of the two factors is
> > to blame. When you say 'turn the firewall off' are you sure it's passing
> > everything?
> >
> It is a linksys firewall/router and I have tried setting the firewall to
> "off" and I receive the same result.  Also, the firewall settings on the
LAN
> and WAN adapters within the SBS server are off.
>
> > >Any ideas or recomended approaches to resolve this issue?
> > >
> > The firewall is usually the best line of attack, even if it isn't likely
> > to be the cause of the problem. Does it keep a log of connections, and
> > can you deduce anything from that? A firewall or router which can be
> > configured to log particular port traffic or protocols while passing
> > them is extremely useful in this situation.
>
> I will try logging at the firewall, thanks for the idea.  BTW, the error I
> receive at the client is a "721" error:  the remote computer did not
respond
> to the connection request.
>
>
>
> > -- 
> > Joe
> >

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