PPTP uses port 1723/tcp to establish communications. This apparently is
working, since you can get to the PPTP server and see some status messages.
PPTP then uses protocol 47 -- GRE, generic routing encapsulation -- to
tunnel the data. My guess is that in your second case, something is blocking
GRE communications.
In your first case, the ISP is probably blocking both GRE and 1723/tcp, but
that's just a guess.
___________________________________________________________
Steve Riley
Microsoft Telecommunications Consulting in Denver, Colorado
e-mail: mailto:[EMAIL PROTECTED]
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For MS Internet info see http://www.microsoft.com/isn/
Applying computer technology is simply finding the right wrench to pound in
the correct screw.
-----Original Message-----
From: Perez Lajo, Jacobo [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, February 29, 2000 10:31 AM
To: [EMAIL PROTECTED]
Subject: Ports used by PPTP ?
Hi all,
first of all, thanks to everybody who answered (and is still posting
answers) to my
previous question about the FW-1 bug.
Now I would like to know how the PPTP (Microsoft's implementation of VPNs)
behaves,
I mean, which ports are used for authoritation and which for the tunnel data
itself (the
standard). I am using a VPN Server in order to allow our remote offices to
use intranet
services; they (at a certain country) use an ISP to make the "call" to our
server, we have
already twelve offices connected in this fashion but the last two have
found problems:
- The first case is clear, the ISP told us that it is forbidden to use this
protocol (here is
the question, which ports are they blocking to forbid the service? )
- The second, which I think that could had something to do with this, is as
follows:
When we make the call it seem out to reach the server (it is possible to
reach it
by other means) and just when it is suppoused to have verified
username&pass. it crashes
with the error message : " [...] the peer is not responding.]". They get
this message 90% of the
time they waste making calls every 60 seconds ... sometimes, without further
explanation, they
succeed in connecting.
Any idea? ... in that country it is quite a hard task to find someone at the
ISP(the one and only)
to give you an explanation ... this is the reason of the post ... Thanks in
advance.
/|||\
@ @
---------------oOOo--(_)--oOOo------------------
Jacobo P�rez Lajo
�rea de Sistemas y Comunicaciones
CISICRET
Tel: +34 91 3436132
[EMAIL PROTECTED]
[EMAIL PROTECTED]
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