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VPN Port numbers for firewall

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by courtney

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I want to have a Win2K VPN behind a firewall (ISA) what port numbers do I need to have open and are they in/outbound?

5 replies

by vergilius

Hi,

First, you have to determine whether you're using PPTP or L2TP. If you're using PPTP (which I'm using), you have to understand that PPTP uses a different IP protocol than TCP or UDP: it uses GRE packets.

In order to open up your firewall for PPTP, use the following:

Inbound TCP connections on port 1723 (that's for the setup phase)
In and outbound GRE packets

L2TP is quite a different beast. It uses IPSec in addition to GRE packets. I don't know much about it though.

Sven

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