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New Member

VPN through 802 ISDN router.

I am new to Cisco routers and this is probably basic stuff for most of you, but I need to know what steps to take to VPN through a CISCO 802 router from the internet so my remote laptop users can connect.

My configuration is this Remote User---ISP---Cisco 802 (using dynamically assigned WAN address and public ethernet address)---public ethernet north side of Microsoft VPN/ISA firewall server.

I am currently running IOS 12.0 (5) with just basic IP feature set. Just to get up and running, I would like to establish just a PPTP (using GRE protocol) VPN tunnel through the router to the VPN server.

What steps do I need to take? - such as do I need any port forwarding and how? How do I allow GRE protocol 47 through? Should I be able to ping public address of VPN server? It seems as through right now, I can only hit router IP ethernet address and nothing further. Also, do I need to purchase another feature set for this or if I wanted to allow IPSEC to go through the router? Thanks.

Cisco Employee

Re: VPN through 802 ISDN router.


Firstly you got to make sure that if there is any access-list applied on the Router that it doesn't block the tcp port 1723 or GRE traffic. Additionally if you are not able to ping the Microsoft VPN server then you might need to define a Static NAT on the Router for that, which can be configured as:

Hope this helps,



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