How to test GRE nd PPTP

How to test GRE and PPTP using PPTPsrv and PPTPclnt

PPTP VPN tunnel requires that the both VPN server and client opening TCP port 1723 and IP protocol 4. If these ports don’t open, the VPN client may receive the following messages: VPN Error 628 - The port is disconnected, VPN Error 721 - Remote PPP peer or computer is not responding and VPN Error 800 - Unable to establish the VPN connection.

Windows 2000 includes a PPTP Ping tools, PPTPsrv and PPTPclnt, that you can install them from the support\tools folder of the Windows 2000 CD-ROM. PPTPsrv and PPTPclnt provide basic diagnostic functionality that lets you determine whether both VPN server and client can reach each other across the Internet. Therefore, you can use PPTPsrv and PPTPclnt to ensure that the proper ports are open on the firewall and that the remote server is successfully receiving incoming client connection requests.

To do so, you can run pptpsrv on the VPN by typing on command prompt while running pptpclnt <server name or IP> on the VPN client. If the connection and packet transfer succeeded, the server will display the following output

Total GRE packets received = 1

Total GRE packets received = 2

Total GRE packets received = 3

Total GRE packets received = 4

Total GRE packets received = 5

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GRE protocol test was successful!

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Closing socket

Goodbye!

If the VPN server and client can’t reach each other, the server will display an error message.

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