My company has implemented a Point-to-Point VPN for all of our offices. Our London office keeps losing connection....
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I'd like to be able to check their router and see if the proper ports are opened. BT owns the router and won't let us configure it and I have a feeling they're being less then truthful about the config. How can I check to see the port settings? Hi Frank, I see this problem all the time when trying to set up a VPN where someone else controls the router or firewall. So you're not alone. Although it does sometimes occur that a large carrier may be misleading you, it's more than likely that the person you were talking to is simply mistaken.
A relatively straightforward way to see if the port is open and forwarding properly is to:
- Set up a server inside your firewall and/or router that can accept telnet requests.
- Assign the server the IP address that you would have normally assigned to your VPN gateway and have it listen on the appropriate ports for telnet requests.
- From inside the firewall, on the same network, establish a telnet session with the server. If this works, you're ready for the outside test. If not, make sure that you have everything set up correctly before continuing.
- From outside the firewall, initiate a telnet session to the server address (if it is a public address) or to the firewall address (if you're using port forwarding and/ a server has a private IP address). If the telnet session works, then ports are open. If not, then they are closed or not forwarding properly.
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