Virtual Private Networks, Second Edition

Troubleshooting Problems

What do you do if your system doesn’t connect? Is the trouble with your remote user’s ISP, the Central Office’s ISP, with the Internet itself, or with the configuration on the RAS client or server? Because of all the factors involved, problems with VPN connections are some of the most difficult to track down.

Login problems

For dial-up RAS users, the most common problem in getting connected is working with the modem. In that case, all troubleshooting can be done on the client side. Authentication problems (bad usernames or passwords, or incorrect authentication type) follow shortly thereafter, and often require that someone look through the logs or watch the connection attempt at the destination RAS server. Windows NT’s Event Viewer and Dial-Up Networking Monitor help you isolate such login problems.

The Event Viewer

The Event Viewer is the common logging system on all Windows NT machines. It can be found from the Start menu under Programs → Administrative Tools. Let’s say that Sara N. is having trouble dialing in—she seems to be having negotiation problems and isn’t sure why. When you bring up the Event Viewer, look at the Source column for any RemoteAccess messages that occurred at the approximate time she was attempting to dial in. In the left-hand column, there are icons that distinguish informational messages (an “i” encircled in blue), from warning messages (an exclamation mark encircled in yellow), and from error messages (a red STOP sign). You see ...