Virtual Private Networks, Second Edition

Troubleshooting Problems

Now let us assume that everything didn’t go as smoothly as planned. There are several points of failure along the way, but fortunately there are some good ways to pinpoint the problem.

Errors from the VPN Script

The following are errors that might occur when you execute the VPN script. All of these errors should appear directly on the screen. When looking at these errors, it’s important to remember the essentials of what the VPN script does: it redirects a pseudo-terminal, launches the PPP daemon on the slave using SSH, launches the PPP daemon on the master, and sets up routing on both the master and slave.

FAILED!

If you see this message, pty-redir failed to get a valid pseudo-terminal. You should check the contents of the /tmp/device file and see if it’s empty. If it exists but is empty, and you actually saw pty-redir spit out a device name when you ran it by hand earlier, STDERR output may not be redirected to that file. You will have to add a 2 as we showed under Section 8.4.2.7.

SIOCADDR: Network is unreachable

This is a message from one of the route commands. It can mean there is a mistake either in one of the IP addresses or networks in the VPN script settings, or in the slave’s route script. Or it could mean that a PPP connection was never successfully started, in which case you’ll need to check the logs (see Section 8.5.2).

SIOCADDRT: Operation not permitted

This is also a message from one of the route commands. It means that you’re not allowed to execute ...