If you're using TUN/TAP on a platform other than Linux-2.4, see
http://vtun.sourceforge.net/tun/
+You will probably be using the supplied `make-secnet-sites' program to
+generate your VPN's list of sites as a secnet configuration from a
+more-human-writeable form. If so you need to install the standard
+`ipaddr' Python module (python-ipaddr on Debian-derived systems).
+
** System and network configuration
If you intend to start secnet as root, I suggest you create a userid