One of the nice things about the --ifconfig option is that it lets you set TUN adapter endpoint addresses (i.e. the virtual IP addresses for each end of the tunnel) in a platform independent manner -- OpenVPN then translates the --ifconfig option to the appropriate ifconfig command for your platform.
Up until now, the --ifconfig option has only worked for TUN adapters, but with the increasing use of TAP adapters for ethernet bridging, and the fact that the new Windows port only supports a TAP adapter, I've decided to extend --ifconfig so that it works for TAP devices as well (this feature will be included in 1.5-beta8). --ifconfig is really a convenience function -- you can call ifconfig yourself in an --up script, but letting OpenVPN run the ifconfig command for you makes the configuration simpler and more portable. The new --ifconfig will still work as always with --dev tun. However if --dev tap is specified, then the --ifconfig option will be interpreted as --ifconfig ip-addr netmask. What I need right now in order to make the TAP version of --ifconfig work correctly, is the correct ifconfig command syntax for setting the IP address and netmask of a TAP device, on all the OSes which OpenVPN supports. I've already coded templates for Linux and Windows, but I still need to know the appropriate ifconfig syntax for FreeBSD, OpenBSD, NetBSD, Solaris, and Mac OS X, with respect to setting the IP/netmask on a TAP device. So if you are using one of these OSes with OpenVPN + TAP adapter, please let us know what kind of ifconfig syntax you use in your --up script to set the adapter parameters. James
