ifdl is a wrapper for ifup that handles multiple network configurations. It is primarily useful for portable machines or for test lab machines where a network topology changes on a regular basis. Because the computer doesn't know at boot time what network it is going to be connected to, ifdl is run by the user. The user must specify what network to use or it will just bring up the specified interface for the last network that was brought up.

The basis of the tool is a list of files that get overwritten by network specific versions of those files. The listing of files is stored in /etc/ifdl.conf. Additional files can be added to the configuration. What gets installed is just a default config.

The tool requires the user to have permission to write to the file locations listed in /etc/ifdl.conf. This can be accomplished by running ifdl as sudo, running as root, or changing the file permissions such that the user has write permissions. Running as sudo is probably the most secure method.

ifdl takes a number of command line options. Currently these consist of the following, but always run 'ifdl -h' to see what the current options are.

• -b back up conf files to prevent accidental destruction
• -f force overwrite conf files
• -h help
• -l lists all defined network locations (based on /etc/network/interfaces.*)
• -v pass --verbose flag to ifup

ifset allows the user to change networks without actually bringing an interface up. It behaves like ifdl except it doesn't require an interface to be specified and doesn't have the ifup specific flags.