Mac OS X Server 1.0: Ethernet Interface Can Have Multiple IP Addresses

You may (as the Administrator, or root user) use the ifconfig command to add IP addresses to a single Ethernet interface. In this example, IP addresses other than the first IP address are added for the first Ethernet interface (en0).
Type the following commands in a Terminal window:

This takes the interface down and is required before changing configurations.

This adds additional IP address of 123.456.789.101 to this interface with netmask of 255.255.255.0

This brings the interface back up.

Test the new IP address by ping or telnet.

The ifconfig command may also be used to configure a port with a single IP address or change existing configurations. These steps are simpler to perform from Network Preferences (under the Apple menu).

More information about ifconfig is available by typing man ifconfig at the command prompt.

Note: Type the desired IP address in the place of 123.456.789.101 above.
Published Date: Feb 19, 2012