FreeBSD uses only 1 configuration file to list your IP addresses and default gateway:
/etc/rc.conf
There is one line per IP address in this file. Secondary (alias) IP addresses are configured with a netmask of 255.255.255.255. Here’s an example of the lines you will need to have in /etc/rc.conf for 2 IP addresses:
ifconfig_fxp0=”inet 200.220.240.50 netmask 255.255.255.0″
ifconfig_fxp0_alias0=”200.220.240.51 netmask 255.255.255.255â€
Restarting network to re-read IP address configuration file:
/etc/netstart
