FreeBSD IP Alias: Setup 2 or More IP address on One NIC

Set ip alias using ifconfig command line utility

Login as the root user.

Now, use ifconfig command as follows to set alias:
# ifconfig lnc0 192.168.1.5 netmask 255.255.255.255 alias
Persistent IP Alias Configuration

Edit file /etc/rc.conf to setup persistent ip aliasing option by appending following configuration, so that next time FreeBSD comes up (after restart/shutdown) it will create alias for you:
ifconfig_lnc0_alias0="192.168.1.5 netmask 255.255.255.255"

Finally, Restart FreeBSD network service using network restart script:
# /etc/rc.d/netif restart && /etc/rc.d/routing restart
Display alias and real ip using ifconfig lnc0 command:
# ifconfig lnc0