Configuring Multiple IP Addresses on a single Network Interface

multi-address.nic.sh

#!/usr/bin/env bash 
#
# There are many custom use cases that require 
# assigning multiple 'virtual' IP addresses to 
# a single network interface.
# 
# One case in particular, is for developing web applications 
# locally on a workstation, to support a project that has multiple 
# sub-domains. In such a case, you would create virtual IP addresses 
# to support virtul hosts in apache/nginx. You would then associate the 
# sub-domains to the virtual IP addresses, in your /etc/hosts file.
#
# example:
#
# 192.168.1.11 mysite.net
# 192.168.1.12 subdomain1.mysite.net
# 192.168.1.13 subdomain2.mysite.net
#
# This allows you to stage network connectivity (locally) during
# development and testing.
#

# Assign the initial 'physical' address of the NIC
ifconfig eth1 192.168.1.1 netmask 255.255.255.0 &
ifconfig eth1 up

# assign 192.168.1.11 to eth1:1 
ifconfig eth1:1 192.168.1.11 netmask 255.255.255.0 & 
ifconfig eth1:1 up 
 
# assign 192.168.1.12 to eth1:2 
ifconfig eth1:2 192.168.1.12 netmask 255.255.255.0 & 
ifconfig eth1:2 up 
 
# assign 192.168.1.13 to eth1:3 
ifconfig eth1:3 192.168.1.13 netmask 255.255.255.0 & 
ifconfig eth1:3 up