Another quick hint. While working on a server I needed to bring up a whole lot of IP addresses (200 to be exact). If I really wanted to I could bring them all up like this:
ifconfig eth0:2 1.1.1.2 netmask 255.255.255.0 up
ifconfig eth0:3 1.1.1.3 netmask 255.255.255.0 up
and so on to…..
ifconfig eth0:200 1.1.1.200 netmask 255.255.255.0 up
Well, I’m always looking for an easier way, so I turned to my friend BASH and a tool called SEQ. SEQ will give you a sequence of numbers. For example if you just wanted 10 numbers you could do the following:
[matt@localhost ~]$ seq 5
1
2
3
4
5
So for this task I needed to bring up IP addresses from 2 through 254. Running “seq 2 254″ will give me a sequence from 2 to 254, I need more than just to have a list of numbers, I actually need to use them, so here’s the syntax I used to use the numbers to bring up each of the interfaces
for i in $(seq 2 254)
do
ifconfig eth0:$i 1.1.1.$i netmask 255.255.255.0 up
done
Obviously in the above example, you would substitute the sequence you want to use and the IP subnet you want to use. Also, this syntax would put 1.1.1.2 on sub-interface eth0:2, 1.1.1.3 on sub-interface eth0:3, etc.
