use strict;
use warnings;

my @ips = qw(123.156.89.12 12.245.67.1 12.45.67.180 12.145.66.20);

@ips = sort {$a cmp $b} @ips;

print join "\n", @ips;
[download]

Prints:

12.145.66.20
12.245.67.1
12.45.67.180
123.156.89.12
[download]

is probably not what OP was after.