or download this
use strict;
use warnings;
...
my @lines = ("ip:192.168.243.1", "ip:192.168.243.2" =~ /(ip:([0-9]{3}|
+[0-9]{2}|[0-9]{1})\.([0-9]{3}|[0-9]{2}|[0-9]{1})\.([0-9]{3}|[0-9]{2}|
+[0-9]{1})\.([0-9]{3}|[0-9]{2}|[0-9]{1}))/);
print "@lines\n";