I tried using my $fk = "$ff" . ':255.255.255.0';. I also tried using chomp; But no help in both the cases.
I know my regex will matches more than just the Ip addresses like 2223.9991.55654.11111, but i damn sure it will match each and every IP address on the planet. And it is doing it correctly since i am getting the correct IP in $ff.
Now, for more troubleshooting i tried printing $ff & $fk and i got the below results, i am not sure what is wrong here
$block4 = Net::Netmask->new2($fk);
Can't call method "size" on an undefined value at save.txt line 55, <F
+> line 23.