use strict;
use warnings;

my $mask = '\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}';
while (<DATA>) {
    chomp;
    if (@_ = m/permit ip(?: host)?\s+($mask)\s+($mask)\s+($mask)(?:\s+
+($mask))?$/) {
        no warnings 'uninitialized';
        if ($2 eq '192.168.100.0' && $3 eq '0.0.0.255' ||
            $3 eq '192.168.100.0' && $4 eq '0.0.0.255') {
            print "@_\n";
        }
    }
}

__DATA__
permit ip host 10.11.1.1 192.168.100.0 0.0.0.255
permit ip 10.11.1.0  0.0.0.255 192.168.100.0 0.0.0.255
[download]