Testing ports

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

Anyone got a quick script to check which ports are functioning on a range of hosts? I've lost the IP of a router on a class C network, I'd like to try connect to the telnet port of each ip and see which ones accept telnet connections. something like:

$lip = 1;
while ($lip >= 254) {
 $ip = "192.169.128." . $lip;
   -----ATTEMPT TO CONNECT TO TELNET PORT HERE, PRINT SOMETHING IF SUC
+CESSFULL, OTHERWISE, NEXT.....

$lip++;
}
[download]

Easy to think up, another thing to do....

Comment on Testing ports Download Code

Replies are listed 'Best First'.
Re: Testing ports by tomhukins (Curate) on Mar 01, 2001 at 19:07 UTC
You could use IO::Socket (see The Caller section of Perl, Sockets and TCP/IP Networking) to attempt to connect to port 23 of `$ip`. If you're running Unix, you should look into nmap, which is designed to do this job for you.	[reply]
Re: Testing ports by rpc (Monk) on Mar 01, 2001 at 22:59 UTC
Caveat: If you're going to use `IO::Socket`, you will also need to read the pod for `IO::Select` to keep `connect()` from blocking, when you reach a host that is down or has port 23 firewalled. I agree to the above post, nmap is a much better solution. Also, nmap logfiles are easily parsable in Perl.	[reply] [d/l] [select]