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Perl - Problem writing script to get status of open ports.

jpetter
jpetter asked
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Last Modified: 2013-11-05
Hi,
Some background - I do a lot of vulnerability scanning, and as part of the remediation, when the server admins which reports they have closed, I usually have to manually 'telnet <ip_address> <port>' to see if the port has been closed. Most of these are prod servers, so I cannot just rescan them, but would need to go through a much longer process.

To get around this, I am trying to write a perl script that will do this for me. Basically, I read in the address and port info from an Excel report, and then have tried various methods to try to duplicate the manual telnet process to determine if a port is open or not.

I have tried Net::Telnet, IO::Socket::INET, and a few others that are basically versions of these. I have found that neither produce consistent results, which most often means it's a "me" problem. If someone could point out how I could make this work, or propose an alternate method, I would greatly appreciate it.

I have included a couple snippets to show what I have been trying.

Thanks,
Jeff
.....
use Net::Telnet();
...........
...........
foreach (@hosts)
{
    my $host = $_;
    $telnet = new Net::Telnet();
    $telnet->open(Host => $host,
                  Port => $port);
    $telnet->errmode('return');
    if (($telnet->errmsg eq "") || ( "$telnet->errmsg\n" =~ /^Net::Telnet=GLOB\(0x([0-9a-fA-F]+)\)->errmsg$/ ))
    {
        printf "%s: %s\n", $host, ${\$telnet->errmsg};       #"open";
    }
    else
    {
        printf "%s: %s\n", $host, ${\$telnet->errmsg};
    }
    $telnet->close;
}
***********************************************************************
 
************************************************************************
....
use IO::Socket::INET;
......
.....
            foreach (@hosts)
            {
              my $host = $_;
              $socket = new IO::Socket::INET (
                                              PeerAddr => $host,
                                              PeerPort => $port
                                              );
              if ($socket)
              {
                printf ("%s:%s -- %s\n", $host, $port, "open");
              }
              else
              {
                 printf ("%s:%s -- %s\n", $host, $port, "closed");               
              }
              if ($socket)
              {
                close($socket);
              }
            }

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Commented:
Adam314,

Thanks again for the speedy response. I've added the proto and timeout options, and it seems to be working as expected now....and using the IO::Socket::INET as you recommended.

Thanks,
Jeff
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