I've written a short script that checks to see if a remote server is listening on a specific TCP port. Its in the early stages, so some error checking needs to be built in. For now though, I'm confused by an error that I am getting when I test it using localhost as the guinea pig.

      1 #!/usr/bin/perl -w
      2 
      3 # $Id:$
      4 
      5 # check to see if server is listening on a tcp port
      6 
      7 use strict;
      8 use IO::Socket;
      9 
     10 my @servers = qw(localhost);
     11 
     12 my %ports =     (
     13                         telnet  => "23",
     14                         smtp    => "25",
     15                         pop3    => "110",
     16                         named   => "53",
     17                         http    => "80",
     18                         https   => "443",
     19                 );
     20 
     21 my $proto = "tcp";
     22 my $disco = 0;
     23 
     24 for my $host(@servers) {
     25 
     26   my $ip = gethostbyname($host);
     27   my $ip_addr = inet_ntoa($ip);
     28 
     29   for my $service(keys %ports) {
     30 
     31     my $disco = 0;
     32 
     33     my $checkport = IO::Socket::INET->new(
     34       PeerAddr  => "$ip_addr",
     35       PeerPort  => "$ports{$service}",
     36       Proto     => "$proto",
     37       Timeout   => '0')
     38         or $disco = "1";
     39 
     40     print "$host FAILED to repond on $service $ports{service}\
+n"
     41       if $disco;
     42 
     43     close $checkport;
     44 
     45   }
     46 }
[download]

When I run the script, I get:

Use of uninitialized value in concatenation (.) at ./chkport.pl line 4
+0.
localhost FAILED to repond on telnet 
Can't use an undefined value as a symbol reference at ./chkport.pl lin
+e 43.
[download]

i'm staring at the print statement and the close statement. Both seem to be correct to the best that I can tell. Your input is well appreciated as always.

humbly -c

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