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

ive wanted to check whether or not my other servers are showing the SSH & TELNET VERSIONS upon each session requests. ive already made my code on SSH first because it goes the same for TELNET too.(u just need to substitue a few things) 
#!/usr/bin/perl -w
use IO::Socket;
$remote = IO::Socket::INET->new(
        Proto => "tcp",
        PeerAddr => "210.212.226.195",
        PeerPort => "ssh(22)",
    ) || die "cannot connect";
$remote->autoflush(1);
while (defined ($line = <$remote>)) 
{
  print STDOUT $line;
}
$remote->exit(0);
print "Hello World!";

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the thing is... the socket process doesnt terminate prematurely and at the same time go to the next process. it just hangs there. got any ideas?

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Re: how to terminate an IO:Socket Process prematurely?
by Aristotle (Chancellor) on Jun 02, 2002 at 18:17 UTC

    Obviously because your while loop never terminates. After reading the first line of input, the $line = <$remote> blocks, waiting for more input that never comes.

    Three notes:
    1. You should use strict;
    2. I can't find any mention of an exit() method in the IO::Socket module documentation and it isn't strictly necessary either since IO::Socket will clean up after you at program termination (as do all well-behaved modules).
    3. Your autoflush() has no effect since you're not writing anything onto the socket that might get buffered in the first place.

    Update: I think what you want to do is more like this: 
    #!/usr/bin/perl -w
use strict;
use IO::Socket;

my $remote = IO::Socket::INET->new(
        Proto => "tcp",
        PeerAddr => "210.212.226.195",
        PeerPort => "ssh(22)",
    ) || die "cannot connect";

sysread($remote, my $line, 4*1024) or die "couldn't read any data"; # 
+one single attempt to read 4k of data
print "$line\n";

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    ____________
    Makeshifts last the longest.
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Re: how to terminate an IO:Socket Process prematurely?
by kodo (Hermit) on Jun 03, 2002 at 07:13 UTC
    close($remote); should do the job, but then $remote is gone completly of course.

    giant
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      its me again, CHARLIE. anyway, i found a workaround in my problem. i found the command SHUTDOWN. heres my code: 
      #!/usr/bin/perl -w

use IO::Socket;

$host="202.46.24.25";
$port="21";
#$flags=100;

while ($port<24)
{
  $remote = IO::Socket::INET -> new (
             Proto => "tcp",
             PeerAddr => $host,
             PeerPort => $port
             ) ;

  if ($remote) { 

#    $remote->recv($line, $flags) or die "Can't recv: $!\n";
#    sysread($remote, $line2, 4*1024) or die "couldn't read any data";
+ 
#    print $remote "test foo \n\n\n";
#    print $remote "\^\]\[\n\n\n";

    shutdown($remote, 1);     # can be 0, 1, 2    
    @line = <$remote>;

    close $remote;
    print "$host:$port=>\tActive\t@line\n";
#   print LOG "$host:$port=>\tActive\n";
#   push @active_ports, $port;
  }

  else 
  { 
    print "$host:$port=>\tInactive\n"; 
#   print LOG "$host:$port=>\tInactive\n";
  }  

$port=$port+1;
}

      [download]
      heres the sample output: 
      202.46.24.25:21=>       Active  220 cronus.wima.ac.id FTP server (Vers
+ion wu-2.6.1-20) ready.
 221 You could at least say goodbye.

202.46.24.25:22=>       Active  SSH-1.99-OpenSSH_2.9p2

202.46.24.25:23=>       Active  ÿýÿý ÿý#ÿý'

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      the thing is... its already working. but my friends box when queried on telnet isnt supposed to display ÿýÿý ÿý#ÿý'. i dunno why that thing comes out on telnet queries. my friend's box should display the following: 
      Trying 202.46.24.25...
Connected to 202.46.24.25.
Escape character is '^]'.
Red Hat Linux release 7.2 (Enigma)
Kernel 2.4.7-10 on an i686

      [download]
      so got any ideas? please.... no NET::Telnet ideas! tnx for the responses. ive already done my part donating a working code, hope it will be useful for some persons, but i really need to make that TELNET response captured properly. tnx again!
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