http://qs1969.pair.com?node_id=1138169

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

Hello

I want to have a script in perl that is running in windows that test the connection to a ssh server.

If the ssh is up and running I need it to display the version. If ssh timeout I need it say socket timeout after x seconds If the connection is refused. simple display Connection refused.

I have the following bit of code that displays the version but I do not know how to handle the errors (timeout and connection refused

#!C:\Dwimperl\perl\bin\perl

use IO::Socket::INET;
use strict;
use warnings;

my $socket = IO::Socket::INET->new(
  PeerHost => $np->opts->host,
  PeerPort => $np->opts->port,
  proto    => 'tcp',
  timeout  => 10,
);
die "$!\n" unless $socket;

$socket->print("\n");
 my $output = join '', $socket->getline();

 print $output;

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also, the timeout is taking more than 10 seconds..so I do not think that is working.

Replies are listed 'Best First'.
Re: test version of ssh from windows
by stevieb (Canon) on Aug 11, 2015 at 15:05 UTC

    Wrapping the socket operations within an eval block will help fix both issues. First, if connection is refused, the error will be put into $@ for later processing if you desire. Second, the timeout effect I believe you're after can be achieved with a local alarm signal handler, and setting the number of seconds before the alarm is raised (this error will also be put into $@ if triggered)...

    #!/usr/bin/perl
use strict;
use warnings;

use IO::Socket::INET;

eval {

    local $SIG{ALRM} = sub { die 'timeout'; };
    alarm 10;

    my $socket = IO::Socket::INET->new(
      PeerHost => $ARGV[0],
      PeerPort => 22,
      Proto    => 'tcp',
    );

    die "$!\n" unless $socket;

    $socket->print("\n");

    my $output = join '', $socket->getline();

    print $output;
};

# if eval set an error... handle it

if ($@){
    ... if $@ eq 'timeout';
    ... if $@ eq 'Connection refused';
}

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    -stevieb

    ps. Note that in the IO::Socket::INET documentation, all of the parameters start with an upper-case letter (you mistyped 'Proto' and 'Timeout'). I don't know whether that's operationally important or not in this case, but I wanted to point it out. Not using an API according to the documentation can lead to incorrect results.

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Re: test version of ssh from windows
by naunga (Initiate) on Aug 11, 2015 at 15:10 UTC

    I ran your code on my OS X machine, and it worked in the way you described that you wanted it to work.

    I got a success, I tried an invalid port and got a "connection refused" message, and I tried an invalid host and got an "Invalid argument" message.

    Feels like this is an issue with host & port you're trying to connect to, instead of a code probelm.

[reply]
      Hello

      it works but the messages are too long.

      I do not know if I can change the text of the variable $!?

      .

      This script will be integrated into nagios later with nsclient and nrpe so the messages have be short.

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        In my reply above using eval, you can trap and then reword the errors as you see fit. Here's a short example.

        eval {
    open my $fh, '<', 'asdf' or die $!;
};

if ($@ =~ /No such file or directory/){
    print "short error msg\n";
    # or...
    die "short msg";
}

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Re: test version of ssh from windows
by Anonymous Monk on Aug 11, 2015 at 15:05 UTC
    What is $np in this piece of code?
[reply]
      The host and port information. It just appears as though it was left in by accident after being snipped out of a larger script.
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