use warnings;
use strict;
use Socket;
my ($remote,$port, $iaddr, $paddr, $proto, $line);

$remote  = $ARGV[0] || die "usage: $0 hostname";
$port    = 22 ;  # the SSH port
$iaddr   = inet_aton($remote) || die "no such host: $remote";
$paddr   = sockaddr_in($port, $iaddr);
$proto   = getprotobyname('tcp');

socket(SOCK, PF_INET, SOCK_STREAM, $proto) || die "socket() failed: $!";
print "Connecting to port 22...\n";
connect(SOCK, $paddr) || die "connect() failed: $!";
print "Connected.\n";
$line = <SOCK>;
print $line;
exit 0 if $line =~ /SSH/;
exit 1;

##</code><code>##

$ perl sshping.pl localhost; echo $?
Connecting to port 22...
Connected.
SSH-1.99-OpenSSH_x.xx Debian-xxx
0

##</code><code>##

$ perl sshping.pl localhost; echo $?
Connecting to port 22...
connect() failed: Connection refused at sshping.pl line 14.
111

##</code><code>##

$ if perl sshping.pl localhost; then echo up; else echo down; fi
Connecting to port 22...
connect() failed: Connection refused at sshping.pl line 14.
down