School assignment #5

networkCheck.pl

#!/usr/bin/perl
#
# Pinging a server and checking if Network services are up or down.

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

# Network services to check (dns will not resolv).
@services = qw/http https ssh telnet mail dns mysql/;

# Variables, argument 0 (first one) and executing server in *nix env.
die("Usage: ./pinghost.pl [IP|Hostname]") unless ($ARGV[0]);
$server = $ARGV[0]; 

# Open socket and check if it works
sub port_scan {
  # Assign array to list.
  ($addr, $port, $protocol) = @_;
  $portnum = getservbyname($port, $protocol);
  
  # If service could not be resolved return 0 (exit subroutine). 
  return 0 unless($portnum);

  # Open socket to $addr at $port on $protocol.
  $sock = IO::Socket::INET->new(PeerAddr => $addr,
                                PeerPort => $portnum,
                                Proto    => $protocol,
                                Timeout  => 2
                                );
  # Port up or down.
  print "$port ($portnum) is up.\n" if ($sock);
  print "$port ($portnum) is down.\n" if (!$sock);
}

# Resolve FQDN.
$hostname = gethostbyaddr(inet_aton($server), AF_INET);

# Print FQDN or errormsg.
print("$server FQDN is $hostname.\n") if($hostname);
print("FQDN for $server could not be resolved.\n") unless($hostname);

# Hold your horses, pinging server and sending output to /dev/null
system("ping -c 3 $server > /dev/null");

# If ping was successfull (returned 0) it is reachable.
if ( $? == 0 ) {
  print "$server is reachable.\n";
} else {
  print "$server is unreachable.\n";
  # Exit if server is unreachable.
  exit 0;
}

# Run subroutine port_scan to find out if service is up or down.
foreach $service(@services) {
  &port_scan($server, $service, "tcp");
}