#! /usr/bin/perl

# multimonitor.pl
# monitor http,https,smtp on remote servers.

use strict;
my (@rwebhost,@rswebhost,@rmailhost,$key,%host);

# http
%host = ();
push @rwebhost,"coolsite.com","notcoolsite.com","sheepydeepy.com";
foreach (@rwebhost) {
  %host = ($_ => &getips($_));
  foreach $key (keys %host) {
    &scan_httpd($host{$key},$key);
  }
}

# https
push @rswebhost,"secure.coolsite.com";
foreach (@rswebhost) {
  %host = ($_ => &getips($_));
  foreach $key (keys %host) {
    &scan_httpsd($host{$key},$key);
  }
}

# smtp
push @rmailhost,"mail.sheepydeepy.com";
foreach (@rmailhost) {
  %host = ($_ => &getips($_));
  foreach $key (keys %host) {
    &scan_smtp($host{$key},$key);
  }
}

sub getips() {
  my $host = shift;
  my ($name,$aliases,$addrtype,$length,@addrs,@ips);
  (($name, $aliases, $addrtype, $length, @addrs) = gethostbyname($host))
          || &email_resolution_error($host);

  foreach (@addrs) {
    @ips = join('.',unpack('C4',$_)),"\n";
    return @ips;

  }
}

# ===================================
sub scan_httpd() {

  # Scan for HTTP service.
  my @ips       = shift;
  my @hostname  = shift;
  my $port      = "80";
  for (my $i = 0; $i < @ips; $i++) {
    my @results = `/usr/bin/nmap -P0 -p$port -oG - $ips[$i] | grep \"Status: Up\"`;
    for (@results) {
      &email_connection_error($hostname[$i]) if $_ =~ $ips[$i];
    }
  }
}

sub scan_httpsd() {
  # Scan for HTTPS service.
  my @ips       = shift;
  my @hostname  = shift;
  my $port      = "443";
  for (my $i = 0; $i < @ips; $i++) {
    my @results = `/usr/bin/nmap -P0 -p$port -oG - $ips[$i] | grep \"Status: Up\"`;
    for (@results) {
      &email_connection_error($hostname[$i]) if $_ =~ $ips[$i];
    }
  }
}

sub scan_smtp() {
  # Scan for SMTP service.
  my @ips       = shift;
  my @hostname  = shift;
  my $port      = "25";
  for (my $i = 0; $i < @ips; $i++) {
    my @results = `/usr/bin/nmap -P0 -p$port -oG - $ips[$i] | grep \"Status: Up\"`;
    for (@results) {
      &email_connection_error($hostname[$i]) if $_ =~ $ips[$i];
    }
  }

}
sub email_resolution_error() {
my $rnode = shift;
my $hostname = `/bin/uname -n`;
chomp($hostname);



open(SENDMAIL, "|/usr/lib/sendmail -oi -t")
   or die "Cannot fork for sendmail: $!\n";

print SENDMAIL <<EOF;
From: Multi-Monitor <nobody\@monitor.domain.com>
To: System Admin <someone\@anotherdomain.com>,somemobile\@otherdomain.net
Subject: The domain $rnode cannot be resolved!
   
This email is generated by the Multi-Monitor script on $hostname...
WARNING: The domain $rnode cannot be resolved!
  
EOF

close(SENDMAIL) or warn "Oops, sendmail did not close nicely";
}

sub email_connection_error() { 
my $hostname = `/bin/uname -n`;
my $remote_server = shift;
chomp($hostname);
chomp($remote_server);


# switch $remote_server back to a hostname.

open(SENDMAIL, "|/usr/lib/sendmail -oi -t")
   or die "Cannot fork for sendmail: $!\n";
    
print SENDMAIL <<EOF;
From: Multi-Monitor <nobody\@monitor.domain.com>
To: System Admin <someone\@anotherdomain.com>,somemobile\@otherdomain.net
Subject: Connection Trouble on $remote_server!

  
This email is generated by the Mulit-Monitor script on $hostname...
WARNING: $remote_server cannot be contacted!

EOF

close(SENDMAIL) or warn "Oops, sendmail did not close nicely";
}