check_tcp_established

#!/usr/bin/perl

##################
#
#  Check established TCP connections for port 1883 (mosquitto)
#
#  Usage:   ...
#
#  Be careful! Parameters are passed to the shell using qx//
#
#  Copyright (C) 2024 Bernd Arnold
#  https://github.com/wopfel/monitoring-plugins
#
##################

use strict;
use warnings;
use Data::Dumper;
use Getopt::Long;

# Sub routines
sub print_help();

my $opt_verbose;
my $opt_help;

my $answer = "";
my $crit_count = 0;
my $warn_count = 0;
my $status = "Unknown";
my @perfdata = ();
my @additional = ();


#
# Process command line options
#

GetOptions( "v|verbose"          => \$opt_verbose,
            "help"               => \$opt_help,
          )
or do { print STDERR "Error in command line argument processing. Try '$0 -help'.\n"; exit 4; };

if ( $opt_help ) {
    print_help();
    exit 4;  # Outside of the official monitoring plugin's exit codes
}


#
# Query network
#

my $output = qx{ ss -ntp --no-header state established src :1883 };
print Dumper( $output ) if $opt_verbose;

my $count = 0;

for my $line ( split /\n/, $output ) {
    $count++;
}

$answer .= "$count connections. ";

push @perfdata, "connections=$count";


#
# Check results
#

# TODO


###

if ( $crit_count ) {
    $status = "Critical";
} elsif ( $warn_count ) {
    $status = "Warning";
} else {
    $status = "Ok";
}

print "$status: ";
print "$answer\n";

print "| " . join(" ", @perfdata) . "\n"  if @perfdata;
print join("\n", @additional) . "\n"  if @additional;

exit 2 if $status eq "Critical";
exit 1 if $status eq "Warning";
exit 0 if $status eq "Ok";
exit 3;  # 'Unknown' return code



#
# Print help
#

sub print_help() {

    print STDERR <<~"END"
    Check established network connections on port 1883 (mosquitto)

    Usage: $0

    Example: $0
             Just show the values


    Parameters:

        -h, --help         Show this help text
        -v, --verbose      Verbose output (for debugging)

    END

}