#!/bin/sh -eu
#
# Plugin to monitor the number of hosts in /etc/hosts.deny
# that are denied access to sshd
#
# Based on denyhosts plugin by tjansson (2009)
#
# Copyright (C) 2009 Kåre Hartvig Jensen (kaare.hartvig.jensen@gmail.com)
# Copyright (C) 2019 Olivier Mehani <shtrom+munin@ssji.net>
#
# SPDX-License-Identifier: GPL-3.0-or-later
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
LOG=${LOG:-/etc/hosts.deny}

if [ "${MUNIN_DEBUG:-0}" = 1 ]; then
    set -x
fi

if [ "${1:-}" = "autoconf" ]; then
        if [ -r "${LOG}" ]; then
                echo yes
        else
		echo "no (${LOG} not readable or non-existent)"
        fi
        exit 0
fi

COUNTS=$(sed -n 's/^\([^#]\+\):.*/\1/p' "${LOG}" \
	| sort \
	| uniq -c \
	| sed "s/^.*\s\([0-9]\+\)\s\(.*\)/\2.value \1/"
	)

if [ "${1:-}" = "config" ]; then

        echo 'graph_title Hosts denied access'
        echo "graph_info Hosts denied access in ${LOG}"
        echo 'graph_args --base 1000 -l 0'
        echo 'graph_vlabel Hosts denied '
        echo 'graph_category security'
	# Assume we always have SSH
        echo 'sshd.label sshd'
        echo 'sshd.draw AREA'
	echo "${COUNTS}" \
		| sed '/ssh/d; # skip ssh
		       s/^\([^\.]\+\)\..*/\1.label \1\n\1.draw STACK/'
	if [ "${MUNIN_DIRTYCONFIG:-0}" != 1 ]; then
		exit 0
	fi
fi

echo "${COUNTS}"