Linux Training

#!/bin/bash
# $Id: portmon,v 1.29 2014/12/30 15:29:12 fulford Exp $
# $Source: /src/merlin/usr/local/etc/RCS/portmon,v $
# $Revision: 1.29 $
# $Date: 2014/12/30 15:29:12 $
# Author C W Fulford.
# Copyright 2013,2014 (c) C W Fulford.
# Licensed for public use under the LGPL, .
# For assistance contact fulford@fulford.net 0709 229 5385
########################################################################
cmd=`basename $0`
ver=`echo "$Revision: 1.29 $" |awk '{print $2}'`
date=`echo "$Date: 2014/12/30 15:29:12 $"|awk '{print $2,$3}'`
syntax="$cmd [-c <config_file>] [-d] [-l] [-p #] ] [-v] <host_id>|-V"
while [ $#  -gt 0 ];do
	case $1 in
		-c)config=$2;shift 2;;
		-d)debug=:;set -x;shift;;
		-l)syslog=:;shift;;
		-p)port=$2;shift 2;;
		-v)verbose=:;shift;;
		-V)echo "$cmd $ver $date";exit ;;
		*) hostid=$1;shift;;
	esac
done

config=${config:-/usr/local/etc/portmon.cf}
if [ -r $config ];then
	eval `sed -ne '/^'$hostid':/,/^$/{/^[ 	]/p}' $config`
fi
port=${port:=110}
[ -z "$host" ] && host=$hostid

_end () {
     logger -t $cmd "$cmd port $port on $host stopped `date`"
     exit 1
}

trap "_end" 1 15

nslookup $host >/dev/null ||{
	echo "$cmd: can't resolve hostname $host">/dev/null
	exit 1 
}
	
[ "$verbose" ] &&{
	echo "$cmd started monitoring $port on $host `date`"
}
[ "$syslog" ] &&{
	logger -t $cmd "started monitoring $port on $host `date`"
}

while : ;do
	if nmap -Pn -p$port dougal|grep closed>/dev/null ;then
		msg="port $port on $host down `date`"
		[ "$verbose" ] && echo $msg
		[ "$syslog" ] && logger -t $cmd "$msg"
		while nmap -Pn -p$port dougal|grep closed >/dev/null ;do
			[ "$verbose" ]&&{
				echo "$cmd: $port still closed"
			}
			sleep 180
		done
		msg="port $port on $host recovered `date`"
		[ "$verbose" ] && echo $msg
		[ "$syslog" ] && logger -t $cmd "$msg"

	fi
	[ "$verbose" ] && echo "port $port on $host up `date`"
	sleep 300
done
######################################################################
# This program is free software: you can redistribute it and or      #
# modify it under the terms of the Lesser 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.                       #
#                                                                    # 
# A copy of the Lesser GNU General Public License and the GNU        #
# General Public License is available at                             #
# <http://www.gnu.org/licenses/>.                                    #
######################################################################