#!/bin/bash
###############################################
#
# Nagios script to check network I/O status

# Copyright Juned Memon

# See usage for command line switches

#
#
# 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/>.
#
###############################################

. /usr/local/nagios/libexec/utils.sh


VERSION="1.1"

GREP=/bin/grep
CUT=/usr/bin/cut

FLAG_VERBOSE=FALSE
interface=""
LEVEL_WARN="0"
LEVEL_CRIT="0"
RESULT=""

received_bytes=""
old_received_bytes=""
transmitted_bytes=""
old_transmitted_bytes=""

warn=20000  # i.e 20Kbps
crit=15000  # i.e 15KBps


###############################################
#
## FUNCTIONS
#

## Print usage
usage() {
        echo " check_netio $VERSION - Nagios network I/O check script"
        echo ""
        echo " Usage: check_netio {-i} [ -v ] [ -h ]"
        echo ""
        echo "           -i  Interface to check (e.g. eth0)"
        echo "           -v  Verbose output (ignored for now)"
        echo "           -h  Show this page"
        echo ""
}

## Process command line options
doopts() {
        if ( `test 0 -lt $#` )
        then
                while getopts i:vh myarg "$@"
                do
                        case $myarg in
                                h|\?)
                                        usage
                                        exit;;
                                i)
                                        interface=$OPTARG;;
                                v)
                                        FLAG_VERBOSE=TRUE;;
                                *)      # Default
                                        usage
                                        exit;;
                        esac
                done
        else
                usage
                exit
        fi
}


# This function parses /proc/net/dev file searching for a line containing $interface data.
# Within that line, the first and ninth numbers after ':' are respectively the received and transmited bytes.
function get_bytes
{
    line=$(cat /proc/net/dev | grep $interface | cut -d ':' -f 2 | awk '{print "received_bytes="$1, "transmitted_bytes="$9}')
    eval $line
}


# Function which calculates the speed using actual and old byte number.
# Speed is shown in KByte per second when greater or equal than 1 KByte per second.
# This function should be called each second.
function get_velocity
{
    value=$1
    old_value=$2

    let vel=$value-$old_value
    let vel=$vel*8
    #let velKb=$vel/1000
    #velKb=$(echo "scale=3; $vel/1000.0" | bc ) # Convert to decimal.
    #if [ $velKb != 0 ];
    #then
 #echo -n "$velKb Kb/s";
    #else
 #echo -n "$vel b/s";
   # fi
echo -n "$vel";
}

# Write output and return result
theend() {
        echo -en $RESULT
        exit $EXIT_STATUS
}



# Handle command line options
doopts $@

# Do the do

get_bytes
old_received_bytes=$received_bytes
old_transmitted_bytes=$transmitted_bytes
sleep 1;
# Get new transmitted and received byte number values.
get_bytes
    # Calculates speeds.
    vel_recv=$(get_velocity $received_bytes $old_received_bytes)
    vel_trans=$(get_velocity $transmitted_bytes $old_transmitted_bytes)
    

     vel_recvKb=$(echo "scale=3; $vel_recv/1000.0" | bc ) # Convert to decimal
     vel_transKb=$(echo "scale=3; $vel_trans/1000.0" | bc ) # Convert to decimal 


    let vel_total=$vel_recv+$vel_trans
    
    vel_totalKB=$(echo "scale=3; $vel_total/1000.0" | bc ) # Convert to decimal  
    #vel_total=$(echo "scale=3;$vel_recv+$vel_trans" | bc ) 
    #RESULT="NETIO OK : - $interface DOWN:$vel_recv\tUP:$vel_trans\n"


#if crit > vel >warn then warning
if [ $vel_total -lt $crit ]; then
if [ $vel_total -ge $warn ]; then
RESULT="NETIO WARNING: - $interface DOWN:$vel_recvKb Kbps\t UP:$vel_transKB Kbps \tTOTAL:$vel_totalKB Kbps\n"
exitstatus=$STATE_WARNING
#exit $exitstatus
fi
fi
# vel>crit then critical
if [ $vel_total -ge $crit ]; then
RESULT="NETIO CRITICAL: - $interface DOWN:$vel_recvKb Kbps \tUP:$vel_transKb Kbps \tTOTAL:$vel_totalKB Kbps\n"
exitstatus=$STATE_CRITICAL
#exit $exitstatus
fi

# 0<=vel <warn
if [ $vel_total -lt $warn ]; then
RESULT="NETIO OK : - $interface DOWN:$vel_recvKb Kbps \tUP:$vel_transKb Kbps \tTOTAL:$vel_totalKB Kbps \n"
exitstatus=$STATE_OK
#exit $exitstatus
fi




# Quit and return information and exit status
theend