check_netstat

#!/bin/bash
# ======================================================================
#
# Check NETSTAT and show connections
#
# requirements:
# - netstat
#
# ----------------------------------------------------------------------
# 2020-07-08  v1.0  <axel.hahn@iml.unibe.ch>
# 2022-10-25  v1.1  <axel.hahn@unibe.ch>  shell fixes; no tmpfiles; IML look
# ======================================================================


. $(dirname $0)/inc_pluginfunctions

self_APPNAME=$( basename $0 | tr [:lower:] [:upper:] )
self_APPVERSION=1.1

# ----------------------------------------------------------------------
# functions
# ----------------------------------------------------------------------

function showHelp(){
cat <<EOF
______________________________________________________________________

$self_APPNAME 
v$self_APPVERSION

(c) Institute for Medical Education - University of Bern
Licence: GNU GPL 3
______________________________________________________________________

Count number of network connections.

SYNTAX:
$(basename $0) [ -w value -c value -h ]

    -w VALUE       cpu usage warning level  (default: 75)
    -c VALUE       cpu usage critical level (default: 90)
    -h or --help   show this help.

PARAMETERS:

    None.

EXAMPLE:
$(basename $0) -w 60 -c 80 -p 40

If there is no -w and -c then the result is always OK.

EOF
}
# ----------------------------------------------------------------------
# MAIN
# ----------------------------------------------------------------------

# --- check required tools
ph.require netstat

# --- check param -h
case "$1" in
    "--help"|"-h")
        showHelp
        exit 0
        ;;
    *)
esac

# --- set optional limits
typeset -i iWarnLimit=$(     ph.getValueWithParam 0 w "$@")
typeset -i iCriticalLimit=$( ph.getValueWithParam 0 c "$@")

# --- count all connections
typeset -i iTotal=0
typeset -i iEst=0
typeset -i iListen=0
typeset -i iWait=0

netdata=$( (netstat -wltun; netstat -wtun) | awk '{ print $6 }' | grep -E '(ESTABLISHED|LISTEN|TIME_WAIT)' )
iTotal=$( echo "$netdata" | wc -l | awk '{ print $1 }')

if [ $iWarnLimit -gt 0 -a $iCriticalLimit -gt 0 ]; then 
    ph.setStatusByLimit $iTotal $iWarnLimit $iCriticalLimit
fi 

ph.status "NETSTAT - count of connections: $iTotal"


# --- add performance data
data2=$( echo "$netdata" | sort | uniq -c )
# result is something like that:
#      5 ESTABLISHED
#     10 LISTEN
#     77 TIME_WAIT
echo "$data2"

iEst=$(    echo "$data2" | grep ESTABLISHED | awk '{ print $1 }' )
iListen=$( echo "$data2" | grep LISTEN      | awk '{ print $1 }' )
iWait=$(   echo "$data2" | grep TIME_WAIT   | awk '{ print $1 }' )

ph.perfadd "established" "$iEst"
ph.perfadd "listen"      "$iListen"
ph.perfadd "time-wait"   "$iWait"

# --- bye
ph.exit