check_arping

#!/usr/bin/env python3
#-------------------------------------------------------------------------------

import argparse
import sys
import os
import subprocess

#-------------------------------------------------------------------------------

_candebug = False
def setcandebug(value):
    global _candebug
    _candebug = value
def candebug():
    global _candebug
    return _candebug

def infomsg(msg):
    if candebug() == True:
        print(msg, flush=True)

def exitnagios(status,message):
    if status=="OK":
        exitcode = 0
    elif status=="WARNING":
        exitcode = 1
    elif status=="CRITICAL":
        exitcode = 2
    elif status=="UNKNOWN":
        exitcode = 3
    else:
        exitcode = 4
    print(status+": "+message, flush=True)
    sys.exit(exitcode)

#-------------------------------------------------------------------------------

def doarpingcall(hostname,packets,timeout):
    cmdline = ["/usr/sbin/arping","-C",str(packets),"-w",str(timeout),hostname]
    completedproc = subprocess.run(cmdline,capture_output=True)
    output = completedproc.stdout.decode("utf-8")
    errors = completedproc.stderr.decode("utf-8")
    response = completedproc.returncode

    infomsg(output)

    #and then check the response...
    if response == 0:
        alllines = output.splitlines()

        allmacs = []
        for line in alllines:
            if " bytes from " in line:
                parts = line.split()
                mac = parts[3]
                if mac not in allmacs:
                    allmacs.append(mac)
        infomsg(allmacs)

        if len(allmacs)==1:
            linems = alllines[-1]
            linepercent = alllines[-2]
            avgms = float(linems.split("=")[1].strip().split()[0].split("/")[1])
            percent = float(linepercent.split(",")[2].strip().split()[0].replace("%",""))

            exitnagios("OK",hostname+" is respoding to ARP | average="+str(avgms)+" percent="+str(percent))
        else:
            exitnagios("CRITICAL",hostname+" has several MACs responding to ARP "+str(allmacs)+" | average=0 percent=0")
    else:
        exitnagios("CRITICAL",hostname+" is not responding to ARP | average=0 percent=0")

#-------------------------------------------------------------------------------

#collect arguments
def parse_args():
    parser = argparse.ArgumentParser()
    parser.add_argument("-H", "--hostname",          action="store",                                                                              help="target IP or hostname")
    parser.add_argument("-p", "--packets",           action="store",       type=int,                default=5,                                    help="number of pings")
    parser.add_argument("-t", "--timeout",           action="store",       type=int,                default=10,                                   help="timeout")
    parser.add_argument("-®", "--debug",             action="store_true",  dest="debug",            default=False,                                help="be more verbose")
    args = parser.parse_args()

    return args

def main():
    args = parse_args()
    setcandebug(args.debug)

    if not args.hostname:
        exitnagios("CRITICAL","Must give a hostname.")

    doarpingcall(args.hostname,args.packets,args.timeout)

if __name__ == "__main__":
    main()

#-------------------------------------------------------------------------------