check_noroutehostgateway

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

import sys
import os
import argparse
import subprocess
import concurrent.futures
import ipaddress

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

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

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 checkifaddress(test):
    converted = None
    try:
        converted = ipaddress.ip_address(test)
    except:
        pass
    return (converted != None)

def donoroutehostgatewaycall(protocol,whitelist):
    cmdline = ["/usr/bin/ip",protocol,"route"]
    infomsg(cmdline)
    completedproc = subprocess.run(cmdline,capture_output=True)
    output = completedproc.stdout.decode("utf-8")
    errors = completedproc.stderr.decode("utf-8")
    exitcode = completedproc.returncode
    if exitcode!=0:
        return [protocol+": cannot read routes table"]

    exclusion = []
    for item in whitelist.lower().split(","):
        exclusion.append(item.split("/"))

    errormsgs = []
    for line in output.strip().splitlines():
        if line.startswith(" ") == False:
            parts = line.split()
            if (len(parts)>0) and (checkifaddress(parts[0]) == True):
                infomsg("found address: "+str(parts))
                if parts[len(parts)-1].lower() != "linkdown":
                    infomsg("found candidate: "+str(parts))
                    if len(parts)>1 and parts[1].lower() == "via":
                        infomsg("checking if this is an exception: "+str(parts))
                        exception = False
                        for item in exclusion:
                            if len(item)>0 and item[0]==parts[0]:
                                if len(item)>1:
                                    if item[1]==parts[2]:
                                        if len(item)>2:
                                            if item[2]==parts[4]:
                                                exception = True
                                        else:
                                            exception = True
                                else:
                                    exception = True
                        if exception == False:
                            errormsgs.append(protocol+": found UGH route "+parts[0]+"/"+parts[2]+"/"+parts[4])

    return errormsgs


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

def parse_args():
    parser = argparse.ArgumentParser()
    parser.add_argument("-l", "--whitelist",         action="store",       dest="whitelist",        default="",                                   help="routes to whitelist")
    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)

    errormsgs = []
    errormsgs = errormsgs + donoroutehostgatewaycall("-4",args.whitelist)
    errormsgs = errormsgs + donoroutehostgatewaycall("-6",args.whitelist)

    if len(errormsgs)==0:
        exitnagios("OK","routes table looks normal")
    else:
        exitnagios("CRITICAL",str(errormsgs))

if __name__ == "__main__":
    main()

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