#!/bin/sh -u LastCheckFile=/var/cache/nagios/check_dyndnsip.last CurlHttpProxy= if [[ "$1" == "" ]] then text="Usage: $0 dyndns-host-to-check [update-credentials]" rc=3 else rc=-1 text= diags= DdnsHost=$1 if [[ $# -ge 2 ]] then DynDnsCredentials=$2 diags="$diags [update:yes]" else DynDnsCredentials= fi # # Since DynDNS says, we should not check more often than every # ten minutes, the result of the last check is remembered and # re-used, if younger! # if [[ -r $LastCheckFile ]] then Now=`date "+%s"` LastChecked=`stat -c "%Y" $LastCheckFile` LastCheckAge=$(( $Now - $LastChecked )) diags="$diags [cache: ${LastCheckAge}s]" else LastCheckAge=999999999 diags="$diags [cache: no file]" fi # # Now determine our external address. We ask checkip.dyndns.org # what address it sees in our request and parse the resulting # numeric address from the HTML output... # if [[ $LastCheckAge -ge 600 ]] then diags="$diags [query: yes]" CurlResult=`curl --proxy "$CurlHttpProxy" -s -S checkip.dyndns.org 2>&1` ExpectedIP=`expr "$CurlResult" : '^.*Current IP Address: $[0-9][0-9]*\.[0-9][0-9]*\.[0-9][0-9]*\.[0-9][0-9]*$.*$'` if [[ $? -ne 0 ]] then text="Cannot parse result from checkip.dyndns.org: $CurlResult" rc=2 else rm -f $LastCheckFile echo >$LastCheckFile "$ExpectedIP" fi else diags="$diags [query: no]" ExpectedIP=`cat $LastCheckFile` fi # # Next, get the IP address currently known to DNS (but # only, if we're still in the game!) There might be better # ways to do that, but it works. # if [[ $rc -le 0 ]] then HostResult=`host $DdnsHost` if [[ $? -eq 0 ]] then DefinedIP=`expr "$HostResult" : '.* has address $[0-9][0-9]*\.[0-9][0-9]*\.[0-9][0-9]*\.[0-9][0-9]*$$'` if [[ $? -ne 0 ]] then text="Address not found in output from host command: $HostResult" rc=2 fi else text="Could not resolve current address of host '$DdnsHost': $HostResult" rc=2 fi fi # # OK, we have the expected and the defined IP addresses now. # So let's check, whether they match. # if [[ $rc -le 0 ]] then if [[ "$ExpectedIP" == "$DefinedIP" ]] then text="$DdnsHost has address $ExpectedIP" rc=0 else # # OOPS! The external address is not what we expected! Of course, # we could just return a CRITICAL condition, but let's play clever! # Why not try and currect the problem right away? This function is # only available, however, if credentials are given! # if [[ "$DynDnsCredentials" != "" ]] then Query="http://$DynDnsCredentials@members.dyndns.org/nic/update?system=dyndns&hostname=$DdnsHost&myip=$ExpectedIP&wildcard=on&offline=no" Result=`curl --connect-timeout 60 --proxy "$CurlHttpProxy" -s -S "$Query" 2>&1` if [[ $? -eq 0 ]] then if expr "$Result" : "^good $ExpectedIP" >/dev/null then diag="$diag [update: $Result]" text="$DdnsHost has been updated to $ExpectedIP (was: $DefinedIP)" rc=1 else text="Update of $DdnsHost from: $DefinedIP to: $ExpectedIP failed: $Result" rc=2 fi else text="Update of $DdnsHost failed in curl: $Result" rc=2 fi else text="$DdnsHost in DNS is: $DefinedIP, but should have: $ExpectedIP" rc=2 fi fi fi fi # # Finally, prepare the result for Nagios. The status strings # are properly prepended and given back... # case $rc in 0) text="OK - $text" ;; 1) text="WARNING - $text" ;; 2) text="CRITICAL - $text" ;; 3) text="UNKNOWN - $text" ;; *) text="INTERNAL ERROR: Status code not properly set!" rc=3 ;; esac echo "$text $diags" exit $rc