[Nagiosplug-help] How do i check dhcpd running on remote host

[Andreas Ericsson]

Rajendra Adhikari wrote:
> The nagios monitor is 3 hops away from the dhcpd server. In between 
> there are non-cisco routes and they do not support as dhcp relay agent. 


That doesn't matter, since dhcp-relay work on layer 3 (i.e. it can 
handle normal, basic IP routing). What I've been trying to tell you is 
that the check_dhcp I've patched up supports *acting* like a dhcp-relay. 
  This means it can unicast its packets directly to the destination 
address so long as you can reach the dhcp-server through normal IP 
operations. You don't have to have any dhcp-relay hardware for this at all.


> Nagios monitor do not get IP address from dhcp server.
> I have installed the plugin 
> http://oss.op5.se/nagios/op5plugins-2005-09-27.tar.gz.
> #check_dhcp --serverip=192.168.1.2
> Error: Could not bind socket to interface eth0.  Check your privileges...
> 

chown root:root check_dhcp
chmod 4755 check_dhcp

check_dhcp must set up an udp socket at port 53 (or 54), which is < 1024 
and thus protected.

> It is certain that the dhcp request from nagios monitor will never reach 
> the dhcp server as there are routers in between and they do not act as 
> dhcp relay agent.

Read above....

> If its not possible in this scenario, then is there any other way to 
> check if dhcpd is running on the remote host.
> 

It is possible in this scenario.

> regds,
> Rajen.
> 
> 
> 
> 
> 
> Andreas Ericsson wrote:
> 
>> rajendra at subisu.net.np wrote:
>>
>>> I have my client (where nagios is installed) on different subnet than 
>>> that
>>> of the dhcpd server. However, the dhcpd server is reachable. As it is 
>>> not
>>> on the same boradcast domain there is no way the dhcpd server gets the
>>> broadcast request from the client. I guess, it wont work with the 
>>> standard
>>> plugins.
>>
>>
>>
>>
>> No it won't (unless Sean pulled in the dhcp-relay thingie from me). 
>> That's why I suggested trying the check_dhcp plugin from the package 
>> at http://oss.op5.se/nagios since it's supposed to be able to do this 
>> (provided your dhcp-server accepts relayed requests, which I think is 
>> impossible to turn off).
>>
>>
>>> Is anyone checking the dhcp server running on the separate subnet?
>>>
>>
>> We have a customer that does. The patch originally came from them. I 
>> only modified it to make it accept arguments for the dhcp-server and 
>> such.
>>
>>>
>>> regds,
>>> Rajen.
>>>
>>>
>>>> Rajendra Adhikari wrote:
>>>>
>>>>> Can any one suggest how do I check the dhcpd running on the remote 
>>>>> host?
>>>>> I have tried it with the check_dhcp standard plugins, but could not 
>>>>> get
>>>>> any responce.  Is it possible from standard check_dhcp, or do I 
>>>>> need to
>>>>> go for  check by ssh  or some other things. I would be grateful if you
>>>>> kindly suggest me the way to do it or  provide some reference  
>>>>> about it.
>>>>>
>>>>
>>>> DHCP can only be checked for remote hosts (so far). The DHCP client
>>>> sends broadcasts to communicate with the server (it has to, since the
>>>> DHCP server will assign the IP), which means you can't check a DHCP
>>>> server on a different subnet.
>>>>
>>>> I've tried hacking up a patch for that. You can try using the 
>>>> check_dhcp
>>>> found in the plugins-package at http://oss.op5.se/nagios
>>>>
>>>> Read the --help output (or possibly the source-code). I don't remember
>>>> what options you need to specify off-hand.
>>>>
>>>> Oh, and let me know if it works. :)
>>>>
>>>> -- 
>>>> Andreas Ericsson                   andreas.ericsson at op5.se
>>>> OP5 AB                             www.op5.se
>>>> Tel: +46 8-230225                  Fax: +46 8-230231
>>>>
>>>
>>>
>>>
>>>
>>
> 
> 

-- 
Andreas Ericsson                   andreas.ericsson at op5.se
OP5 AB                             www.op5.se
Tel: +46 8-230225                  Fax: +46 8-230231