Need Help DHCP Server

Mon Mar 18 08:59:12 UTC 2013

Hi,

On Mon, 18 Mar 2013, Prabhpal S. Mavi wrote:

> Dear Christian Kratzer,
>
> Thanks for the time for attending to my problem, i am grateful. i am
> running one dhcp daemon. Becasue of vlans, i mentioned multi tenant, i am
> sorry for the word used that may mean something different.
>
> Sir, You seems to be experienced than me but i will able to follow your
> instructions correctly. i am not new to Linux, but it is first time came
> across this complex DHCP implementation, i may ask some silly questions as
> well.
>
> i understand it is difficult to advice if we don't know how is the network
> looks like and how is the flow of data. i spent sometime to make network
> diagram for you to clear understand. Please enclose network diagram
> attached.
>
> Please do not think i want you do everything for me, kindly consider me
> lower level IT person than you, i need your help.
>
> Is it possible to do, what i have shown in diagram?

yes but please keep the mailing list on the replies so others can learn from this too.

In your example your dhcp has interfaces in 192.168.10.0/24, 192.168.20.0/24, etc...

Your clients are in 192.168.11.0/24, 192.168.21.0/24, etc...

To make above setup work add an empty subnet declaration for each of the interfaces your dhcp server has.

 	subnet 192.168.10.0 netmask 255.255.255.0 {
  	}
 	subnet 192.168.20.0 netmask 255.255.255.0 {
  	}
 	subnet 192.168.30.0 netmask 255.255.255.0 {
  	}
 	subnet 192.168.40.0 netmask 255.255.255.0 {
  	}
 	subnet 192.168.50.0 netmask 255.255.255.0 {
  	}

Keep your production subnets as they are:

 	subnet 192.168.11.0 netmask 255.255.255.0 {
 		option routers 192.168.11.1;
 		option subnet-mask 255.255.255.0;
 		option broadcast-address 192.168.11.255;
 		option domain-name-servers 41.211.0.41;
 		option domain-name "teledataict.net";
 		default-lease-time 3600;
 		max-lease-time 7200;
 		range 192.168.11.100 192.168.11.200;
 	}

Once you have above working you might want to get rid of all the vlan interfaces you have on the server.  A single network on the server is enough.

The server sees from which subnet the request is coming from as the relay inserts it's ip address in the giaddr field when relaying the request.

You do not need a one to one mapping of interfaces and subnets.

Just configure 192.168.90.1 for the server ip and have all relays relay to this same address.  Remeber to add the empty subnet for 192.168.90.0/24 when doing so.

Greetings
Christian

>
> Thanks / Regards
> Prabhpal
>
>
>> Hi,
>>
>> On Fri, 15 Mar 2013, Prabhpal S. Mavi wrote:
>>
>>>
>>> Greetings List,
>>>
>>>
>>> someone please help, i have multi tenant DHCP server running on one
>>> Ubuntu
>>> 12.4LTS host. Setup, one physical interface (eth1) there is no ip
>>> address
>>> on physical interface (eth1 using as trunk mode).
>>>
>>> following static ip address are configured on logical interfaces, and
>>> all
>>> five starts DHCP daemons starts up alright and issues ip address as
>>> expected only when the "dhcpd.conf" is as following.
>>
>> Feeding the information between the lines into my glowing crystal ball
>> it seems you are starting multiple dhcpd.
>>
>> There is no need to start multiple dhcpd. One that listens on all of
>> your five interfaces will work just fine.
>>
>>>
>>> vlan10 ineterafce=192.168.10.10/24
>>> vlan20 ineterafce=192.168.20.20/24
>>> vlan30 ineterafce=192.168.30.30/24
>>> vlan40 ineterafce=192.168.40.40/24
>>> vlan50 ineterafce=192.168.50.50/24
>>>
>>> # Vlan 10
>>> subnet 192.168.11.0 netmask 255.255.255.0 {
>>> option routers 192.168.11.1;
>>> option subnet-mask 255.255.255.0;
>>> option broadcast-address 192.168.11.255;
>>> option domain-name-servers 41.211.0.41;
>>> option domain-name "teledataict.net";
>>> default-lease-time 3600;
>>> max-lease-time 7200;
>>> range 192.168.11.100 192.168.11.200;
>>> }
>>>
>>> # Vlan 20
>>> subnet 192.168.21.0 netmask 255.255.255.0 {
>> <snipp/>
>>> }
>>>
>>> # Vlan 30
>>> subnet 192.168.31.0 netmask 255.255.255.0 {
>> <snipp/>
>>> }
>>>
>>>
>>> # Vlan 40
>>> subnet 192.168.41.0 netmask 255.255.255.0 {
>> <snipp/>
>>> }
>>>
>>>
>>> # Vlan 50
>>> subnet 192.168.51.0 netmask 255.255.255.0 {
>> <snipp/>
>>> }
>>>
>>
>> above looks ok to me.
>>
>>> But we have the requirement where i need to issue ip address from the
>>> range that is not configured on the server (request coming through dhcp
>>> relay agent (bootp helper) from remote network) for example. Please mind
>>> that ip address "192.168.61.x" is not configured on any interface of my
>>> DHCP server ("/etc/network/interface"). If i was adding following code
>>> in
>>> to the "dhcpd.conf" daemon fails to start. since this ip range (subnet)
>>> in
>>> not my server, i have to issue these ip to remote client request came
>>> through dhcp relay agent.
>>>
>>> subnet 192.168.61.0 netmask 255.255.255.0 {
>>> option routers 192.168.61.1;
>>> option subnet-mask 255.255.255.0;
>>> option broadcast-address 192.168.61.255;
>>> option domain-name-servers 41.211.0.41;
>>> option domain-name "teledataict.net";
>>> default-lease-time 3600;
>>> max-lease-time 7200;
>>> range 192.168.61.100 192.168.61.200;
>>> }
>>
>> you always need subnet declarations for the interfaces the host is
>> serving.
>>
>> It fully ok to have additional subnet declarations for remote interfaces
>> that you receive requests for from some relay.
>>
>> You just need to add an empty subnet declaration for the interface or
>> interfaces your dhcp is listening on.
>>
>>> But following configuration solved the problem. i as able to issue ip
>>> address for subnet "192.168.61.0" if configuration is like this.
>>>
>>>
>>> subnet 192.168.0.0 netmask 255.255.0.0 {
>>> option routers 192.168.10.10;
>>> option subnet-mask 255.255.255.0;
>>> option broadcast-address 192.168.10.255;
>>> option domain-name-servers 41.211.0.41;
>>> option domain-name "teledataict.com";
>>> default-lease-time 3600;
>>> max-lease-time 7200;
>>> range 192.168.10.100 192.168.10.200;
>>> }
>>>
>>> subnet 192.168.0.0 netmask 255.255.0.0 {
>>> }
>>>
>>> subnet 192.168.0.0 netmask 255.255.0.0 {
>>> }
>>>
>>>
>>> subnet 192.168.0.0 netmask 255.255.0.0 {
>>> }
>>>
>>>
>>> subnet 192.168.0.0 netmask 255.255.0.0 {
>>> }
>>
>> you have five subnet declarations all for the same network. That cannot
>> work.
>>
>> You are propably best of running a single dhcp for all your networks.
>> Make sure
>> you have subnet declarations for all networks your dhcp is listening on
>> including
>> the interface you receive the requests from the relay.
>>
>> Greetings
>> Christian
>>
>> --
>> Christian Kratzer                      CK Software GmbH
>> Email:   ck at cksoft.de                  Wildberger Weg 24/2
>> Phone:   +49 7032 893 997 - 0          D-71126 Gaeufelden
>> Fax:     +49 7032 893 997 - 9          HRB 245288, Amtsgericht Stuttgart
>> Web:     http://www.cksoft.de/         Geschaeftsfuehrer: Christian
>> Kratzer
>>
>
>
>

-- 
Christian Kratzer                      CK Software GmbH
Email:   ck at cksoft.de                  Wildberger Weg 24/2
Phone:   +49 7032 893 997 - 0          D-71126 Gaeufelden
Fax:     +49 7032 893 997 - 9          HRB 245288, Amtsgericht Stuttgart
Web:     http://www.cksoft.de/         Geschaeftsfuehrer: Christian Kratzer