DHCP an NAT

Nathan Burgener nathan.burgener at stud.hslu.ch
Tue Jul 15 12:19:32 UTC 2008


I use the DHCP Server V3.0.6 and when I type next-server I get an  
error message. Should I update the server?


Am 15.07.2008 um 14:13 schrieb Anton Lundin:

> On 15 July, 2008 - Nathan Burgener wrote:
>
>>
>> Unfortunately I need the NAT.
>> So there is no possibility to configure the server, that it doesn't
>> answer to 192.168.3.1 but on 172.18.1.1 ?
>>
>> I have another idea. I can install the DHCP server in the same  
>> network,
>> where the client is. But I must configure the server with special
>> options, because the client will boot an image from the TFTP in  
>> network
>> A.
>> I know, how I can configure the filename. But how can I configure,  
>> that
>> the filename is not on the DHCP server, but on another server?
>>
>
> Read up on the opts server-name next-server.
>
> server-name is just the symbolic name of the server, and next-server  
> is
> what server to tftp from.
>
> I have seen that not all pxe-roms i honer the next-server option...
>
>
> //Anton
>
>
>
>>
>> Am 15.07.2008 um 13:27 schrieb Simon Hobson:
>>
>>>
>>> At 12:53 +0200 15/7/08, Nathan Burgener wrote:
>>>> Hello
>>>>
>>>> I have 2 networks, which are connected over a VPN. In the network  
>>>> A,
>>>> there is a DHCP server.
>>>> In network B I have the client. But all client address from source
>>>> 192.168.3.x get a IP from network 172.18.1.x with NAT and then the
>>>> traffic goes through the VPN tunnel.
>>>> On the router in network B I have an ip helper-address to the DHCP
>>>> server.
>>>>
>>>> Now the server gets the Discover from the client with the following
>>>> informations:
>>>> Source IP 172.168.1.1
>>>> Destination: Address from DHCP server
>>>> Relay Agent IP Address: 192.168.3.1
>>>>
>>>> The DHCP server will now send back the offer. But the servers sends
>>>> it to 192.168.3.1 and not to the address 172.168.1.1
>>>> How can I change that?
>>>
>>> Quick answer: Fix your network !
>>> NAT == broken<period> and DHCP will not work in this setup.
>>>
>>> You might be able to work around part of it by adding appropriate
>>> routing and/or nat rules to get the packets back to the relay agent,
>>> or by being creative with shared-network, but then the clients will
>>> not be able to renew their leases later and things will still break.
>>>
>>> Can you remove the nat and make traffic routable between the server
>>> subnet and the 192.163.3.x subnet ?
>>>
>>>
>>
>
> -- 
> Anton Lundin	+46702-161604



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