Network, routers, DHCP and PXE

[Manolis Kiagias]

Svein Halvor Halvorsen wrote:
> Manolis Kiagias wrote:
>   
>>> Yeah, but even though the router has customizable values for this
>>> range, and issues a warning when i try to change them, it still
>>> doesn't change them when I click "yes" on the warning. It is
>>> pre-configured to 10.0.0.2-10.0.0.253
>>>
>>> I could of course use 10.0.0.254 for my static ip, but my room mate
>>> also wants a static address.
>>>       
>> What are you trying to set it at? I would just lower the 253 value, so I 
>> could use the upper end for my static addresses. If you try to set it to 
>> a subnet outside it's own address, it will definitely not accept it.
>>     
>
> I managed to change the router ip address to 10.0.0.1/23 and just
> keep the default dhcp address space as 10.0.0.2-10.0.0.253. Now I
> seem to be able to use 10.0.1.1/24 for my own private use.
>
> (I don't think I really know what I'm doing here, but it works!)
>   

Well, a netmask of 255.255.254.0 should give you 10.0.0.1 to 10.0.1.254 
host addresses.
10.0.1.1 is within range, it should work.
>
>   
>> Well problem is, a netmask of 255.255.255.0 means only the last octet 
>> can be used for hosts. Your DHCP server is already assigning addresses 
>> from this space.
>>     
>
> Well, I changed it to 255.255.254.0 (0xfffffe00) but kept the dhcp
> range as it was.
>
>
>   

The DHCP range you are assigning is a subset of what you allowed with 
the netmask, thus it is valid.

>>> So as long as I make my own DHCP server act the same way as the
>>> router one, I should be fine? NAT and all will work?
>>>       
>> Yes. As long as the clients have a valid DNS to ask, and a valid gateway 
>> to send their packets, everything will work properly. If you come to 
>> think about it, you are already doing this on the system with the static 
>> configuration.
>>     
>
> Ok, I will look into this.
>
> Also, looking through the telnet interface options (which are far
> more than the web interface gives), I see that I can add "dhch
> server option templates", "dhcp server option instances" and that I
> can assign such an instance to the "dhcp server pool options".
>   

Ah, yes completely forgot the speedtouch has a telnet interface as well. 
I messed with it a few times myself, mostly for fun ;)

> This uses a different config scheme than the isc dhcp server config
> files, though. And it seems I need to create a template before I can
> create an instance. The template takes a name and an option id as
> paramters. The instance, then takes a name, a template, and a value
> as mandatory paramters. Also enterprice number, suboption number,
> and more.
>
> How does the "filename", "next-server", etc map to option ids? Are
> these isomorphic, or do I get this completely wrong?
>
> Does this make any sense to you, or anyone else here? Should I try
> to make the router DHCP server serve the right options, or would you
> go the isc dhcp route?
>
>
> Thank you very much for your help so far!
>
>
> 	sv.
>
>   


I have only done PXE with Windows servers, and it has been quite some 
time - cannot remember the details.
I certainly would not advise you to use the router for this - even if it 
is possible it has several drawbacks.

- You will, sooner or later, change the router and your new one may not 
have the capability
- You will spend a probably unreasonable amount of time trying to make 
it work - and it may not even succeed
- Learning how to perform this on FreeBSD will help you apply it in many 
other situations.

I would definitely go the isc-dhcp route.