How to - DHCP Relay and Server on same machine (FreeBSD)

[Glenn Satchell]

Can you run a virtual machine on this server and have the dhcp daemon on
that? It only needs a single IP address as the relay will forward all
traffic to it.

A little more work to set up and manage, but it would still satisfy your
requirements of no more physical servers and allow you to run the standard
dhcp relay and daemon packages.

regards,
-glenn

On Thu, June 18, 2015 4:57 am, test24 wrote:
>  Sorry for my mail client - it send from russian resource with russian
> incorrect text injection.
>
>>Firstly, could you please fix your email client and get it to quote text
>> properly !
>
> May be it is incorrect question, but who write/rewrite/ make patches to
> ISC DHCP Relay code?
>
> Generally dhcprelay - not very difficult port forward tool with dhcp's
> specific ports and broadcast etc. mechanisms.
> I do not want use second machine, because of care for the environment
> named 'green technology' and I know lot
> of situations when for the dhcp relay's purposes is allocated a separate
> machine with it wattage use.
>
> Second reason to ask to make an different port forward option for Relay -
> it is a most beautiful opportunity of realization dhcp server and
> relay on same machine because of higher interconnect speed (no crosslan
> traffic with its latency, etc.)
>
> And better think - make the product named such as DHCPDRC
> (Daemon+Relay+Client) - ALL in one code cake - with flexible options for
> its needs.
>
> Thanks a lot.
>
> test24 <test24 at mail.ru> wrote:
>
>>  Simon Hobson WROTE
>>>> test24 <test24 at mail.ru
>>> > wrote:
>>>>> >
>>>  man dhcp relay says:
>>>>> >>
>>>  -p PORT
>>>>> >
>>>                Listen  and  transmit  on  port PORT.  This is mostly
>>> useful for
>>>>> >
>>>                debugging purposes.  Default is port  67  for
>>> DHCPv4/BOOTP
>>>>>>> That changes the port the relay agent uses - but **NOT** the port
>>>>>>> it assumes the server is using. Checking the man page I see nothing
>>>>>>> to suggest it can talk to a server via a non-standard port - you
>>>>>>> could try "nnn.nnn.nnn.nnn:77" for server IP, but I suspect that's
>>>>>>> not implemented.
>>>>> If not, I imagine it might be "relatively" simple to edit the code
>>>>> and hard code a different server port to use.
>
>
>> For dhcp relay next server is written in rc.conf as the
>>> dhcrelay_servers="10.10.10.1"         # v4 dhcrelay server(s)
>>> and option -P says ONLY ! one port - for clients and for next server
>>> This port is the same for clients and for next server
>
> You've already said that - we've seen it
>
>> In my case dhcp relay MUST listen one port (standart 67/68 for clients
>> side) and send requests to NEXT server on OTHER port.
>
> You've already said that - it's been pointed out that it probably can't do
> it without editing the code.
> I haven't looked at the code, but I suspect there's a constant defined
> which is used as the destination port for packets sent to the server.
> Changing this is likely to do what you want.
> More elegantly, allowing the server to be specified as "IP:Port" (if it's
> not already) would be even better and would allow what you want from the
> command line without any editing or compiling.
>
>> It is one the SAME machine, than I can not say ! dhcpD ! listen 67 port
>> too. And as a result - dhcpd server not see requests on 77 port because
>> dhcp relay uses only ONE port
>> for clients side and for servers side.
>
> Yes, I got that first time around.
> Though actually it is not correct. It's not because the Relay agent only
> uses one port, it's because the relay agent doesn't appear to have a
> facility to talk to the server running on a non-standard port.
>
>> It is generally unneded if the relay and server placed on different
>> machines, but if machine is same - it is actual needed feature...
>> because i want to add option 82 packets
>> by relay and send replies on this requests by dhcpd server without using
>> second machine.
>
> Yes, and I got that first time around as well.
>
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