Re[5]: How to - DHCP Relay and Server on same machine (FreeBSD)

test24 test24 at mail.ru
Wed Jun 17 18:57:38 UTC 2015


 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.

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.isc.org/pipermail/dhcp-users/attachments/20150617/181edfd8/attachment.html>


More information about the dhcp-users mailing list