Fwd: Re[4]: How to - DHCP Relay and Server on same machine (FreeBSD)

[test24]

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


In my case dhcp relay MUST listen one port (standart 67/68 for clients side) and send requests to NEXT server on OTHER port.
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.

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.

Second reason - my machine acts as router and vlans back end. Than option 82 must be added on this machine ().
And on this machine dhcpd must say replies for unknown client MACs but known client vlans






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