How do I point a client to a unicast DHCP server?

[Alan DeKok]

On Nov 11, 2021, at 5:50 AM, Selahattin CILEK <selahattin_cilek at hotmail.com> wrote:
> 
> I am using FreeRADIUS 3.0.23 to deliver services on pfSense 2.5.2 ( FreeBSD 12.2).
> 
> Because of some rogue users, I have to issue each device a static IP address. I know I can do this thanks to the *dhcp_sqlippool* mod, but reading the *dhcp* site provided by the default install, I ran into this sentence:
> 
> FreeBSD does *not* support binding sockets to interfaces. ...
> 
> 
> I know a solution is suggested in the same paragraph, but I will do that only as a last resort.
> 
> 
> I went ahead and added *dhcp* to *sites-enabled* anyway and then ran FreeRADIUS in debug mode (radiusd -X). It was a success:

  That's good.

> So I see I can still use the DHCP functionality, but with a caveat: I must somehow get the client to ask for an IP address directly from the router's LAN IP address.
> 
> So my question is: Can I somehow get the clients to use unicast DHCP? In other words, is there some sort of RADIUS attribute I can inject into the authentication reply so that it will know where to get its IP from?

  You configure the switch to act as a DHCP gateway.  It will take all DHCP packets from the client, and unicast them to the DHCP servers IP address.

  See your switch configuration for how to do this.

  Alan DeKok.