how to ask a dhcp server to respond a petition only if a condition happens

Simon Hobson dhcp1 at
Wed Mar 17 19:14:08 UTC 2010

Lulu GO wrote:

>I couldn't understand from your reply if the classes you define are 
>in the dhcpd.conf, and if that the case I think I can use it for the 
>purpose I need, thanks! I will try it and let you know.

Yes, they are defined in the DHCP config - but you need an identifier 
that will tell you which access point a client is connected to. It is 
probably worth looking in detail at the received packets to determine 

If you can device a test, then the class method would work for you.

>The thing about blocking the clients from the other school or the 
>outdoor clients is, that is not the solution we were asked to do, in 
>fact they want the clients to associate to the optimum server 
>despite where they are.

Sorry if it didn't read correctly, the plan wasn't to block devices 
based on who they are, only on which access point they connect to. As 
in, the DHCP server in school A will not respond (ie ignore, or the 
packet is blocked in the network) to requests from clients in school 

One other thing that comes to mind, many managed switches have some 
form of DHCP filtering. It may be worth looking at the switches in 
use - if they have this, then they could block DHCP requests from 
clients on the other side of the WAN link. This would be configured 
by blocking inbound DHCP on the port to which the WAN link is 

Simon Hobson

WANTED: "Software CD ROM Kit" for Canon CLBP 360-PS printer (Canon 
part no RH6-3612, or possibly RH6-3810, or RH6-3610 might do). I've a 
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This is NOT the same thing as the printer drivers to load on the 
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If anyone knows where I might get hold of one I'd be grateful - 
requests to Canon drew a blank, it's been out of support for years.
Alternatively, if anyone has one of these and would let me image 
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