Reply to remote unicast DHCP requests

Simon Hobson dhcp1 at
Tue May 3 14:40:29 UTC 2011

Paúl Ortiz Imedio wrote:

>  >When you say the server is not responding - 
>does it log the request ? Does it
>>log that it's replying ? Does it have a route to the client's network ?
>Server logs the request, but it does not answer:
>DHCPREQUEST for from 
>XX:YY:ZZ:XX:YY:ZZ via eth0: ignored (not 
>There is no routing problem and it receives the request from the client. The
>problem is that the server interface where it receives the request is not
>attached to any shared network. The server finds the valid lease and the
>configured subnet for ciaddr, but the lack of giaddr makes it ignore the
>request. If I configured the server to be authoritative, it would send a
>DHCPNAK (that is not a solution). That is why I started looking at the code
>for an explanation and I found what I have detailed in my first post.

In that case, your setup is operating correctly - 
it is your expectations that are wrong !
You could have saved a lot of effort by asking 
earlier, and mentioning the authoritative/DHCPNAK 
element to the story.

If setting the server as authoritative results in 
it DHCPNAKing the request, then the requested 
address is not valid according to the DHCP server 
setup. Setting the server to non-authoritative 
results in it simply ignoring the invalid request 
- by design.

So you need to determine why the server believes 
the requested address to be invalid.

Simon Hobson

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author Gladys Hobson. Novels - poetry - short stories - ideal as
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