Re: DHCP timeout is too short for this college network

[José Queiroz <zekkerj gmail com>]

2010/1/22 Daniel Gnoutcheff <daniel gnoutcheff name>:
> From what I've seen, it looks like dhclient already does something similar.
>
> If I put "timeout 45;" in dhclient.conf and then run dhclient on a network
> where no DHCP servers are present (i.e. no OFFERs are received), then
> dhclient does indeed timeout in 45 seconds.
>
> However, as soon as it gets an OFFER, it seems that the 45 second countdown
> stops. dhclient then proceeds to try and get an ACK, and this process seems
> to be subject to a separate (hard coded?) timeout. If that fails, then
> dhclient returns to the DISCOVER stage and once again waits 45 seconds for
> an OFFER.
>
> So the good news is, dhclient is already setup so that it times out
> relatively quickly when DHCP servers are not present, and it's also willing
> to wait longer when dealing with lazy servers.
>
> The bad news is that this behavior is not well documented, and I don't know
> if there are any limits on how many times it will "loop" like this. If I
> were to hit a broken DHCP server that always sent OFFERs but never sent
> ACKs, it's possible that dhclient would never time out. But I'd argue that
> this would be a dhclient bug that may be worth fixing anyway.
>

Maybe this second timeout is defined in the RFCs.