Problem with chillispot and dhcp relay

[Giosue Pacifico]

Hi,
with Cisco WLC controller the dynamic interface bound to CoovaChilli
vlan is the real destination for client dhcp discovery and dhcp relay
agent as it acts as a L2 filter. If you use chilli as "Primary DHCP
Server" [read ip helper-address] it won't work because chilli doesn't
understand unicast request. You ought to setup an external DHCP server
with scope = "dynip net" & "statip net" in chilli.conf and allow
communication toward this server with "allowed udp:[external dhcp
server IP or fqdn]:67" in the same file.
To reach the dhcp server assign an IP outside the scope to "dhcpif"
(usually eth1).

client--[dhcp discovery]--->WLC-DYN-IF 172.18.183.3--->(bypasses)
CHILLI tun0 172.18.183.1/ eth1 172.18.183.2 --->ext DHCP Server
x.y.w.z

Hope I've been useful,
ciao
Giosuè

On 9/4/07, Lai Zit Seng <lzs at pobox.com> wrote:
> Hi,
>
> I am trying out chillispot-1.0-coova.7. It works great with my wired
> network clients. But when I start to move on to wireless, I have a problem.
>
> Although the chillispot logs say addresses are being assigned to
> clients, the client never get any IP address. E.g. I see in my log:
>
> Sep  4 13:58:55 faber chillispot[26842]: chilli.c: 2620: Client
> MAC=00-13-CE-8B-21-9C assigned IP 172.18.183.12
>
> But actually the client didn't get any IP. From tcpdumping on the
> chillispot machine, I realize that there is a dhcp relay agent making
> forwarding DHCP for the actual wireless clients. The dhcp relay unicasts
> the DHCP packets to chillispot, but chillispot replies to the broadcast
> IP. Perhaps something has gone wrong here?
>
> Ok, why is there a dhcp relay agent? My wireless network makes use of
> Cisco Wireless LAN Controller. The controller insists on relaying all
> DHCP on behalf of the clients, I suppose in order to keep track of DHCP
> requests and IP assignments, to make sure clients don't "cheat".
>
> Anything I can do with chillispot to accommodate the dhcp relay agent?
>
> Regards,
>
> .lzs
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: chilli-unsubscribe at coova.org
> For additional commands, e-mail: chilli-help at coova.org
> Wiki: http://coova.org/wiki/index.php/CoovaChilli
> Forum: http://coova.org/phpBB3/viewforum.php?f=4
>
>