[GRLUG] DD-WRT DHCP/IP address problem

[John-Thomas Richards]

On Tue, Apr 05, 2016 at 08:56:33PM -0400, Mark Farver wrote:
> On Tue, Apr 5, 2016 at 5:00 PM, John-Thomas Richards <jtr at jrichards.org> wrote:
> > I have a Buffalo router running DD-WRT. It has a virtual wireless
> > interface for guests. It is configured to issue IP addresses like
> > 192.168.11.x. It is issuing addresses with the wrong third number
> > (192.168.1.x instead of 192.168.11.x). This appears to be a problem with
> > multiple android devices. Restarting the router does not fix it.
> > Restarting the Android WiFi service and even the device does not fix it.
> > I can, sometimes, get a device to obtain a correct IP by connecting to
> > the primary network and then back to the guest network.  This is new
> > behavior in the last few weeks. The router is a few months old and has
> > been working just fine otherwise. Any ideas why it's doing this?
> > 
> Seems odd that a "guest" network would be issuing addresses that have
> the same subnet as the primary network.  It would make it a lot more
> complicated to firewall the guests off from the main network.  Are you
> sure that giving guests IPs from a different netblock isn't the
> intended behavior?

DD-WRT has an option for "AP Isolation." According to the documentation
(keeping in mind that I am not a network guy of any sort), AP Isolation
prevents wireless clients from accessing other wireless clients. This is
from the actual docs for it:

*****

        When this feature is enabled the software builds a logical rule
        (or filter) for these MAC addresses and ports that says: "If the
        packet originates on the wireless port, it can only send and
        receive packets that are destined or originate from the router
        port or ethernet switch port."

        Not a very complex rule, but one which totally prevents wireless
        client to client traffic. Not even broadcasts will go from
        wireless client to client.

****

There is not an option for configuring the range of IP addresses for the
guest network with a different subnet.
-- 
J-T
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Life is short; think quickly.