broadcast problems with dhcpd on bridge interfaces?
Sun May 11 02:55:53 PDT 2003
I'm seeing a fairly odd problem with a wisp-dist (2.4.20 / install on a
Soekris 4521 with a NetGate NL-2511 Prism2.5 card. I have dhcpd running
on a bridge interface using eth1 and netcs1. I have two OS X machines
which obtain leases normally and a WET11 connected to a W2k desktop,
neither of which can obtain a lease.
The entire config is pretty vanilla - public eth0 NATed for br0
clients, no firewall rules, wireless card is a prism2.5 in HostAP mode,
WEP isn't involved, etc. The only change from the default wisp-dist was
the replacement of pump with dhclient to avoid pump's client ip
dhcpd is clearly seeing the requests:
> May 10 22:29:52 192.168.1.1 dhcpd: DHCPDISCOVER from 00:06:25:02:a4:54
> via br0
> May 10 22:29:53 192.168.1.1 dhcpd: DHCPOFFER on 192.168.1.4 to
> 00:06:25:02:a4:54 via br0
That offer is never received by the client. tcpdump on br0 (or netcs1)
shows no sign of any reply being sent by dhcpd but that's apparently a
bug as it never shows a reply for the working hosts, either. tcpdump
behind the WET11 shows requests being sent without reply from the
The one interesting thing in syslog is this message:
> AP: packet to non-associated STA <ethernet MAC of machine behind WET11>
Everything works with static IP assignments; I can even send a
broadcast ping from an autoconfigured (169.254) address and get replies
from the other clients.
My current theory is that some interaction between the bridging code
and broadcast is causing the hostap driver to discard broadcast
packets, which would explain why unicast traffic is unaffected. What I
don't understand is why this bug would only affect the WET11 - not
forwarding packets to a machine which isn't known to be on the wireless
network fits; refusing to send broadcast packets to another wireless
client does not. There's also something odd about OS X being unaffected
but I haven't compared the raw frames between the working and
non-working systems yet - since the same machine which works over
802.11b will also fail over ethernet behind the WET11 it doesn't look
like a difference between the DHCP clients.
I've spent a fair amount of quality time with Google and haven't turned
up any solutions, although I've found a few people asking about what
sounds like the same problem. Has anyone found a fix?
"prism2_param netcs1 wds_type" looked interesting based on the
description ("use broadcast RA (WDS frame destination) for broadcast
and multicast frames") and the default having this disabled but it
returns an error ("Interface doesn't accept private ioctl...") for any
of the values listed. Based on the STA firmware version in dmesg
(v1.4.9) it sounds like I need new firmware to have this work using the
standard mode (4) - unfortunately, NetGate only has 1.4.9 up on their
Does it reasonable to expect a newer revision to fix this problem or am
I chasing the wrong option?
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