Can we make NM automatically handle the need for proxy arp?

["Miles Lane" <miles lane gmail com>]

Hello,

Here are extracts from a dialog between myself and Ted Lemon.
I hope that NM can be made to automatically set up wifi connections
that are handled by Windows.  Currently, I sometimes encounter
failures.

Ted isn't subscribed to the list.

---------------

ME:

I often find that in hotels, setting up a wifi connection is a
two-stage process under Windows XP.  First, I must connect to the
access point and then, when I open a web browser, I am redirected to a
log-in/sign-up screen.  Once I have paid for access, my network
requests start going through.

I often find that something breaks down in this process when I am
running Linux.  Tonight I have been trying to get a wifi connection
working at a Shilo Inn Hotel, which provides free wireless, but still
redirects my first browser connection attempt to an agreement page.
Unfortunately, I had to boot Windows to get to the page.  Also, when I
try to use NetworkManager in Ubuntu 6.06.1 LTS (very current NM code),
I get:

Internet Systems Consortium DHCP Client V3.0.3
Copyright 2004-2005 Internet Systems Consortium.
All rights reserved.
For info, please visit http://www.isc.org/products/DHCP

Listening on LPF/eth1/00:12:f0:5e:db:2f
Sending on   LPF/eth1/00:12:f0:5e:db:2f
Sending on   Socket/fallback
DHCPREQUEST on eth1 to 255.255.255.255 port 67
DHCPACK from 192.168.21.254
SIOCADDRT: Network is unreachable
bound to 192.168.21.10 -- renewal in 6356 seconds.

I have:   network-manager     0.6.2-0ubuntu7

After hunting about on the web, I eventually found the suggestion that
I needed to use "route" to add a default gateway.  After some
experimentation, I found that:

    route add default gw 192.168.21.254

got my connection working.

----------------------------

TED:

> lease {
>  interface "eth1";
>  fixed-address 192.168.21.10;
>  option subnet-mask 255.255.255.0;
>  option routers 205.171.3.65;
>  option dhcp-lease-time 14400;
>  option dhcp-message-type 5;
>  option dhcp-server-identifier 192.168.21.254;
>  option domain-name-servers 205.171.3.65;
>  renew 6 2006/8/26 07:05:42;
>  rebind 6 2006/8/26 08:49:46;
>  expire 6 2006/8/26 09:19:46;
> }

Now this lease you got about three minutes after the previous lease
died.   Notice that the IP address in the routers option is on a
different subnet than the IP address in the fixed-address option.
This is what's causing the SIOCADDRT error.

So I think this confirms my previous theory.   The reason your WinXP
machine succeeds in using the network is because it's using something
other than DHCP to get routing working.   And the reason your linux
box fails is that it's relying entirely on DHCP.   So to fix the
problem, we probably need to dig deeper, which could be a problem if
you're not still at the Shiloh Inn.

If you are still there, can you get your system booted up into
Windows, start a terminal window, and type "ipconfig/all" and cut-and-
paste the output to me?

-------------------------

ME:

# ipconfig/all

Windows IP Configuration

      Host Name . . . . . . . . . . . . : lowly
      Primary Dns Suffix  . . . . . . . :
      Node Type . . . . . . . . . . . . : Hybrid
      IP Routing Enabled. . . . . . . . : Yes
      WINS Proxy Enabled. . . . . . . . : No

Ethernet adapter IPW2200:

      Connection-specific DNS Suffix  . :
      Description . . . . . . . . . . . : Intel(R) PRO/Wireless
2200BG Network Connection
      Physical Address. . . . . . . . . : 00-12-F0-5E-DB-2F
      Dhcp Enabled. . . . . . . . . . . : Yes
      Autoconfiguration Enabled . . . . : Yes
      IP Address. . . . . . . . . . . . : 192.168.21.4
      Subnet Mask . . . . . . . . . . . : 255.255.255.0
      Default Gateway . . . . . . . . . : 205.171.3.65
      DHCP Server . . . . . . . . . . . : 192.168.21.254
      DNS Servers . . . . . . . . . . . : 205.171.3.65
      Lease Obtained. . . . . . . . . . : Sunday, August 27, 2006 8:06:49 AM
      Lease Expires . . . . . . . . . . : Sunday, August 27, 2006 12:06:49 PM

Ethernet adapter Local Area Connection:

      Media State . . . . . . . . . . . : Media disconnected
      Description . . . . . . . . . . . : Realtek RTL8139/810x
Family Fast Ethernet NIC
      Physical Address. . . . . . . . . : 00-C0-9F-95-18-1B

-----------------------

TED:

Yup, the only way that's working is with proxy ARP.   And Linux isn't
trying to ARP for the router, because it's not on the right subnet.
The sad fact is that what's really going on here is that Windows is
doing something it shouldn't be doing to work around a misconfigured
DHCP server, and so the guys running the DHCP server think the DHCP
server is configured just fine.   :'/

------------------------

Anyhow, I would love to see us handle this "broken" router configuration,
since this sort of failure comes up for me often when I am trying to access
hotel WIFI networks.

Thanks,
        Miles