obliquity
‘problems for which the best solution turns out to be an indirect way’
‘problems for which the best solution turns out to be an indirect way’
Originally posted October 2008
After a cheap and sustainable way to get wireless in the house, I reused an ADSL BT wireless router that had been provided to a business and was no longer needed.
14.9.09: this article is about adding a wireless access point to an existing physical network, ie bridging from ethernet to WIFI. If you want to use it to supplement an existing wireless LAN, this article is not likely to help much. The link at the bottom of the page might help.
You’ll need to get onto the web interfaces.
You may need to work through the steps below to get onto the web interface in the first place. Try http://home/managment if its your internet gateway.
Once you’ve found the web front end, if you go to the /managment page (yep, misspelt) you’ll find lots of diagnostics and configuration options; such as static DNS, syslog forwarding etc.
Its in the ‘resets’ page under ‘troubleshooting’ on the managment (sic) page.
Plug in a laptop (or whatever) to one of the ethernet ports and it’ll be issued an address on the default network for the BT device. Web administration is achieved by browsing to it.
On your laptop, find out the BT device’s address with the command netstat -rn – it should be the only non-zero address in the ‘gateway’ column.
With DHCP enabled on the BT device, it’ll assume that it provides internet access and advertise itself to those machines as the gateway. That won’t work; for the purposes of having dumb wireless bridge, all the automatic features need to be disabled, and it needs to be told to use your network as well. (in my case, the purple one on my smoothwall)
“local network/advanced settings” page
“Private network” select “configure manually”
Give it a fixed IP on the LAN so it can be administered. Something not assigned already, and outside of the DHCP range. Set the subnet mask. Once set up and tested, you could tell the BT router that its IP address is anything: it’ll simply provide the physical layer and then the clients will broadcast for an IP. The BT device doesn’t care that they’re getting valid IPs and it doesn’t.
But it’d be a pain to reconfigure wireless – short of isolating it and messing around with static IPs, you’d have to isolate the BT device, to reset it factory settings every time you wanted to access the web admin page.
We need to leave DHCP on for the moment. So, change it, if required, to a range on the same network as the hub, excluding the hub’s address.
It’ll then reset.
You’ll probably need hotplug the laptop network connection to trigger a new DHCP request.
“Local Network” page. Select “Edit settings” under “Wireless Settings.” On the wireless screen, set up the accesspoint as you see fit. Personally, I turn off broadcast and wep (13 character password) is the most reliable option for linux clients. Not very secure, but then I consider all wireless to be fundamentally insecure, and its firewalled from my main network.
Test it. Disconnect the laptop and connect via wireless.
The BT devices has four ethernet ports for clients: on one ethernet port is the ‘purple’ interface of my smoothwall firewall/router.
The purpose of this purple network is to segregate insecure wireless from far more secure hard wired (‘green’). Purple has its own IP address range and is serviced with DHCP and dished out with a gateway for internet access. Traffic isn’t routed to the green network. (Traffic is supposed to route from green to purple, but doesn’t on my machine. Which is a pain!)
On a more conventional home setup, the router providing internet access probably doesn’t have a dedicated wireless subnet. So, I’m assuming you’re just connecting it onto your main LAN, so you have a switch or hub and want to provide wireless access to the existing network.
Both the BT device and your network device expect computers to be plugged in, not other network devices. So, you’ll need either [a] cross-over cable [b] a ‘link’ socket on the device (used for daisy chaining switches/hubs) that either auto-detects the need to cross-over, or has a switch to do it, or [c] ports on your switch that auto-detect a crossed-over connection.
Connect a DHCP client (such as a laptop) to one of the remaining three ethernet ports on the BT device. It should get an IP address from _your_ DHCP server (such as your internet router) and be able to access the internet.
Should work the same way. Configure up the WIFI to connect to your new wireless gateway: it should get an IP address from your DHCP server, and its route to the internet (its gateway) be provided at the same time.
Further notes at the link below; screenshots don’t match my device.
Footnote: on the managment (sic) page, under ‘Advanced’ / ‘Configure services’ there’s an option to disable routing. I used this for a friend’s setup, and it works a treat. However, it still tries to be an ADSL device, and will keep generating unhelpful errors until you select the right ADSL option (ie .. NOT PPPoE, etc.) that supports an ADSL device that doesn’t route. I can’t access my BT device from here, so can’t be more specific. Try then all until it works!
Using a 2700HGV as a wireless bridge/WAP
14.9.09 – “Using a 2700HGV as a wireless bridge/WAP” is now a separate page
originally posted May 2007; Windows 2000 bits left out.
I tripped over this problem a couple of times, and generally the root cause was a firewall or some sort of other TCP/IP processing software. The first instance was something that claimed to be a optimiser, and in practise was considered to be a piece of spyware. I think the anti-virus software tore it out, without realising it was taking a chunk of the OS with it.
Symptoms
msinfo32
Run msinfo32 – Microsoft thinks its in the %PATH%, but I found it in C:\Program Files\Common Files\Microsoft Shared\MSInfo
Expand components, network, and click protocol.
Its fairly verbose, but concentrate on the Name entries. On my simple XP Pro install, I have just
Microsoft also suggests the following are normal, but as I was missing them, their dire warnings that my system is broken is best ignored. There are seven potential keys if you have Novell IPX – MSAFD nwlnkipx [IPX] etc., but they start with MSAFD as well.
On the install with the ripped-out spyware, I had third party entries here.
Reset TCP/IP on Windows XP
I didn't find this particularly useful, but where as Microsoft usually hides everything in a GUI, this is really useful command line tool.
netsh provides an interface for configuring and interrogating Windows XP networking.
One of the commands is a reset command which - apparently - rewrites registry keys used by TCP/IP as if you'd uninstalled and reinstalled it. Not that it worked.
netsh int ip reset c:\resetlog.txt
Reinstall TCP/IP - Windows XP
Microsoft provides two methods. If you want to try something uninstrusive, but ineffective, I provide the first one for completeness.
1. Install TCP/IP over itself.
2. Delete the TCP/IP registry keys and reinstall
The may prevent anti-virus, internet security, or firewall packages working afterwards, so find out the license keys, if applicable first.
Microsoft claims in "How to determine and recover from Winsock2 corruption" that only the 'netsh' procedure above works under Service Pack 2. Try it first .. but I'm sure I've found this is the only effective way.
Sources
Microsoft Knowledgebase – “An operation was attempted on something that is not a socket.”
Microsoft Knowledgebase – “How to determine and recover from Winsock2 corruption”
Microsoft Knowledgebase – “How to reset Internet Protocol (TCP/IP) in Windows XP”
Interesting article off The Register which shows that the Internet isn’t as simple as it looks.
http://www.theregister.co.uk/2003/02/07/parliament_ceases_to_exist/
Registered before 1/8/96, parliament.uk didn’t technically exist, and the government couldn’t prove they owned it.
The use of uk instead of gb is an anomoly, the Defence Research Agency had a .gb site, the organisation ceased existing in 2001. http://en.wikipedia.org/wiki/.gb