WIFI Toys

My home network has 3 annoying problems:
#1 - The house has an odd shape and Christine's office is a long way from the spot the cable comes into the house and where the wireless gateway is. The signal strength in her office is barely adequate.
#2 - I have a nice Raid5 server which I used to keep in the garage at the previous house, but in this one the Internet connection terminates inside the house and the machine is too noisy and ugly to have sitting in the dining room. I'd like to get it back into the garage, but there is no connection there currently.
#3 - There is no phone jack anywhere near the TV, so I am periodically running a long phoneline to the Tivo so it can make its daily call. This is one of old series-1 Tivos which has one of the first TivoNet cards in it, so if I could get network connectivity to the TV I could make it update via that instead.

The solution is of course to buy more toys! In this case a couple more WRT54G wireless gateways. At $79.99 from Amazon they are relatively cheap and Linksys has released all the source to the Linux-based firmware. You can get it from their GPL Code Center. People have taken this code and created their own customized firmware. The best right now is from SveaSoft.
Here is a picture of what I'd like to build:

The main AP (192.168.1.1) is the one that is there now. The secondary (192.168.1.2) is the one in the garage that I will plug my RAID5 box into solving problem #2. Christine's office is also above the garage, so this secondary AP will be the one she will associate with and hopefully get a stronger signal. That means it will have to talk to the main AP via WDS (Wireless Distribution System) and then turn around and talk to any wireless clients. The radio will have to flip back and forth and I unfortunately lose half the bandwidth that way. This is 802.11g though and currently trying to go directly from that office to the main AP on the weak signal is causing the connection to drop back to 1Mbps as it is. I am hoping to see close to 10Mbps in this new setup from this AP in repeater mode.

To solve problem #3 I am going to have a third wrt54g near the TV. This one doesn't need to repeat since it isn't that far from the main AP. All I need from it is to connect as a regular wireless client to the main AP and then act as a switch where I can plug the Tivo and probably the WMA into. The WMA has wireless, but it is only 802.11b and this way I can get more bandwidth to it by connection it to this 802.11g connected switch.

At this point I have AP #2 installed in the garage and it is working well. I ran some 30-second iperf tests on it:

AP2 = WRT54G v2.0 Satori-pre1 (AP mode w/ 40-bit WEP)
AP1 = WRT54G v1.0 Satori-pre1 (AP mode w/ 40-bit WEP)
LAN = Various Linux servers and an XP box all with 100M NICs
WAN = Thinkpad T20, Linux 2.6.3-rc2, Netgear WG511 802.11g card with the prism54 driver.

LAN-AP2-WDS-AP1-LAN   9.2 Mbits/sec
LAN-AP1-LAN          93.8 Mbits/sec
LAN-AP2-LAN          93.9 Mbits/sec
WAN-AP2-LAN          19.5 Mbits/sec
WAN-AP1-LAN          19.9 Mbits/sec
WAN-AP2-WDS-AP1-LAN   5.1 Mbits/sec
WAN-AP1-WDS-AP2-LAN   5.8 Mbits/sec

A note on the above performance numbers. There are quite a few walls between AP1 and AP2 for these measurements, so the WDS speeds are not what they could be. I tested them next to each other as well and was able to get it up to about 14 Mbits/sec. By locking it down to g-only, turning off WEP and fixing the speed to 36Mb/s I was able to get it up to 17 Mbits/sec. It's still not as fast as I would like and I think I may just get a better antenna for the main AP and have Christine connect directly to that while running the AP in the garage in client mode. This should be quite a bit faster.

I have ordered another WRT54G to sit by the TV, although I am also tempted to get a decent antenna and have one sit around in monitor mode just to keep track of what other traffic is flowing by the house here.

This Dual Diversity Flat Patch Antenna from HyperLink looks like it would be suitable to get a stronger signal to the far end of the house. Remember that the Linksys boxes come with this weird RP-TNC connector, so any antenna you buy for it should have a Female Reverse Polarity TNC on it.

[Update March 5, 2004] I picked up a couple of those Hyperlink antennas and they didn't boost things as much as I had expected. I did hook up the WRT behind the TV as per the network diagram above and am running it in client mode and it works well. It does seem like there is an issue with plugging multiple clients into it in client mode, so probably a driver bug somewhere. Nothing really to getting client mode working. Simply set it to client mode on the wireless tab of the firmware. However, I find that for some reason mine isn't associating automatically. Logging in and manually doing:

wl join Canada key 3132333435

seems to do the trick. (Not my real key obviously) You can then check the status with:

# wl assoc
SSID: "Canada"
Mode: Managed   RSSI: -40 dBm   noise: -85 dBm  Channel: 3
BSSID: 00:06:25:C5:32:21        Capability: ESS WEP ShortSlot
Supported Rates: [ 1(b) 2(b) 5.5(b) 6 9 11(b) 12 18 24 36 48 54 ]

One very useful feature of client mode would be to bring it on trips. With its superior radio combined with one of the Hyperlink antennas it should be able to pick up open gateways at quite a distance. See the Kismet post for further details on using it for finding gateways and with client mode you could then associate the wrt with a gateway and plug yourself into one of the wired ports. No more messing around with wireless drivers on your laptop.

WDS mode between AP1 and AP2 is all done through the web interface as well. Each WDS endpoint needs an ip. 10.0.0.1 and 10.0.0.2 in my case. Then specify the MAC of the other AP in each web interface. Make sure both are set to the same channel and same ESSID and turn off any firewalling. There is one step the current firmware doesn't handle, so you need to do that manually after each reboot. Either via the Administration->Diagnostics tab in the web interface or by logging in, issue this:

brctl addif br0 wds0.2

to add the wds link to the LAN bridge. After doing these steps you should be able to ping the other side.

[update] As Sean Lincolne pointed out, squishguava, the boot image this thing loads over the network when it boots, is just a simple cramfs image. The "COMPRESSED ROMFS" in my earlier 'strings' is a dead give-away on this. I finally got some time to have a peek at it. It has the following in it:

libc-2.1.3.so*	libm-2.1.3.so*	librms.so*	rio*
libdl-2.1.3.so*	libmp3msp.so*	libthreadutil.so*	scripts/
libhttpmsp.so*	libmrdi.so*	libwmamsp.so*	version.txt
libiupnp.so*	liboalmsp.so*	mrd*	web/
libixml.so*	libpil.so*	mrdDevice*
libllmsp.so*	libpthread-0.8.so*	pilreg.dat*

It is obviously not a full Linux filesystem, as can be seen by looking at files in the scripts directory, this filesystem gets mounted on /guava. I compiled a small statically linked busybox and stuck it in bb/ which among other things had bb/sbin/telnetd in it. Then I hacked up scripts/rio-script and had it launch the telnetd right before it launches the rio. Built a new cramfs squishguava image and booted with it. It actually booted just fine. I was worried they might have some sort of checksum check, or my added 600k would overflow something, but it was fine. The bad news is that I couldn't get in via telnet. So, either, my telnetd didn't start properly, or the port is blocked.

I did notice that the default shell is /bin/ash which also happens to be the default shell in BusyBox and Linksys has used Busybox on other devices in the past. I bet the rom firmware which has the root filesystem for this thing is just a busybox image. So a bit more hacking on that rio-script should let me either somehow get a message out to me by trying various standard busybox commands, or I can run some stuff to try to deblock the port. Any suggestions on what is likely to work right away?

More info. I replaced the rio binary with my arm cross-compiled telnetd binary and it then doesn't get beyond the "Launching remote-IO" message during boot. At least it tells me that what I am doing has some effect. But I still can't get in via telnet. I also tried replacing it with a script that tried to ping out, cat stuff to /dev/dsp and echo stuff to various devices and none of that did anything I could see/hear.
[/update]

This looks like a nifty little box that will make it easy to access mp3's and photos directly from a remote-control TV-displayed interface. Much nicer than needing to stick a PC next to the TV/Stereo in the living room.

This little device showed up today. Had no trouble configuring it and hooking it up once I shuffled the various cables around a bit on the back of the TV and stereo. The music navigator is really nice on it and I like that you can play mp3's while a photo album is cycling through. Will have to try this thing against some Samba shares later on.

No luck on the Samba shares, or any sort of shares at all actually. I did a bit of sniffing of the datastream between the WMA and XP. When it starts up the first thing it does after getting an IP via DHCP is to grab its OS image from the XP box. That image is clearly a Linux 2.4.17 kernel and all communications appear to be via a UPnP A/V Media Renderer SOAP thing. As far as I can tell, when you designate a directory via the Media tool on the XP box, it creates a regular .m3u playlist out of that and serves it up to the WMA when requested. There doesn't appear to be any encryption involved, so getting this thing to work with a Linux box as the server would involve creating a UPnP SOAP server that understood the requests from the WMA. Not that this is a trivial effort, but certainly not impossible and once done this thing would be able to serve files up from anywhere a Linux box could access files from. Frankly I don't see why the heck the SOAP server they provide for XP can't serve up its playlists from a network share. There doesn't appear to be any technical reason for this restriction. I bet that with a bit of hacking and with the help of libupnp this is quite feasible.

Or, alternatively, create a custom image from the sources Linksys is supposed to provide. They have their GPL Page but it doesn't list the WMA11B (yet?). As George notes, SOAP isn't exactly ideal for something as simple as moving mp3s and image files around. An alternate image that was able to mount shares directly, would be cool. It might require sticking a .m3u playlist file in each directory so you wouldn't need to do that on the WMA, but that wouldn't bug me either.

For more info on the technology in this device, have a read through Intel's Digital Home Site or see the extended entry for some nitty-gritty protocol details.

I've given up on the idea of a PCI 802.11g card for the Linux server. Driver issues are too annoying and an 802.11g bridge isn't much more expensive anyway. So now the problem becomes finding a good bridge. The Netgear WGE 101 seems like it might do the trick. At around $95 it is also one of the cheaper ones.
The WET54G is the Linksys bridge. Reviews are not very flattering and it is more expensive.
The WGA54G is the Linksys game adapter which doesn't have anything to do with games, of course. It just means it is a single-port bridge and it is a bit cheaper than the WET54G. But unless it was much cheaper than the Netgear I think I'd still prefer the Netgear.
Another option would be to pick up another WRT54G since it can be hacked into acting as a bridge if you turn on WDS support.
And finally there is the D-Link DWL-G810. I have not had good luck with D-Link gear in the past and it also looks rather ugly. Anybody out there have one of these?