Post updated 4 Jan 2014 with expanded technical details.I got a Raspberry Pi for Christmas. After connecting it up and checking that it worked I wanted to find something productive for it to do. Saving power and removing clutter are always good goals, so I decided to replace the old Windows XP laptop sitting under the TV currently being used, occasionally, as a wireless bridge for our PVR. Using the standard Raspbian Linux distribution this was relatively easy to set up, though there's a bit to learn if you haven't fiddled with networking in Linux for a while.
Our PVR has an ethernet port but no wireless capabilities, so a wireless bridge is needed to connect it to the internet. Tiny $25 routers, such as the TP-Link TL-WR702N, can easily be configured as wireless bridges, so if I didn't already have a Pi or a spare laptop I'd go for one of them. That router, like the Pi, can be powered via USB, which means the power can come from a recent TV or PVR with a spare USB port, rather than a less efficient bulky power brick.
Note: These instructions were written for and tested on 2013-02-09-wheezy-raspbian. Other versions may not work identically.
After you first boot Raspbian you'll need to tell it how to connect to your wireless network. If you are in xwindows then you should see a WiFi Config icon. Using that should be straightforward, although if you're connected to a display via composite rather than HDMI then you may find the resolution of the screen too low to see the necessary elements of the various WiFi Config windows. If you hold down alt then you can click anywhere within the window to drag it around, thereby showing the crucial bits.
The most important command to learn is
ifconfig. This will tell you the current status of your network, so use it liberally. Some sample output from this command is below.The WiFi config icon calls wpa_gui, the graphical front-end for wpa_supplicant. wpa_supplicant is the backend code coordinating the wireless. Being Linux, there is also a console interface, called wpa_cli. Within
wpa_cli I ran the following commands to configure the box to see my wireless network, telling it the SSID and wireless password.status
add_network
set_network 0 ssid "my-wifi-network-ssid-name"
set_network 0 psk "my-wifi-password"
enable_network 0
scan
scan_results
bssid / frequency / signal level / flags / ssid
11:11:11:11:11:11 2462 70 [WPA-PSK-CCMP][WPA2-PSK-CCMP][ESS] my-wifi-network-ssid-name
12:11:11:11:11:11 2462 26 [WPA-PSK-TKIP][ESS] ANOTHER-NETWORK
reassociate
save_config
At this point running status should return something like:
> status
bssid=11:11:11:11:11:11
ssid=my-wifi-network-ssid-name
id=0
mode=station
pairwise_cipher=CCMP
group_cipher=CCMP
key_mgmt=WPA2-PSK
wpa_state=COMPLETED
address=11:11:11:11:11:11
The changes you have made will be visible in your config file:
pi@raspberrypi ~ $ sudo cat /etc/wpa_supplicant/wpa_supplicant.conf
ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
network={
ssid="my-wifi-network-ssid-name"
psk="my-wifi-password"
}
You should now have full internet connectivity, so pinging a machine should return something like:
> pi@raspberrypi /etc/network $ ping google.com
PING google.com (74.125.237.169) 56(84) bytes of data.
64 bytes from syd01s18-in-f9.1e100.net (74.125.237.169): icmp_req=1 ttl=57 time=81.7 ms
I found the following sites useful in working out how to set this up:
These led me to the following. Firstly, install the bridging software:
apt-get install bridge-utilsBring down your networking with
sudo ifdown -aThen edit your /etc/network/interfaces file to become:
auto lo
iface lo inet loopback
iface eth0 inet manual
auto wlan0
iface wlan0 inet manual
auto br0
iface br0 inet dhcp
bridge_ports wlan0 eth0
bridge_stp off
bridge_fd 0
bridge_waitport 0
wpa-iface wlan0
wpa-bridge br0
wpa-driver wext
wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf
sudo ifup -a
I was having trouble with the Pi sometimes taking a while to receive an IP address, which I suspect is related to our temperamental router, so I've since changed to static ip rather than dhcp, as follows, remembering to manually bring down the network before making the changes, then up again afterwards:
pi@raspberrypi ~ $ cat /etc/network/interfaces
auto lo
iface lo inet loopback
iface eth0 inet manual
auto wlan0
iface wlan0 inet manual
auto br0
iface br0 inet static
address 10.1.1.13
gateway 10.1.1.1
netmask 255.255.255.0
bridge-ports wlan0 eth0
bridge-stp off
bridge-fd 0
bridge-waitport 0
wpa-iface wlan0
wpa-bridge br0
wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf
ifstatus should get the following:
pi@raspberrypi ~ $ ifstatus
*** Usage of ifstatus is deprecated, use ifplugstatus instead! ***
br0: link beat detected
wlan0: link beat detected
lo: link beat detected
eth0: link beat detectedifconfig should now show something like:
pi@raspberrypi /etc/network $ ifconfig
br0 Link encap:Ethernet HWaddr 11:11:11:11:11:11
inet addr:10.1.1.13 Bcast:10.1.1.255 Mask:255.255.255.0
inet6 addr: 2222::2222:2222:2222:2222/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:151 errors:0 dropped:1 overruns:0 frame:0
TX packets:132 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:12263 (11.9 KiB) TX bytes:15361 (15.0 KiB)
eth0 Link encap:Ethernet HWaddr 11:11:11:11:11:11
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:3 errors:0 dropped:0 overruns:0 frame:0
TX packets:24 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:166 (166.0 B) TX bytes:1563 (1.5 KiB)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
wlan0 Link encap:Ethernet HWaddr 11:11:11:11:11:11
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:329 errors:0 dropped:346 overruns:0 frame:0
TX packets:136 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:84768 (82.7 KiB) TX bytes:19563 (19.1 KiB)