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http://www.daveconroy.com/turn-your-raspberry-pi-into-a-wifi-hotspot-with-edimax-nano-usb-ew-7811un-rtl8188cus-chipset/
Posted by dconroy on Jul 10, 2013 in How To‘s, Raspberry Pi | 142 comments | 143,087 views
I’m writing this blog to help anyone with an Edimax Nano USB WiFi adapter (EW-7811Un) configure a Wireless Accesss Point. The main reason I wrote this post is because the Edimax was the first wireless adapter I ever recommended(turning a Raspberry Pi into a fully functional web server). I chose this adapter because it works out of the box, is cheap, and has a really low profile. But when I started the process of trying to turn my rPi into a WiFi hotspot, it seemed that every tutorial out there claimed that the Edimax card I had recommended “doesn’t support Access Point”.
Luckily for you and me, this is not the case.
Given the varied level of experience of my readers, this tutorial will start from scratch. If you already have your operating system running, skip forward as needed.
For this tutorial I am using Raspbian. I recommend it because it is an optimized version of Debian built specifically for Raspberry Pi’s. The last stable downloads can be found here.
To flash your SD Card, you will need to unzip the image and write it your SD card using Win32DiskImager. This tool can also be used to after our initial setup to create an image of our finalized implementation(very useful as a backup).
After the image is flashed, you can boot your device. At this point you can use your HDMI Cable/Mouse/Keyboard for your initial configuration, or you can use an SSH Client like Putty to connect. The default hostname, login, and password are as follows:
host:raspberrypi
Username: pi
Password: raspberry
For this tutorial, I will be using putty. On first boot, you will be prompted with a configuration tool called Raspi-Config. If the raspi-config doesnt load automatically, just enter the following command from the shell to get started.
sudo raspi-config
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The settings I recommend you update are
update
expand_rootfs
change_pass
change_timezone
memory_split
The usual distribution images are 2 GB. When you copy the image to a larger SD card you have a portion of that card unused. expand_rootfs expands the initial image to expand to fill the rest of the SD card, giving you more space. By default, 64mb is reserved for the Graphical UI. Since we plan on using this as a WiFi Hotspot, we can reduce this to 32mb with the memory_split command.
After you finish your changes to the raspi-config, you should reboot your pi using the following command:
sudo shutdown -r now
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At this point you have a fully functional linux server, but we still need to check our network card and setup our WiFi hotspot.
The first thing you need to do is make sure you have an existing wired connection to your rPi. After that, you need to install the following packages.
sudo apt-get install bridge-utils hostapd
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The whole crux of the issue is that it is the apt hosted copy of hostapd that is not compatible with the RTL8188CUS chipset. But, thanks to the Edimax team, I’ve got a replacement hostapd binary to resolve this issue. This tutorial will not work without it.
To download and replace the installed binary version of hostapd we just installed, issue the following commands:
wget http://www.daveconroy.com/wp3/wp-content/uploads/2013/07/hostapd.zip
unzip hostapd.zip
sudo mv /usr/sbin/hostapd /usr/sbin/hostapd.bak
sudo mv hostapd /usr/sbin/hostapd.edimax
sudo ln -sf /usr/sbin/hostapd.edimax /usr/sbin/hostapd
sudo chown root.root /usr/sbin/hostapd
sudo chmod 755 /usr/sbin/hostapd
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*Note, some people don’t like the idea of installing from untrusted 3rd parties, so if If would rather compile your own binary, you can download the realtek driver here . You will have to navigate to the ~/RTL8188C_8192C_USB_linux_v3.4.4_4749.20121105/wpa_supplicant_hostapd/wpa_supplicant_hostapd-0.8/hostapd and run a make, make install, then hostapd like i did above.
Now that we have the proper hostapd installed, we need to create a bridge between our ethernet connection and our Edimax Wireless card. To do this, we need to edit our network interfaces:
sudo nano /etc/network/interfaces
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To avoid any conflicts, you need to delete or comment out(#) any lines conatining wlan0 and then add the following text to bridge the connections, assuming your ethernet and wireless adapters are named eth0 and wlan0( use ifconfig -a to check)
auto br0
iface br0 inet dhcp
bridge_ports eth0 wlan0
The resulting file should look like this:
#loopback adapter
auto lo
iface lo inet loopback#wired adapter
iface eth0 inet dhcp#bridge
auto br0
iface br0 inet dhcp
bridge_ports eth0 wlan0
Now that our interfaces are setup, we need to configure hostapd. To do so, create the following file
sudo nano /etc/hostapd/hostapd.conf
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with the following contents:
interface=wlan0
driver=rtl871xdrv
bridge=br0
ssid=DaveConroyPi
channel=1
wmm_enabled=0
wpa=1
wpa_passphrase=ConroyPi
wpa_key_mgmt=WPA-PSK
wpa_pairwise=TKIP
rsn_pairwise=CCMP
auth_algs=1
macaddr_acl=0
We should be finished now, and afer a reboot
sudo reboot
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you can test your configuration using the following command
sudo hostapd -dd /etc/hostapd/hostapd.conf
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If it runs as expected, you can add it to startup by editing
sudo nano /etc/default/hostapd
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and uncommenting and updating the following line
DAEMON_CONF="/etc/hostapd/hostapd.conf"
That should do it! I’m happy to answer any questions, just comment on this post. Thanks for reading!
Turn Your Raspberry Pi Into a WiFi Hotspot with Edimax Nano USB EW-7811Un (RTL8188CUS chipset)
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原文地址：http://www.cnblogs.com/welhzh/p/4189626.html
