树莓派设置USB无线网卡树莓派设置USB无线网卡

一、注意和准备 1.1 注意事项

使用无线网卡前请检查电源能否提供足够电压和电流；
使用最新系统：系统增加新网卡的支持，能免去编译驱动的麻烦；
【树莓派设置USB无线网卡】仅针对RaspberryPi 3B以下的设备，这些设备没有配备无线网卡；
请用有线ssh登入，设置过程中树莓派是需要重启无线网络。

1.2 硬件信息
先看我使用的无线网卡：

pi@raspberrypi:~ $ lsusb Bus 001 Device 004: ID 148f:760b Ralink Technology, Corp. MT7601U Wireless Adapter Bus 001 Device 003: ID 0424:ec00 Standard Microsystems Corp. SMSC9512/9514 Fast Ethernet Adapter Bus 001 Device 002: ID 0424:9514 Standard Microsystems Corp. SMC9514 Hub Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

上面显示的Ralink Technology, Corp. MT7601U Wireless Adapter是我的无线网卡。在Raspbian Stretch Lite 2017-09-07 Kernel 4.9系统镜像中已经自带该网卡的驱动。
如果你的无线网卡在系统中无法识别，请自行编译安装驱动。
1.3 查看已经连接的网络
使用iwconfig查看wlan0的详情：

pi@raspberrypi:~ $ iwconfig eth0no wireless extensions.lono wireless extensions.wlan0IEEE 802.11ESSID:"NETGEAR76" Mode:ManagedFrequency:2.462 GHzAccess Point: 10:DA:43:7A:A3:E8 Bit Rate=24 Mb/sTx-Power=20 dBm Retry short limit:7RTS thr:offFragment thr:off Power Management:off Link Quality=39/70Signal level=-71 dBm Rx invalid nwid:0Rx invalid crypt:0Rx invalid frag:0 Tx excessive retries:0Invalid misc:32Missed beacon:0

上面已经显示了连接到NETGEAR76，连接频段和信号质量等等信息。
二、配置无线网络 2.1 扫描可见SSID
通过sudo iwlist wlan0 scan扫描附近可见的SSID，并截取两个无线路由器的信息。后者NETGEAR76是已经连接的，现用前者MERCURY_4E1A演示。

pi@raspberrypi:~ $ sudo iwlist wlan0 scan wlan0Scan completed : Cell 08 - Address: E4:F3:F5:0F:4E:1A Channel:11 Frequency:2.462 GHz (Channel 11) Quality=47/70Signal level=-63 dBm Encryption key:on ESSID:"MERCURY_4E1A" Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s; 6 Mb/s 9 Mb/s; 12 Mb/s; 18 Mb/s Bit Rates:24 Mb/s; 36 Mb/s; 48 Mb/s; 54 Mb/s Mode:Master Extra:tsf=000004fb6621e986 Extra: Last beacon: 20ms ago IE: Unknown: 000C4D4552435552595F34453141 IE: Unknown: 010882848B960C121824 IE: Unknown: 03010B IE: Unknown: 2A0100 IE: Unknown: 32043048606C IE: Unknown: 2D1A6E1003FFFF000000000000000000000000000000000000000000 IE: Unknown: 3D160B071100000000000000000000000000000000000000 IE: IEEE 802.11i/WPA2 Version 1 Group Cipher : CCMP Pairwise Ciphers (1) : CCMP Authentication Suites (1) : PSK IE: WPA Version 1 Group Cipher : CCMP Pairwise Ciphers (1) : CCMP Authentication Suites (1) : PSK IE: Unknown: DD180050F2020101000003A4000027A4000042435E0062322F00 IE: Unknown: DD05000AEB0100 Cell 09 - Address: 10:DA:43:7A:A3:E8 Channel:11 Frequency:2.462 GHz (Channel 11) Quality=41/70Signal level=-69 dBm Encryption key:on ESSID:"NETGEAR76" Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s; 18 Mb/s 24 Mb/s; 36 Mb/s; 54 Mb/s Bit Rates:6 Mb/s; 9 Mb/s; 12 Mb/s; 48 Mb/s Mode:Master Extra:tsf=00000119cffe47dc Extra: Last beacon: 20ms ago IE: Unknown: 00094E4554474541523736 IE: Unknown: 010882840B162430486C IE: Unknown: 03010B IE: Unknown: 2A0100 IE: Unknown: 2F0100 IE: IEEE 802.11i/WPA2 Version 1 Group Cipher : CCMP Pairwise Ciphers (1) : CCMP Authentication Suites (1) : PSK IE: Unknown: 32040C121860 IE: Unknown: 0B0501001D0000 IE: Unknown: 7F080400080000000040 IE: Unknown: DD7B0050F204104A0001101044000102103B0001031047001021A685A13B70898A47777B80AB552F671021000D4E4554474541522C20496E632E102300055236323530102400055236323530104200033637391054000800060050F2040001101100055236323530100800022008103C0001031049000600372A000120 IE: Unknown: DD090010180201000C0000 IE: Unknown: DD180050F2020101880003A4000027A4000042435E0062322F00 IE: Unknown: 46057208010000

2.2 设置SSID和对应密码
使用命令wpa_passphrase SSID 密码生成SSID和对应的密码，复制内容备用：

pi@raspberrypi:~ $ wpa_passphrase MERCURY_4E1A blackcar network={ ssid="MERCURY_4E1A" #psk="blackcar" psk=7763537e8128e46f91200bab0a3d9adc08d701a0e1a555d0285fd1e10b185ab9 }

或通过重定向命令写入到文件备用:

pi@raspberrypi:~ $ wpa_passphrase MERCURY_4E1A blackcar > ~/wifi.conf

2.3 修改wpa_supplicant.conf
修改wpa_supplicant.conf需要管理员权限，请切换到root:

pi@raspberrypi:~ $ su Password:

把内容粘贴到/etc/wpa_supplicant/wpa_supplicant.conf：

root@raspberrypi:/home/pi# nano /etc/wpa_supplicant/wpa_supplicant.conf

或重定向的方式给wpa_supplicant.conf追加wifi.conf：

root@raspberrypi:/home/pi# less wifi.conf >> /etc/wpa_supplicant/wpa_supplicant.conf

2.4 配置文件
配置/etc/network/interfaces:

sudo nano /etc/network/interfaces

下面是我的配置，同时支持eth0和wlan0。当网线和Wifi同时连接时会独立获得ip，wlan0的配置表示通过DHCP获取IP地址。

# interfaces(5) file used by ifup(8) and ifdown(8)# Please note that this file is written to be used with dhcpcd # For static IP, consult /etc/dhcpcd.conf and 'man dhcpcd.conf'# Include files from /etc/network/interfaces.d: source-directory /etc/network/interfaces.dauto lo iface lo inet loopbackallow-hotplug eth0 iface eth0 inet dhcpallow-hotplug wlan0 auto wlan0 iface wlan0 inet dhcp pre-up wpa_supplicant -B w -D wext -i wlan0 -c /etc/wpa_supplicant/wpa_supplicant.conf post-down killall -q wpa_supplicant

2.5 重启网络
设置完成后保存退出，并重启树莓派的的网络：

sudo /etc/init.d/networking restart sudo ifup wlan0

三、查看连接后信息连接成功后，用iwconfig查看信息

pi@raspberrypi:~ $ iwconfig eth0no wireless extensions.lono wireless extensions.wlan0IEEE 802.11ESSID:"MERCURY_4E1A" Mode:ManagedFrequency:2.437 GHzAccess Point: E4:F3:F5:0F:4E:1A Bit Rate=24 Mb/sTx-Power=20 dBm Retry short limit:7RTS thr:offFragment thr:off Power Management:off Link Quality=46/70Signal level=-64 dBm Rx invalid nwid:0Rx invalid crypt:0Rx invalid frag:0 Tx excessive retries:0Invalid misc:5Missed beacon:0

用ifconfig查看可知获得IP地址：192.168.0.101

pi@raspberrypi:~ $ ifconfig lo: flags=73mtu 65536 inet 127.0.0.1netmask 255.0.0.0 inet6 ::1prefixlen 128scopeid 0x10 looptxqueuelen 1(Local Loopback) RX packets 8bytes 312 (312.0 B) RX errors 0dropped 0overruns 0frame 0 TX packets 8bytes 312 (312.0 B) TX errors 0dropped 0 overruns 0carrier 0collisions 0wlan0: flags=4163mtu 1500 inet 192.168.0.101netmask 255.255.255.0broadcast 192.168.0.255 inet6 fe80::236:76ff:fe06:8115prefixlen 64scopeid 0x20 ether 00:36:76:06:81:15txqueuelen 1000(Ethernet) RX packets 112bytes 12015 (11.7 KiB) RX errors 0dropped 0overruns 0frame 0 TX packets 101bytes 16500 (16.1 KiB) TX errors 0dropped 0 overruns 0carrier 0collisions 0