wpa_supplicant is an open source software project, which realizes the function of managing and controlling wireless networks in WIFI STA mode. It is a tool for connecting and configuring WIFI, mainly including two programs: wpa_supplicant and wpa_cli.
Prepare third-party software as follows:
Download link: wpa_supplicant software package free download
One, wpa_supplicant installation
Description: wpa_supplicant depends on openssl and libnl.
1. Install openssl
1) Unzip
$ tar -xvzf openssl-1.1.1d.tar.gz
$ cd openssl-1.1.1d
2) Configuration
$ mkdir /home/dongao/tools/openssl //New directory
$ ./config no-asm shared –prefix=/home/dongao/tools/openssl CROSS_COMPILE=aarch64-linux-gnu- //Configuration
–prefix : used to specify the compilation result storage directory, set to the directory just created.
$ vi Makefile //Remove the -m64 inside (the -m64 command passed in FLAG) 
3) Execute the installation
$ make
$ make install
4) Copy the libcrypto and libssl libraries under the lib directory to the /usr/lib directory of the ARM board root file system
$ sudo cp libcrypto.so* ~/share/wifi/lib/openssl/
$ sudo cp libssl.so* ~/share/wifi/lib/openssl/
2. Install libnl
1) Install dependent environment
$ sudo apt-get install flex
$ sudo apt-get install bison
2) Unzip
$ tar -xzf libnl-3.2.23.tar.gz
$ cd libnl-3.2.23
3) Configuration
$ mkdir /home/dongao/tools/libnl //New installation directory
$ ./configure –host=aarch64-linux-gnu –prefix=/home/dongao/tools/libnl //Configuration
–host : Used to specify the prefix of the cross compiler, set to “aarch64-linux-gnu” here;
–prefix : Used to specify the compilation result storage directory, set to the libnl folder just created.
4) install
$ make //compile
$ make install //installation
5) Copy the library files in the lib directory to the /usr/lib directory of the ARM root file system
$ cd /home/dongao/tools/libnl
$ sudo cp lib/* ~/share/wifi/lib/libnl_lib/ -rf
3. Install wpa_supplicant
1) Unzip
$ tar -xzf wpa_supplicant-2.7.tar.gz
$ cd wpa_supplicant-2.7/wpa_supplicant/
2) Configuration
$ cp defconfig.config
$ vi.config
3) compile
$ export PKG_CONFIG_PATH=/home/dongao/tools/libnl/lib/pkgconfig:$PKG_CONFIG_PATH //Specify the libnl library pkgconfig package location
$ make //compile
The successfully compiled files are as follows:
Copy wpa_cli and wpa_supplicant to ARM board.
$ wpa_supplicant -v //View version
2. Use of wpa_supplicant
Preparations: The wifi driver needs to be loaded successfully
1. Create wpa_supplicant.conf configuration file
$ vi /etc/wpa_supplicant.conf //Create a configuration file named “wpa_supplicant.conf” in the etc directory
ctrl_interface=/var/run/wpa_supplicant
ap_scan=1
network={
scan_ssid=1
ssid="xd iphone"
key_mgmt=WPA-PSK
psk="8888asdf"
}
$ mkdir /var/run/wpa_supplicant -p //wpa_supplicant tool needs to use this directory
2. Connect to wifi
$ wpa_supplicant -D nl80211 -i mlan0 -c /etc/wpa_supplicant.conf -B //Connect wifi
-D: driver name (can be multiple drivers: nl80211, wext)
-i: interface name (mlan0 is the STA NIC)
-c: configuration file
-B: run the daemon in the background
3. View the status of the mlan0 network card
$ wpa_cli -i mlan0 status //Check the connection status, the following information indicates the connection is successful
4. After connecting to wifi, dynamically obtain the ip address
$ udhcpc -i mlan0 //DHCP automatically obtains ip
Encountered a problem: Why does mlan0 have no IP address after DHCP automatically obtains ip?
Reason: After the arm motherboard obtains the ip with udhcpc, it is not directly set on the mlan0 network card. Because there is no script to set this IP (no /usr/share/udhcpc/default.script script)
$ udhcpc -h
Solution: $ udhcpc -i mlan0 -s /etc/udhcpc.script , or copy /etc/udhcpc.script to /usr/share/udhcpc/default.script and execute udhcpc -i mlan0 again.
After that mlan0 has an ip address.
5. Test
$ ping -I 172.20.10.8 www.baidu.com //Specify the mlan0 network card to ping the external network
Test OK