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在 dhclient 调用之前测试 WiFi 是否存在/凭据？

tag-icon • tag-icon networking scripting wifi wpa-supplicant wpa-cli
在 dhclient 调用之前测试 WiFi 是否存在/凭据？

我有以下脚本，可以从当前 WiFi 网络断开连接并根据以下内容重新连接wpa_supplicant.conf：

#!/bin/bash

if iwgetid; then
    sudo wpa_cli terminate
    sudo ip addr flush wlan0
    sudo ip link set dev wlan0 down
    sudo rm -r /var/run/wpa_supplicant > /dev/null
fi

sudo wpa_supplicant -B -i wlan0 -c /etc/wpa_supplicant/wpa_supplicant.conf > /dev/null 2>&1
sudo service ntp restart
sudo ip link set dev wlan0 down
sudo ip link set dev wlan0 up
sudo dhclient wlan0

问题是，如果凭据wpa_supplicant不正确（这些凭据基于我的应用程序中的用户输入，因此很有可能），dhclient则会挂起相当长一段时间，尝试连接到 DHCP 服务器并分配 IP 地址，然后最终失败。

有没有办法在调用之前测试凭据是否正确dhclient？

答案1

这是一个示例./script，包括wpa_passphrase设置 TheSSID和 the 的命令password：

#!/bin/bash

if iwgetid; then
    wpa_cli terminate
    ip addr flush wlan0
    ip link set dev wlan0 down
    rm -r /var/run/wpa_supplicant > /dev/null
    ip link set dev wlan0 up
fi

wpa_supplicant -B -i wlan0 -c<(wpa_passphrase "$1" "$2") > /dev/null 2>&1
dhclient wlan0
service ntp restart
exit

用法：

sudo ./script "My SSID" "My-Password"

更新

如果wpa_supplicant使用给定的身份验证成功ssid，pass您将获得WPA: Key negotiation completed日志文件。

-f添加到wpa_supplicant命令中以提供文件的选项log。

grep您可以在执行命令之前检查退出状态dhclient。

#!/bin/bash

if iwgetid; then
    wpa_cli terminate
    ip addr flush wlan0
    ip link set dev wlan0 down
    rm -r /var/run/wpa_supplicant > /dev/null
    ip link set dev wlan0 up
fi
# A minimal wpa_supplicant.conf configuration file.

echo -e "\nctrl_interface=/run/wpa_supplicant \nupdate_config=1\n" > /etc/wpa_supplicant/wpa_supplicant.conf

# A prompt for SSID and WPA passphrase. The -f option to get a log file.
# sleep command will be useful because the authentication will take a few 
# second before executing grep.

echo "" > logfile

wpa_supplicant -B -i wlan0 -c<(wpa_passphrase "$1" "$2") -f logfile

sleep 10

grep -c "WPA: Key negotiation completed" logfile

if [ $? -eq 0 ] 
   then
   echo "Key negotiation completed successfully" 
   timeout 15 dhclient wlan0
   exit 0
else
  echo "Authentication failed"
fi
exit 1

用法：

sudo ./script "My SSID" "My-Password"

答案2

我会将其分解为单独的函数，以便我在重新配置网络之前测试 wifi 连接。

#!/usr/bin/env bash
CONF="/etc/wpa_supplicant/wpa_supplicant.conf"

function connect_wifi() {
    wpa_supplicant -B -i wlan0 -c $CONF >/dev/null 2>&1
}

function connect_tcpip() {
    service ntp restart
    ip link set dev wlan0 down
    ip link set dev wlan0 up
    dhclient wlan0
}

FUNC_CW=$(declare -f connect_wifi)
FUNC_CT=$(declare -f connect_tcpip)

if (sudo bash -c "$FUNC_CW; connect_wifi"); then
    sudo bash -c "$FUNC_CT; connect_tcpip"
else
    echo "Error Connecting to Wifi.  Please check your credentials and try again."
fi

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