外置网卡RTL8811CU设置

UBUNTU使用RTL8811CU网卡（包含树莓派）

外置网卡配置AP模式流程

1. 检查网卡支持情况（是否支持AP模式）

iw list

找到以上部分，发现支持AP

2. 安装依赖

sudo apt-get update
sudo apt-get install hostapd dnsmasq 

3. 配置hostapd

创建和编辑hostapd配置文件

sudo gedit /etc/hostapd/hostapd.conf

更改配置文件如下，其中interface是ifconfig确定的模式，driver后面的驱动是固定的，不因为外置网卡下载不同驱动而改变

interface=wlx90de803014a8 #interface 参数定义了无线接口的名称
driver=nl80211  #driver 参数定义了使用的驱动程序，固定，不因为外置网卡设备名而改变
ssid=WL1             #wifi名称
channel=6           #channel 参数定义了网络所在的频道
auth_algs=1       #auth_algs 参数定义了用于身份验证的算法
hw_mode=g       #hw_mode 参数定义了硬件模式
ignore_broadcast_ssid=0   #ignore_broadcast_ssid 参数决定是否忽略广播的 SSID
wpa=3
wpa_passphrase=123456789    #密码
wpa_key_mgmt=WPA-PSK
wpa_pairwise=TKIP
rsn_pairwise=CCMP

#wpa 参数定义了是否使用 WPA 加密
#wpa_passphrase 参数定义了 WPA 的密码
#wpa_key_mgmt 参数定义了 WPA 的密钥管理方式
#wpa_pairwise 参数定义了 WPA 的对等加密方式
#rsn_pairwise 参数定义了 RSN 的对等加密方式

查看无线接口名称如下，插拔外置网卡判断具体是哪个

ifconfig

4. 配置hostapd配置文件
编辑/etc/default/hostapd文件

sudo gedit /etc/default/hostapd

找到DAEMON_CONF=""这一行，并替换为

DAEMON_CONF="/etc/hostapd/hostapd.conf"

5. 配置dnsmasq

sudo gedit /etc/dnsmasq.conf

文件末尾加入

interface=wlan0
dhcp-range=192.168.10.2,192.168.10.20,255.255.255.0,24h
port=5353

6. 配置网络接口

sudo gedit /etc/network/interfaces

添加以下配置

auto wlx90de803014a8
iface wlx90de803014a8 inet static
address 192.168.10.1
netmask 255.255.255.0

7. 重启服务

sudo systemctl restart hostapd
sudo systemctl restart dnsmasq

报错处理

在sudo systemctl restart hostapd出现以下报错：

Job for dnsmasq.service failed because the control process exited with error code.
See "systemctl status dnsmasq.service" and "journalctl -xe" for detail

可以通过sudo systemctl status hostapd这个命令来查看具体错误原因

● hostapd.service - Advanced IEEE 802.11 AP and IEEE 802.1X/WPA/WPA2/EAP Authenticator
   Loaded: loaded (/lib/systemd/system/hostapd.service; disabled; vendor preset: enabled)
   Active: failed (Result: exit-code) since Tue 2024-04-30 16:42:09 CST; 3s ago
  Process: 15958 ExecStart=/usr/sbin/hostapd -P /run/hostapd.pid -B $DAEMON_OPTS ${DAEMON_CONF} (code=exited, status=1/FAILURE)

4月 30 16:42:09 pc-NUC11TNKi7 systemd[1]: Starting Advanced IEEE 802.11 AP and IEEE 802.1X/WPA/WPA2/EAP Authenticator...
4月 30 16:42:09 pc-NUC11TNKi7 hostapd[15958]: Configuration file: /etc/hostapd/hostapd.conf
4月 30 16:42:09 pc-NUC11TNKi7 hostapd[15958]: Line 2: invalid/unknown driver 'rtl8821cu'
4月 30 16:42:09 pc-NUC11TNKi7 hostapd[15958]: 1 errors found in configuration file '/etc/hostapd/hostapd.conf'
4月 30 16:42:09 pc-NUC11TNKi7 hostapd[15958]: Failed to set up interface with /etc/hostapd/hostapd.conf
4月 30 16:42:09 pc-NUC11TNKi7 hostapd[15958]: Failed to initialize interface
4月 30 16:42:09 pc-NUC11TNKi7 systemd[1]: hostapd.service: Control process exited, code=exited status=1
4月 30 16:42:09 pc-NUC11TNKi7 systemd[1]: hostapd.service: Failed with result 'exit-code'.
4月 30 16:42:09 pc-NUC11TNKi7 systemd[1]: Failed to start Advanced IEEE 802.11 AP and IEEE 802.1X/WPA/WPA2/EAP Authenticator.
pc@pc-NUC11TNKi7:~$ 

以上报错是因为驱动使用了错误的rtl8821cu，修改驱动即可

在sudo systemctl restart dnsmasq同样出现报错

Job for dnsmasq.service failed because the control process exited with error code.
See "systemctl status dnsmasq.service" and "journalctl -xe" for details.

同样通过这个查看报错信息sudo systemctl status dnsmasq.service

● dnsmasq.service - dnsmasq - A lightweight DHCP and caching DNS server
   Loaded: loaded (/lib/systemd/system/dnsmasq.service; enabled; vendor preset: enabled)
   Active: failed (Result: exit-code) since Tue 2024-04-30 16:46:19 CST; 1min 36s ago
  Process: 16137 ExecStart=/etc/init.d/dnsmasq systemd-exec (code=exited, status=1/FAILURE)
  Process: 16136 ExecStartPre=/usr/sbin/dnsmasq --test (code=exited, status=0/SUCCESS)

4月 30 16:46:19 pc-NUC11TNKi7 systemd[1]: Starting dnsmasq - A lightweight DHCP and caching DNS server...
4月 30 16:46:19 pc-NUC11TNKi7 dnsmasq[16136]: dnsmasq: syntax check OK.
4月 30 16:46:19 pc-NUC11TNKi7 dnsmasq[16137]: dnsmasq: bad option at line 2 of /etc/dnsmasq.d/wlan0-ap.conf.save
4月 30 16:46:19 pc-NUC11TNKi7 dnsmasq[16137]: bad option at line 2 of /etc/dnsmasq.d/wlan0-ap.conf.save
4月 30 16:46:19 pc-NUC11TNKi7 systemd[1]: dnsmasq.service: Control process exited, code=exited status=1
4月 30 16:46:19 pc-NUC11TNKi7 dnsmasq[16137]: 启动失败
4月 30 16:46:19 pc-NUC11TNKi7 systemd[1]: dnsmasq.service: Failed with result 'exit-code'.
4月 30 16:46:19 pc-NUC11TNKi7 systemd[1]: Failed to start dnsmasq - A lightweight DHCP and caching DNS server.

以上报错是因为在/etc/dnsmasq.d/wlan0-ap.conf.save这个文件的第二行出现错误字符

● dnsmasq.service - dnsmasq - A lightweight DHCP and caching DNS server
   Loaded: loaded (/lib/systemd/system/dnsmasq.service; enabled; vendor preset: enabled)
   Active: failed (Result: exit-code) since Thu 2024-05-02 11:59:37 CST; 13s ago
  Process: 5591 ExecStart=/etc/init.d/dnsmasq systemd-exec (code=exited, status=2)
  Process: 5590 ExecStartPre=/usr/sbin/dnsmasq --test (code=exited, status=0/SUCCESS)

5月 02 11:59:37 pc-NUC11TNKi7 systemd[1]: Starting dnsmasq - A lightweight DHCP and caching DNS server...
5月 02 11:59:37 pc-NUC11TNKi7 dnsmasq[5590]: dnsmasq: syntax check OK.
5月 02 11:59:37 pc-NUC11TNKi7 dnsmasq[5591]: dnsmasq: failed to create listening socket for port 53: 地址已在使用
5月 02 11:59:37 pc-NUC11TNKi7 dnsmasq[5591]: failed to create listening socket for port 53: 地址已在使用
5月 02 11:59:37 pc-NUC11TNKi7 dnsmasq[5591]: 启动失败
5月 02 11:59:37 pc-NUC11TNKi7 systemd[1]: dnsmasq.service: Control process exited, code=exited status=2
5月 02 11:59:37 pc-NUC11TNKi7 systemd[1]: dnsmasq.service: Failed with result 'exit-code'.
5月 02 11:59:37 pc-NUC11TNKi7 systemd[1]: Failed to start dnsmasq - A lightweight DHCP and caching DNS server

以上报错是因为端口53被同时占用，在 /etc/dnsmasq.conf中换一个端口即可