1.前言
之前买了一个工控机,装过几个OS(linux 发行版),但是一直没有细研究过流程,只是停留在能用就不管了,工控机自带无线网卡(和俩个有线网口),所以这篇文章好好介绍如何开机自动连接WIFI(无图形化界面)。
2.安装软件
首先系统我安装的是 ubuntu 18.04 server版 ,安装过程不必赘述。
要连接家里的wifi,首先要知道家里wifi的加密模式,是否为WEP模式。
无密码/WEP模式可直接使用以下命令连接:
sudo iw dev wlan0 connect [网络 SSID]
sudo iw dev wlan0 connect [网络 SSID] key 0:[WEP 密钥]
如果是WPA 或WPA2 需要安装 wpasupplicant 软件包
sudo apt install wpasupplicant
3.生成配置文件
sudo wpa_passphrase [网络SSID] [KEY秘钥] > /etc/wpa_supplicant.conf
4.连接WIFI
wpa_supplicant -s -i wlp3s0 -D nl80211,wext -c /etc/wpa_supplicant.conf
看到很多文章说 加 &
放到后台执行,其实 wpa_supplicant -B
参数就是放到后台去执行。
动态获取ip地址:
dhclinet
验证是否可以连接网络:
curl www.baidu.com
4.开机自动连接WIFI
修改 /etc/network/interfaces
文件:
# ifupdown has been replaced by netplan(5) on this system. See
# /etc/netplan for current configuration.
# To re-enable ifupdown on this system, you can run:
# sudo apt install ifupdown
auto wlp3s0
iface wlp3s0 inet dhcp
wpa-conf /etc/wpa_supplicant.conf
可以看到这个配置文件前面说明了ifupdown 工具已经被 netplan 替换掉了,如果使用 ifupdown 这个工具就需要安装一下:
sudo apt install ifupdown
ifup,ifdown 命令会读取 /etc/network/interfaces
进行设置:
ifup wlp3s0 #启用wlp3s0 并连接wifi
ifdown wlp3s0 #关闭wlp3s0
ifup,ifdown 命令也是通过服务来控制的:(/etc/systemd/system/network-online.target.wants/networking.service
)
[Unit]
Description=Raise network interfaces
Documentation=man:interfaces(5)
DefaultDependencies=no
Wants=network.target
After=local-fs.target network-pre.target apparmor.service systemd-sysctl.service systemd-modules-load.service
Before=network.target shutdown.target network-online.target
Conflicts=shutdown.target
[Install]
WantedBy=multi-user.target
WantedBy=network-online.target
[Service]
Type=oneshot
EnvironmentFile=-/etc/default/networking
ExecStartPre=-/bin/sh -c '[ "$CONFIGURE_INTERFACES" != "no" ] && [ -n "$(ifquery --read-environment --list --exclude=lo)" ] && udevadm settle'
ExecStart=/sbin/ifup -a --read-environment
ExecStop=/sbin/ifdown -a --read-environment --exclude=lo
RemainAfterExit=true
TimeoutStartSec=5min
networking 这个服务是开机自启服务,每次开机就会执行/sbin/ifup -a --read-environment
,从而连接wifi。
5. 其它问题
A start job is running for wait for network to be Configured
开机卡住2分钟左右。
很多文章也说过,修改/etc/systemd/system/network-online.target.wants/systemd-networkd-wait-online.service
:
# SPDX-License-Identifier: LGPL-2.1+
#
# This file is part of systemd.
#
# systemd is free software; you can redistribute it and/or modify it
# under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation; either version 2.1 of the License, or
# (at your option) any later version.
[Unit]
Description=Wait for Network to be Configured
Documentation=man:systemd-networkd-wait-online.service(8)
DefaultDependencies=no
Conflicts=shutdown.target
Requires=systemd-networkd.service
After=systemd-networkd.service
Before=network-online.target shutdown.target
[Service]
Type=oneshot
ExecStart=/lib/systemd/systemd-networkd-wait-online
RemainAfterExit=yes
TimeoutStartSec=2sec #其它文章加入的
[Install]
WantedBy=network-online.target
简单来说 systemd-networkd-wait-online 这个服务可以检查所有网络接口网络是否处于就绪状态,如果没就绪就会阻塞住,但是直接设置服务的 timeout时间并不是好的做法。
我们简单执行一下 /lib/systemd/systemd-networkd-wait-online
这个命令:
root@ubuntu:~# /lib/systemd/systemd-networkd-wait-online --help
systemd-networkd-wait-online [OPTIONS...]
Block until network is configured.
-h --help Show this help
--version Print version string
-q --quiet Do not show status information
-i --interface=INTERFACE Block until at least these interfaces have appeared
--ignore=INTERFACE Don't take these interfaces into account
--timeout=SECS Maximum time to wait for network connectivity
root@ubuntu:~#
可以看到,这个命令是可以带有一些参数的,-i 判断指定的网络接口,不必判断所有的网络接口,所以这地方我只有指定我连接wifi的网络接口就合理了:
ExecStart=/lib/systemd/systemd-networkd-wait-online -i wlp3s0
标签:systemd,network,--,networkd,WIFI,server,online,Linux,target
From: https://blog.51cto.com/u_13589616/5890241