2019独角兽企业重金招聘Python工程师标准>>> 
centos 安装网桥管理工具以及ifconfig：
[root@localhost ~]# yum install bridge-utils
[root@localhost ~]# yum search ifconfig
已加载插件：fastestmirror
Loading mirror speeds from cached hostfile
* base: mirrors.nwsuaf.edu.cn
* extras: mirrors.tuna.tsinghua.edu.cn
* updates: mirrors.tuna.tsinghua.edu.cn
================================== 匹配：ifconfig ==================================
net-tools.x86_64 : Basic networking tools
[root@localhost ~]# yum install net-tools.x86_64
已加载插件：fastestmirror
Loading mirror speeds from cached hostfile
* base: mirrors.nwsuaf.edu.cn
* extras: mirrors.tuna.tsinghua.edu.cn
* updates: mirrors.tuna.tsinghua.edu.cn
正在解决依赖关系
--> 正在检查事务
---> 软件包 net-tools.x86_64.0.2.0-0.24.20131004git.el7 将被 安装
--> 解决依赖关系完成
依赖关系解决
====================================================================================
Package 架构 版本 源 大小
====================================================================================
正在安装:
net-tools x86_64 2.0-0.24.20131004git.el7 base 306 k
事务概要
====================================================================================
安装 1 软件包
总下载量：306 k
安装大小：918 k
Is this ok [y/d/N]: y
Downloading packages:
net-tools-2.0-0.24.20131004git.el7.x86_64.rpm | 306 kB 00:00:00
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
正在安装 : net-tools-2.0-0.24.20131004git.el7.x86_64 1/1
验证中 : net-tools-2.0-0.24.20131004git.el7.x86_64 1/1
已安装:
net-tools.x86_64 0:2.0-0.24.20131004git.el7
完毕！
然后可以查看网桥连接情况
（在此之前已经启动了一个docker容器：
root@9d04fa294f9f:/# ifconfig
eth0: flags=4163
inet 172.17.0.2 netmask 255.255.0.0 broadcast 172.17.255.255
ether 02:42:ac:11:00:02 txqueuelen 0 (Ethernet)
RX packets 4764 bytes 16630698 (16.6 MB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 3394 bytes 187733 (187.7 KB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
lo: flags=73
inet 127.0.0.1 netmask 255.0.0.0
loop txqueuelen 1000 (Local Loopback)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
）
[root@localhost ~]# brctl show
bridge name bridge id STP enabled interfaces
docker0 8000.02421eb87b8e no veth7e77e4c
veth7e77e4c: flags=4163
inet6 fe80::588d:28ff:febe:c60e prefixlen 64 scopeid 0x20
ether 5a:8d:28:be:c6:0e txqueuelen 0 (Ethernet)
RX packets 3394 bytes 187733 (183.3 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 4764 bytes 16630698 (15.8 MiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
docker0: flags=4163
inet 172.17.0.1 netmask 255.255.0.0 broadcast 172.17.255.255
inet6 fe80::42:1eff:feb8:7b8e prefixlen 64 scopeid 0x20
ether 02:42:1e:b8:7b:8e txqueuelen 0 (Ethernet)
RX packets 3394 bytes 140217 (136.9 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 4764 bytes 16630698 (15.8 MiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
通过ifconfig查看宿主机的docker0的网络设备，docker守护进程就是通过docker0为docker的容器提供网络连接的各种服务。
docker0是Linux虚拟网桥。
Linux虚拟网桥的特点:
- 可以设置IP地址
- 相当于拥有一个隐藏的虚拟网卡
docker守护进程在一个容器启动时，实际上它要创建网络连接的两端。一端是在容器中的网络设备，而另一端是在运行docker守护进程的主机上打开一个名为veth*的一个接口，用来实现docker这个网桥与容器的网络通信。