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参考：
http://www.infoq.com/cn/articles/docker-network-and-pipework-open-source-explanation-practice
http://www.oschina.net/translate/docker-network-configuration
--net=host
docker使用linux的namespace进行资源隔离，支持CPU namespace，network namesapce等。一个Network Namespace提供了一份独立的网络环境，包括网卡、路由、Iptable规则等都与其他的Network Namespace隔离。
如果docker容器使用host模式，docker容器没有分配独立的network namespace，没有独立的IP，和主机共享IP，端口，网卡，路由等
宿主机，IP为172.31.12.125
执行ifconfig：
docker0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 172.17.0.1 netmask 255.255.0.0 broadcast 0.0.0.0
inet6 fe80::42:63ff:fe23:ee0d prefixlen 64 scopeid 0x20<link>
ether 02:42:63:23:ee:0d txqueuelen 0 (Ethernet)
RX packets 1403670 bytes 864221548 (824.1 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 1408014 bytes 1359202385 (1.2 GiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 9001
inet 172.31.12.125 netmask 255.255.240.0 broadcast 172.31.15.255
inet6 fe80::c0:6ff:fe61:3127 prefixlen 64 scopeid 0x20<link>
ether 02:c0:06:61:31:27 txqueuelen 1000 (Ethernet)
RX packets 4151187 bytes 1602103237 (1.4 GiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 4382161 bytes 1414120207 (1.3 GiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 0 (Local Loopback)
RX packets 11231261 bytes 7850587697 (7.3 GiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 11231261 bytes 7850587697 (7.3 GiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
启动docker
docker run --net="host" -ti test/redis:2.6 /bin/bash
进入容器后，ifconfig查看IP
eth0 Link encap:Ethernet HWaddr 02:C0:06:61:31:27
inet addr:172.31.12.125 Bcast:172.31.15.255 Mask:255.255.240.0
inet6 addr: fe80::c0:6ff:fe61:3127/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:9001 Metric:1
RX packets:4151539 errors:0 dropped:0 overruns:0 frame:0
TX packets:4382518 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:1602135600 (1.4 GiB) TX bytes:1414191537 (1.3 GiB)
发现docker容器的IP和宿主机一样
在宿主机中启动redis并设置值
[root@ip-172-31-12-125 ~]# redis-cli redis 127.0.0.1:6379> keys * (empty list or set) redis 127.0.0.1:6379> set a haha OK redis 127.0.0.1:6379> get a "haha" redis 127.0.0.1:6379>
在宿主机中查看
[root@ip-172-31-12-125 ~]# netstat -nltp | grep 6379 tcp 0 0 0.0.0.0:6379 0.0.0.0:* LISTEN 23619/redis-server [root@ip-172-31-12-125 ~]# /usr/local/bin/redis-cli redis 127.0.0.1:6379> get a "haha"
发现宿主机中，可以探测到docker容器中启动的redis端口，并且能获取对应的值
todo
--net=brige， 默认的网络配置，如果不显示制定--net配置，docker容器默认使用brige模式
brige模式会为每一个容器分配Network Namespace,以及设置IP等，并将一个主机上的Docker容器连接到一个虚拟网桥上。
docker在启动的时候，默认会在宿主机上创建docker0的虚拟网桥，一般docker会选择172.17.0.0/16网段作为容器IP地址段，并将172.17.42.1/16分配给docker0网桥
流程：
- 在宿主机创建veth虚拟网卡，以veth*格式，veth pair以成对方式出现
- docker将veth pair的一段放到创建的容器中，并命名为eth0，另一端在宿主机以veth*名字命名，并加入到docker0网桥中，通过brctl show可以查看
- 将docker0网段中分一个IP给容器使用，并设置docker0的IP地址为默认网关宿主机
宿主机执行ifconfig：
docker0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 172.17.0.1 netmask 255.255.0.0 broadcast 0.0.0.0
inet6 fe80::42:63ff:fe23:ee0d prefixlen 64 scopeid 0x20<link>
ether 02:42:63:23:ee:0d txqueuelen 0 (Ethernet)
RX packets 1403670 bytes 864221548 (824.1 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 1408014 bytes 1359202385 (1.2 GiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 9001
inet 172.31.12.125 netmask 255.255.240.0 broadcast 172.31.15.255
inet6 fe80::c0:6ff:fe61:3127 prefixlen 64 scopeid 0x20<link>
ether 02:c0:06:61:31:27 txqueuelen 1000 (Ethernet)
RX packets 4151187 bytes 1602103237 (1.4 GiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 4382161 bytes 1414120207 (1.3 GiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 0 (Local Loopback)
RX packets 11231261 bytes 7850587697 (7.3 GiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 11231261 bytes 7850587697 (7.3 GiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
如图，发现宿主机上已经有docker0虚拟网桥，IP为172.17.0.1（宿主机为AWS的EC2机器，正常物理机的话，IP为172.17.42.1）
用brige方式启动docker
docker run --net="bridge" -ti test/redis:2.6 /bin/bash
在容器内查看
容器内执行ifconfig
eth0 Link encap:Ethernet HWaddr 02:42:AC:11:00:03
inet addr:172.17.0.3 Bcast:0.0.0.0 Mask:255.255.0.0
inet6 addr: fe80::42:acff:fe11:3/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:8 errors:0 dropped:0 overruns:0 frame:0
TX packets:8 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:648 (648.0 b) TX bytes:648 (648.0 b)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
发现容器内分配了一个IP 172.17.0.3
查看宿主机ifconfig
宿主机执行ifconfig
docker0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 172.17.0.1 netmask 255.255.0.0 broadcast 0.0.0.0
inet6 fe80::42:63ff:fe23:ee0d prefixlen 64 scopeid 0x20<link>
ether 02:42:63:23:ee:0d txqueuelen 0 (Ethernet)
RX packets 1403678 bytes 864222084 (824.1 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 1408014 bytes 1359202385 (1.2 GiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 9001
inet 172.31.12.125 netmask 255.255.240.0 broadcast 172.31.15.255
inet6 fe80::c0:6ff:fe61:3127 prefixlen 64 scopeid 0x20<link>
ether 02:c0:06:61:31:27 txqueuelen 1000 (Ethernet)
RX packets 4636333 bytes 1663112300 (1.5 GiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 4953477 bytes 1534107877 (1.4 GiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 0 (Local Loopback)
RX packets 11256543 bytes 7851902509 (7.3 GiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 11256543 bytes 7851902509 (7.3 GiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
veth32796b4: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet6 fe80::c85b:82ff:fef3:9163 prefixlen 64 scopeid 0x20<link>
ether ca:5b:82:f3:91:63 txqueuelen 0 (Ethernet)
RX packets 8 bytes 648 (648.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 8 bytes 648 (648.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
发选新增了一个veth32796b4的虚拟网卡
执行brctl show:
[root@ip-172-31-12-125 ~]# brctl show
bridge name bridge id STP enabled interfaces
docker0 8000.02426323ee0d no veth32796b4
发现veth32796b4网卡绑定在docker0网桥上
在容器内启动redis
[root@06680c786ada ~]# ./control -m 512mb start & [1] 18 [root@06680c786ada ~]# ps ux USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND root 1 0.0 0.0 11492 1776 ? Ss 03:57 0:00 /bin/bash root 18 0.0 0.0 11352 1440 ? S 04:09 0:00 /bin/sh ./control -m 512mb start root 24 0.0 0.0 36416 7528 ? Sl 04:09 0:00 /usr/local/bin/redis-server /etc/redis/redis.c root 27 0.0 0.0 13368 1044 ? R+ 04:10 0:00 ps ux [root@06680c786ada ~]# netstat -nltp | grep 6379 tcp 0 0 0.0.0.0:6379 0.0.0.0:* LISTEN 24/redis-server
如图在容器内启动redis-server，并绑定在6379端口
宿主机查看端口
[root@ip-172-31-12-125 ~]# ps aux | grep redis-server | grep -v grep [root@ip-172-31-12-125 ~]# netstat -nltp | grep 6379
如图，由于为docker容器分配了独立的network namespace，因此在宿主机上看不到redis的进程，而且也查看不到绑定的端口
通过-p启动docker容器和redis
# 启动docker容器 [root@ip-172-31-12-125 ~]# docker run --net="bridge" -ti -p 16379:6379 nd/redis:2.6 /bin/bash # 启动redis [root@aaf1c7f79a1b /]# /root/control -m 512mb start & [1] 13 # 查看redis进程 [root@aaf1c7f79a1b /]# ps aux | grep redis root 19 0.0 0.0 36416 7524 ? Sl 04:18 0:00 /usr/local/bin/redis-server /etc/redis/redis.conf root 23 0.0 0.0 6492 664 ? S+ 04:19 0:00 grep redis # 查看端口占用 [root@aaf1c7f79a1b /]# netstat -nltp | grep 6379 tcp 0 0 0.0.0.0:6379 0.0.0.0:* LISTEN 19/redis-server [root@aaf1c7f79a1b /]# netstat -nltp | grep 16379
如图，在通过-p把容器的6379绑定到宿主机的16379端口，在容器内redis服务顺利启动，并成功绑定6379端口
查看宿主机
# 没有看到对应进程 [root@ip-172-31-12-125 ~]# ps aux | grep redis-server | grep -v grep # 查看6379端口，无绑定 [root@ip-172-31-12-125 ~]# netstat -nltp | grep 6379 tcp6 0 0 :::16379 :::* LISTEN 4238/docker-proxy # 查看16379端口，绑定 [root@ip-172-31-12-125 ~]# netstat -nltp | grep 16379 tcp6 0 0 :::16379 :::* LISTEN 4238/docker-proxy
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原文地址：http://www.cnblogs.com/SailorXiao/p/5808852.html
