Docker系列5：网络名称空间管理

一、ip命令介绍

ip命令是iproute软件的程序

[root@host1 ~]# yum install iproute -y [root@host1 ~]# rpm -q iprouteiproute-4.11.0-25.el7_7.2.x86_64

通过ip可以实现管理网络名称空间

[root@host1 ~]# ipUsage: ip [ OPTIONS ] OBJECT { COMMAND | help }       ip [ -force ] -batch filenamewhere  OBJECT := { link | address | addrlabel | route | rule | neigh | ntable |                   tunnel | tuntap | maddress | mroute | mrule | monitor | xfrm |                   netns | l2tp | fou | macsec | tcp_metrics | token | netconf | ila |                   vrf }       OPTIONS := { -V[ersion] | -s[tatistics] | -d[etails] | -r[esolve] |                    -h[uman-readable] | -iec |                    -f[amily] { inet | inet6 | ipx | dnet | mpls | bridge | link } |                    -4 | -6 | -I | -D | -B | -0 |                    -l[oops] { maximum-addr-flush-attempts } | -br[ief] |                    -o[neline] | -t[imestamp] | -ts[hort] | -b[atch] [filename] |                    -rc[vbuf] [size] | -n[etns] name | -a[ll] | -c[olor]}

• OBJECT中的netns可以用来设置网络名称空间
  

netns的使用帮助如下

[root@host1 ~]# ip netns helpUsage: ip netns list       ip netns add NAME       ip netns set NAME NETNSID       ip [-all] netns delete [NAME]       ip netns identify [PID]       ip netns pids NAME       ip [-all] netns exec [NAME] cmd ...       ip netns monitor       ip netns list-id

二、ip命令的使用

创建两个名称空间并查看一下

[root@host1 ~]# ip netns add r1[root@host1 ~]# ip netns add r2

[root@host1 ~]# ip netns listr2r1

查看网络名称空间中有几个网卡

• 其实就是在网络名称空间中执行ip addr命令，需要加选项-a

• 在网络名称空间执行命令是用exec
  

[root@host1 ~]# ip netns exec r1 ip addr1: lo:  mtu 65536 qdisc noop state DOWN group default qlen 1000    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00

创建网卡对

• 用的命令是ip link
  

[root@host1 ~]# ip link helpUsage: ip link add [link DEV] [ name ] NAME                   [ txqueuelen PACKETS ]                   [ address LLADDR ]                   [ broadcast LLADDR ]                   [ mtu MTU ] [index IDX ]                   [ numtxqueues QUEUE_COUNT ]                   [ numrxqueues QUEUE_COUNT ]                   type TYPE [ ARGS ]

创建一对网卡，两端分别为veth2.1和veth2.2

[root@host1 ~]# ip link add name veth2.1 type veth peer name veth2.2[root@host1 ~]# ip link show | grep veth2.*7: veth2.2@veth2.1:  mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 10008: veth2.1@veth2.2:  mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000

• type veth：指定创建的是虚拟以太网卡

为名称空间分配虚拟网卡

• 用的命令是ip link set

• 一旦将某个虚拟网卡分配到某个名称空间，在物理机中就看不到这个网卡了
  

将veth2.1保留在物理机，将veth2.2分配到r1名称空间

[root@host1 ~]# ip link set veth2.2 netns r1

[root@host1 ~]# ip netns exec r1 ip addr1: lo:  mtu 65536 qdisc noop state DOWN group default qlen 1000    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:007: veth2.2@if8:  mtu 1500 qdisc noop state DOWN group default qlen 1000    link/ether 4e:f2:68:33:47:a1 brd ff:ff:ff:ff:ff:ff link-netnsid 0

[root@host1 ~]# ip link show | grep veth2.*8: veth2.1@if7:  mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000

也可以修改虚拟网卡的名称，例如将r1中的veth2.2改名为eth0

[root@host1 ~]# ip netns exec r1 ip link set dev veth2.2 name eth0

[root@host1 ~]# ip netns exec r1 ip addr1: lo:  mtu 65536 qdisc noop state DOWN group default qlen 1000    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:007: eth0@if8:  mtu 1500 qdisc noop state DOWN group default qlen 1000    link/ether 4e:f2:68:33:47:a1 brd ff:ff:ff:ff:ff:ff link-netnsid 0

将veth2.1地址设置为10.0.0.1/8，将r1中的eth0地址地址设置为10.0.0.2/8

[root@host1 ~]# ip addr add 10.0.0.1/8 dev veth2.1

[root@host1 ~]# ip netns exec r1 ip addr add 10.0.0.2/8 dev eth0

[root@host1 ~]# ip addr show veth2.18: veth2.1@if7:  mtu 1500 qdisc noop state DOWN group default qlen 1000    link/ether 1e:62:af:a2:bc:6d brd ff:ff:ff:ff:ff:ff link-netnsid 1    inet 10.0.0.1/8 scope global veth2.1       valid_lft forever preferred_lft forever       [root@host1 ~]# ip netns exec r1 ip addr show eth07: eth0@if8:  mtu 1500 qdisc noop state DOWN group default qlen 1000    link/ether 4e:f2:68:33:47:a1 brd ff:ff:ff:ff:ff:ff link-netnsid 0    inet 10.0.0.2/8 scope global eth0       valid_lft forever preferred_lft forever

此时两个网卡都是down状态，解决方法如下

[root@host1 ~]# ip link set veth2.1 up[root@host1 ~]# ip netns exec r1 ip link set eth0 up

也可以将veth2.1放入另一个名称空间，这样两个名称空间就可以通信了

[root@host1 ~]# ip link set veth2.1 netns r2[root@host1 ~]# ip netns exec r2 ip link set veth2.1 up