ip netns
虚拟化网络都是基于netns实现
ip-netns - process network namespace management #管理网络名称空间工具
网络命名空间在逻辑上是网络堆栈的另一个副本，具有自己的路由，防火墙规则和网络设备。 默认情况下，进程从其父级继承其网络命名空间。最初，所有进程共享相同的默认网络名称空间 来自init进程。
SYNOPSIS top #用法
ip [ OPTIONS ] netns { COMMAND | help }
ip netns [ list ] #列出所有名称空间
ip netns add NETNSNAME #创建一个新的名称空间
ip netns attach NETNSNAME PID
ip [-all] netns del [ NETNSNAME ] #伤处一个名称空间
ip netns set NETNSNAME NETNSID
ip netns identify [ PID ]
ip netns pids NETNSNAME
ip [-all] netns exec [ NETNSNAME ] command... #在网络名称空间执行指定命令
ip netns monitor
ip netns list-id
ip [-all] netns delete [ NAME ] - delete the name of a network namespace(s)
[root@localhost netreport]# ip netns add testspace #添加一个名称空间
[root@localhost netreport]# ip netns list #列出
testspace
[root@localhost netreport]# ip netns del testspace #删除
[root@localhost netreport]# ip netns add testspace
[root@localhost netreport]# ip netns exec testspace ifconfig -a #执行命令
lo: flags=8<LOOPBACK> mtu 65536
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 netreport]#
ip-link: network device configuration
#ip link 网络设备管理工具，用于配置虚拟网卡
[root@localhost netreport]# ip link help Usage: 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 ] ip link delete { DEVICE | dev DEVICE | group DEVGROUP } type TYPE [ ARGS ] ip link set { DEVICE | dev DEVICE | group DEVGROUP } [ { up | down } ] [ type TYPE ARGS ] [ arp { on | off } ] [ dynamic { on | off } ] [ multicast { on | off } ] [ allmulticast { on | off } ] [ promisc { on | off } ] [ trailers { on | off } ] [ carrier { on | off } ] [ txqueuelen PACKETS ] [ name NEWNAME ] [ address LLADDR ] [ broadcast LLADDR ] [ mtu MTU ] [ netns { PID | NAME } ] [ link-netnsid ID ] [ alias NAME ] [ vf NUM [ mac LLADDR ] [ vlan VLANID [ qos VLAN-QOS ] [ proto VLAN-PROTO ] ] [ rate TXRATE ] [ max_tx_rate TXRATE ] [ min_tx_rate TXRATE ] [ spoofchk { on | off} ] [ query_rss { on | off} ] [ state { auto | enable | disable} ] ] [ trust { on | off} ] ] [ node_guid { eui64 } ] [ port_guid { eui64 } ] [ xdp { off | object FILE [ section NAME ] [ verbose ] | pinned FILE } ] [ master DEVICE ][ vrf NAME ] [ nomaster ] [ addrgenmode { eui64 | none | stable_secret | random } ] [ protodown { on | off } ] ip link show [ DEVICE | group GROUP ] [up] [master DEV] [vrf NAME] [type TYPE] ip link xstats type TYPE [ ARGS ] ip link afstats [ dev DEVICE ] ip link help [ TYPE ] TYPE := { vlan | veth | vcan | dummy | ifb | macvlan | macvtap | bridge | bond | team | ipoib | ip6tnl | ipip | sit | vxlan | gre | gretap | ip6gre | ip6gretap | vti | nlmon | team_slave | bond_slave | ipvlan | geneve | bridge_slave | vrf | macsec } [root@localhost netreport]#
常用命令
ip link add - 添加虚拟链接 ip link delete - 删除虚拟链接 ip link set - 更改设备属性 ip link show - 显示设备属性 ip link xstats - 显示扩展统计信息 ip link afstats - 显示特定于地址的系列统计信息 ip link help - 显示帮助
显示设备属性
ip link show - display device attributes dev NAME：specifies the network device to show. (default) 如果不指定设备，则显示所有设备信息 up：only display running interfaces. 只显示启动的接口
添加虚拟设备
ip link add - add virtual link link DEVICE：specifies the physical device to act operate on. 指定在哪个物理设备上操作 NAME：specifies the name of the new virtual device. 指定新虚拟设备的名称 TYPE：specifies the type of the new device. 指定新设备的类型 Link types: vlan - 802.1q tagged virtual LAN interface veth - Virtual ethernet interface 虚拟网络接口（一对） vcan - Virtual Local CAN interface dummy - Dummy network interface ifb - Intermediate Functional Block device macvlan - virtual interface base on link layer address (MAC) can - Controller Area Network interface bridge - Ethernet Bridge device 网桥设备
删除虚拟设备
ip link delete - delete virtual link DEVICE：specifies the virtual device to act operate on. TYPE：specifies the type of the device. dev DEVICE：specifies the physical device to act operate on.
设置设备属性
ip link set - change device attributes
dev DEVICE：specifies network device to operate on.
up and down：change the state of the device to UP or DOWN. 启动或关闭网卡
multicast on or multicast off：change the MULTICAST flag on the device. 启用或禁用组播
name NAME：change the name of the device. 修改网卡名称。需要先donw掉网卡，不然会提示busy。
This operation is not recommended if the device is running or has some addresses already configured.
alias NAME：give the device a symbolic name for easy reference. 为网卡设置别名
mtu NUMBER：change the MTU of the device. 设置MTU大小，默认为1500
netns NETNSNAME：move the device to the network namespace associated with name NETNSNAME. 将接口移动到指定的网络名称空间
veth - Virtual ethernet interface #虚拟以太网卡
#veth设备是成对出现的，一端连接的是内核协议栈，一端彼此相连。一个设备收到协议栈的数据，会将数据发送另一个设备上去。大概结构如下：
+----------------------------------------------------------------+
| |
| +------------------------------------------------+ |
| | Newwork Protocol Stack | |
| +------------------------------------------------+ |
| ↑ ↑ ↑ |
|..............|...............|...............|.................|
| ↓ ↓ ↓ |
| +----------+ +-----------+ +-----------+ |
| | eth0 | | veth0 | | veth1 | |
| +----------+ +-----------+ +-----------+ |
|192.168.100.100 ↑ ↑ ↑ |
| | +---------------+ |
| | 10.1.1.1/24 10.1.1.2/24 |
+--------------|-------------------------------------------------+
↓
Physical Network
示例 创建一对虚拟网卡，新建的网卡默认都是关闭的，名称空间里的回环网卡lo默认也是关闭的。
[root@localhost netreport]# ip link add name veth1 type veth peer name veth2
[root@localhost netreport]# ip link show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000
link/ether 00:0c:29:8b:7c:a1 brd ff:ff:ff:ff:ff:ff
3: docker0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP mode DEFAULT group default
link/ether 02:42:3d:8c:f3:de brd ff:ff:ff:ff:ff:ff
7: vetha2d7cb7@if6: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master docker0 state UP mode DEFAULT group default
link/ether 3a:54:20:3d:ff:16 brd ff:ff:ff:ff:ff:ff link-netnsid 0
8: veth2@veth1: <BROADCAST,MULTICAST,M-DOWN> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
link/ether 8a:ed:62:73:ec:f6 brd ff:ff:ff:ff:ff:ff
9: veth1@veth2: <BROADCAST,MULTICAST,M-DOWN> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
link/ether da:6c:01:ef:3b:6a brd ff:ff:ff:ff:ff:ff
[root@localhost netreport]#
#一块网卡只能属于一个名称空间, 将veth2 网卡配置为testspace 名称空间
[root@localhost netreport]# ip link set dev veth2 netns testspace [root@localhost netreport]# ip link show 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000 link/ether 00:0c:29:8b:7c:a1 brd ff:ff:ff:ff:ff:ff 3: docker0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP mode DEFAULT group default link/ether 02:42:3d:8c:f3:de brd ff:ff:ff:ff:ff:ff 7: vetha2d7cb7@if6: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master docker0 state UP mode DEFAULT group default link/ether 3a:54:20:3d:ff:16 brd ff:ff:ff:ff:ff:ff link-netnsid 0 9: veth1@if8: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000 link/ether da:6c:01:ef:3b:6a brd ff:ff:ff:ff:ff:ff link-netnsid 1 [root@localhost netreport]#
让两块在不同名称空间网卡通信
[root@localhost netreport]# ip netns list
testspace (id: 1)
[root@localhost netreport]# ip netns exec testspace ip link set dev veth2 name veth0 #可以修改dev name
[root@localhost netreport]# ip netns exec testspace ifconfig
[root@localhost netreport]# ip netns exec testspace ifconfig -a #显示网卡
lo: flags=8<LOOPBACK> mtu 65536
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
veth0: flags=4098<BROADCAST,MULTICAST> mtu 1500
ether 8a:ed:62:73:ec:f6 txqueuelen 1000 (Ethernet)
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 netreport]# ip netns exec testspace ifconfig veth0 10.1.1.2/24
[root@localhost netreport]# ip netns exec testspace ifconfig veth0 10.1.1.2/24 up #配置名称空间网卡地址，并启动
[root@localhost netreport]# ip netns exec testspace ifconfig -a
lo: flags=8<LOOPBACK> mtu 65536
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
veth0: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500
inet 10.1.1.2 netmask 255.255.255.0 broadcast 10.1.1.255
ether 8a:ed:62:73:ec:f6 txqueuelen 1000 (Ethernet)
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 netreport]#
[root@localhost netreport]# ifconfig veth1 10.1.1.1/24
[root@localhost netreport]# ifconfig veth1 10.1.1.1/24 up #配置本地虚拟网卡地址并启动
[root@localhost netreport]# ping 10.1.1.2
PING 10.1.1.2 (10.1.1.2) 56(84) bytes of data.
64 bytes from 10.1.1.2: icmp_seq=1 ttl=64 time=0.079 ms
64 bytes from 10.1.1.2: icmp_seq=2 ttl=64 time=0.089 ms
64 bytes from 10.1.1.2: icmp_seq=3 ttl=64 time=0.067 ms
^C
--- 10.1.1.2 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 1999ms
rtt min/avg/max/mdev = 0.067/0.078/0.089/0.011 ms
[root@localhost netreport]#