添加veth-pair对
# 查看此时网络设备[root@boy ~]# ip link show1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:002: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000link/ether 00:0c:29:4c:30:4e brd ff:ff:ff:ff:ff:ff# 添加网桥设备br0[root@boy ~]# ip link add br0 type bridge# 添加veth设备对[root@boy ~]# ip link add veth1 type veth peer name veth2# 将veth1绑定到br0[root@boy ~]# ip link set veth1 master br0
通过下面可以发现，在未将veth2添加到namespace时，veth1@veth2表示：veth1接口的对端接口名称为：veth2
[root@boy ~]# ip link show1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:002: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000link/ether 00:0c:29:4c:30:4e brd ff:ff:ff:ff:ff:ff3: br0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000link/ether 82:65:dc:57:ed:39 brd ff:ff:ff:ff:ff:ff4: veth2@veth1: <BROADCAST,MULTICAST,M-DOWN> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000link/ether 2a:ce:91:42:45:66 brd ff:ff:ff:ff:ff:ff5: veth1@veth2: <BROADCAST,MULTICAST,M-DOWN> mtu 1500 qdisc noop master br0 state DOWN mode DEFAULT group default qlen 1000link/ether 82:65:dc:57:ed:39 brd ff:ff:ff:ff:ff:ff
通过下面可以发现，当我们把veth2加入test namespace后，veth2对主机不可见，宿主机内veth1@veth2 -> veth1@if4，test namespace内 veth2@if5
# 将veth2 添加到一个namespace[root@boy ~]# ip netns add test[root@boy ~]# ip link set veth2 netns test# 查看网络设备[root@boy ~]# ip link show type veth5: veth1@if4: <BROADCAST,MULTICAST> mtu 1500 qdisc noop master br0 state DOWN mode DEFAULT group default qlen 1000link/ether 82:65:dc:57:ed:39 brd ff:ff:ff:ff:ff:ff link-netnsid 0# test命名空间查看网络设备[root@boy ~]# ip netns exec test ip link show1: lo: <LOOPBACK> mtu 65536 qdisc noop state DOWN mode DEFAULT group default qlen 1000link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:004: veth2@if5: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000link/ether 2a:ce:91:42:45:66 brd ff:ff:ff:ff:ff:ff link-netnsid 0
那么在容器内或者宿主机如何确定veth对端接口？
# 方法一， x: 网卡名 x表示index5: veth1@if4 # 表示当前网卡index为5,其对端index为44: veth2@if5 # 表示当前网卡index为4，其对端index为5# 方法二查看网卡index: /sys/class/net/<interface>/ifindex查看对端网卡index：/sys/class/net/<interface>/iflink
Docker环境
# 查看网卡设备root@Y7000P:~# ip link show1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:002: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP mode DEFAULT group default qlen 1000link/ether 00:0c:29:c0:67:c4 brd ff:ff:ff:ff:ff:ffaltname enp2s13: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN mode DEFAULT group default link/ether 02:42:fd:3d:e8:0a brd ff:ff:ff:ff:ff:ff# 运行busybox，默认使用bridge网络模式root@Y7000P:~# docker run -d --name busybox busybox:1.28 sleep 10000eb8ddff7153f8af7431f35d674a2047b0b7e2375161608701acccb1fef2915e0# 宿主机查看网络设备root@Y7000P:~# ip link show1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:002: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP mode DEFAULT group default qlen 1000link/ether 00:0c:29:c0:67:c4 brd ff:ff:ff:ff:ff:ffaltname enp2s13: docker0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP mode DEFAULT group default link/ether 02:42:fd:3d:e8:0a brd ff:ff:ff:ff:ff:ff15: vethe120a64@if14: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master docker0 state UP mode DEFAULT group default link/ether d2:32:50:64:e7:bc brd ff:ff:ff:ff:ff:ff link-netnsid 0root@Y7000P:~# docker exec busybox ip link show1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue qlen 1000link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:0014: eth0@if15: <BROADCAST,MULTICAST,UP,LOWER_UP,M-DOWN> mtu 1500 qdisc noqueue link/ether 02:42:ac:11:00:02 brd ff:ff:ff:ff:ff:ff
可以发现在容器内只需要找到宿主机index 15的网卡（即为容器的对端网卡）
