Blog

In certain scenarios, especially when numerous Docker containers are operational within a server host, it becomes pivotal to identify the specific veth interface associated with each container. This enables us to effectively monitor the inbound and outbound traffic of individual Docker containers.

Consider a scenario with 15 active Docker containers. In such instances, determining the exact veth interface linked to a particular container proves essential for comprehensive traffic analysis and management.

madhu@myserver:~$ ip addr list | grep veth | wc -l
15

madhu@myserver:~$ sudo docker ps --format '{{.ID}}'
dcfb47b708fc
b4e72699410a
4c187a15f99d
62f7ba1f359e
88f9a3ca5751
5158fa9ff82e
6b9fc5cb32ef
b4ef57f36be8
ddb4dfc4b667
48a81371f7b5
242141c957ff
f87bc82d5ab7
3553a4f18964
26846185b81b
f607fbc8eb3c
308a1363eaf6

Each Docker container is associated with a distinct “veth” network interface, resulting in a total of 15 “veth” network interfaces for the 15 Docker containers running concurrently.

madhu@myserver:~$ ip addr list | grep veth
6: veth7948fb0@if5: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-56185a481942 state UP group default 
8: vetha1a7201@if7: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master docker0 state UP group default 
10: veth615757e@if9: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-56185a481942 state UP group default 
12: vethebb8592@if11: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master docker0 state UP group default 
16: veth740737f@if15: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-56185a481942 state UP group default 
20: veth84fc46c@if19: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-56185a481942 state UP group default 
22: veth84c7bdf@if21: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master docker0 state UP group default 
24: veth75c2a1f@if23: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-56185a481942 state UP group default 
26: veth0eac4c9@if25: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master docker0 state UP group default 
28: veth703f874@if27: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master docker0 state UP group default 
30: veth9ee258e@if29: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master docker0 state UP group default 
32: vetha9a1a85@if31: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master docker0 state UP group default 
34: vethc51f83f@if33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master docker0 state UP group default 
36: veth03fe67a@if35: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master docker0 state UP group default 
48: vethb4659b0@if47: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master docker0 state UP group default 

Get the “veth” interface ID specific to a docker container

ip addr list | grep ^$(sudo docker exec dcfb47b708fc cat /sys/class/net/eth0/iflink)

Output:

48: vethb4659b0@if47: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master docker0 state UP group default

More information about “/sys/class/net” can be found in this link