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[Solved] Docker create unknown interface on host machine

I use latest docker version on ubuntu 20.04.01

I noticed it create unknown network interface on my host machine (additional to docker0). i dont have any container that use custom network interface or i haven’t created new docker network interface (only has default bridge, host and none)

That interface disappear if i stop docker service systemctl stop docker but it reappear once it started also i uninstalled sudo apt purge docker-ce docker-ce-cli containerd.io and installed again however doesn’t solve.

how to remove that permanently?

By not starting containers :slight_smile:

Each container will get a veth interface per network it participates in.

thanks for explanation.

HI All,

I was literally new to docker. can some one tell me how to run javaws command inside docker container. I created docker container for my java application and logged into it and ran
"javaws http://ip of container:port which i exposed in docker file/rtccClient/rtcc.jnlp" it says “bash: javaws: command not found”. I create image using ibmcom/websphere-liberty:latest as base image

Docker by default supports 3 networks:

  1. None:

This mode will not configure any IP for the container and doesn’t have any access to the external network as well as for other containers. It does have the loopback address and can be used for running batch jobs.

docker run -it --network=none ubuntu:14.04 /bin/bash

root@66308c6686be:/# ifconfig
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
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)

docker inspect 66308c6686be | grep -i ipaddr

        "SecondaryIPAddresses": null,
        "IPAddress": "",
                "IPAddress": "",
  1. Host

In this mode container will share the host’s network stack and all interfaces from the host will be available to the container. The container’s host name will match the host name on the host system

docker run -it --net=host ubuntu:14.04 /bin/bash

root@labadmin-VirtualBox:/# hostname
labadmin-VirtualBox
Even the IP configuration is same as the host system’s IP configuration

root@labadmin-VirtualBox:/# ip addr | grep -A 2 eth0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
link/ether 08:00:27:b5:82:2f brd ff:ff:ff:ff:ff:ff
inet 10.0.2.15/24 brd 10.0.2.255 scope global eth0
valid_lft forever preferred_lft forever
3: lxcbr0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default
root@labadmin-VirtualBox:/# exit
exit

HOST SYSTEM IP CONFIGURATION

ip addr | grep -A 2 eth0

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
link/ether 08:00:27:b5:82:2f brd ff:ff:ff:ff:ff:ff
inet 10.0.2.15/24 brd 10.0.2.255 scope global eth0
valid_lft forever preferred_lft forever
3: lxcbr0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default
In host and none mode are not configured directly but default bridge network can be configured as well as create your own user-defined bridge networks.

  1. Bridge Mode

It is the Docker default networking mode which will enable the connectivity to the other interfaces of the host machine as well as among containers.

docker run -it --network=bridge ubuntu:14.04 /bin/bash

root@58b0b1f18b2e:/# ifconfig
eth0 Link encap:Ethernet HWaddr 02:42:ac:11:00:0c
inet addr:172.17.0.12 Bcast:0.0.0.0 Mask:255.255.0.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:16 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:2668 (2.6 KB) TX bytes:0 (0.0 B)

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
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)
Accessibility to other containers is possible in bridge mode.

root@58b0b1f18b2e:/# ping 172.17.0.11
PING 172.17.0.11 (172.17.0.11) 56(84) bytes of data.
64 bytes from 172.17.0.11: icmp_seq=1 ttl=64 time=0.143 ms
64 bytes from 172.17.0.11: icmp_seq=2 ttl=64 time=0.050 ms
Connectivity to external network.

root@58b0b1f18b2e:/# ping google.com
PING google.com (216.58.197.46) 56(84) bytes of data.
64 bytes from maa03s20-in-f46.1e100.net (216.58.197.46): icmp_seq=1 ttl=51 time=16.9 ms
Connectivity to host machine

root@labadmin-VirtualBox:~# ip a | grep eth0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
inet 10.0.2.15/24 brd 10.0.2.255 scope global eth0

root@58b0b1f18b2e:/# ping 10.0.2.15
PING 10.0.2.15 (10.0.2.15) 56(84) bytes of data.
64 bytes from 10.0.2.15: icmp_seq=1 ttl=64 time=0.113 ms