[image] How to install "ifconfig" command in my ubuntu docker image?

I've just installed ubuntu docker image, when I execute "ifconfig" it says there's no such command, I tried apt-get install by there's no package named "ifconfig"(I can install some other images).

So how to do this? Thanks.

Please use the below command to get the IP address of the running container.

$ ip addr

Example-:

root@4c712d05922b:/# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
247: eth0@if248: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default
    link/ether 02:42:ac:11:00:06 brd ff:ff:ff:ff:ff:ff link-netnsid 0
    inet 172.17.0.6/16 scope global eth0
       valid_lft forever preferred_lft forever
    inet6 fe80::42:acff:fe11:6/64 scope link
       valid_lft forever preferred_lft forever

write

sudo apt-get install net-tools

I came here because I was trying to use ifconfig on the container to find its IPAaddress and there was no ifconfig. If you really need ifconfig on the container go with @vishnu-narayanan answer above, however you may be able to get the information you need by using docker inspect on the host:

docker inspect <containerid>

There is lots of good stuff in the output including IPAddress of container:

"Networks": {
    "bridge": {
        "IPAMConfig": null,
        "Links": null,
        "Aliases": null,
        "NetworkID": "12345FAKEID",
        "EndpointID": "12345FAKEENDPOINTID",
        "Gateway": "172.17.0.1",
        "IPAddress": "172.17.0.3",
        "IPPrefixLen": 16,
        "IPv6Gateway": "",
        "GlobalIPv6Address": "",
        "GlobalIPv6PrefixLen": 0,
        "MacAddress": "01:02:03:04:05:06",
        "DriverOpts": null
    }
}

If Ubuntu Docker image isn't recognizing 'ifconfig' inside of GNS3, you'll need to open Ubuntu docker image on your host.

Assuming you already have docker on your host pc and ubuntu pull'd from docker images. Enter these commands in your host OS (Linux, CentOS, etc.) CLI.

$docker images

$docker run -it ubuntu

$apt-get update

$apt-get install net-tools

(side note: you can add whatever other tools and services that you would like to add now, but for now this is just to get ifconfig to work.)

$exit

Now you will commit these changes to Docker. This link for committing changes is the best summary and works (skip to Step 4):

https://phoenixnap.com/kb/how-to-commit-changes-to-docker-image#htoc-step-3-modify-the-container

When you re-open the docker image in GNS3 you should now have the ifconfig command usable and whatever other tools or services you added to the container.

Enjoy!

sudo apt-get install iproute2 then run ip addr show

it works..

You could also consider:

RUN apt-get update && apt-get install -y iputils-ping

(as Contango comments: you must first run apt-get update, to avoid error with missing repository).

See "Replacing ifconfig with ip"

it is most often recommended to move forward with the command that has replaced ifconfig. That command is ip, and it does a great job of stepping in for the out-of-date ifconfig.

But as seen in "Getting a Docker container's IP address from the host", using docker inspect can be more useful depending on your use case.

In case you want to use the Docker image as a "regular" Ubuntu installation, you can also run unminimize. This will install a lot more than ifconfig, so this might not be what you want.

From within a Dockerfile something like the following should do the trick:

RUN apt-get update && \
     apt-get install -y net-tools

From memory it's best practice to combine the update and the package installation lines to prevent docker caching the update step which can result in out-dated packages being installed.

Installing it via the CLI or a shell script:

apt-get update && apt-get install net-tools