Docker Container Socker Error NIC

General
1

So, what is happening is we have a python socket script which is trying to bind a nic from the host machine to the socket, but we are running the container as the non-root because of security reason and even after adding --cap-add=NET_RAW and --cap-add=NET_ADMIN the socker binding to the interface is giving error cannot bind requires root privileges any idea about this ?

2

It is hard to say anything based on the description as we don’t know the exact error message or the context, when and where you saw that message and what throws that message. If something requires root privileges in the container, it doesn’t matter what capabilities you set, it just removes restrictions that you wouldn’t have outside the container either. So can you tell more about the tool you are using in the container and what exactly gave you the error message and what it was? I assume the end of your previous message is almost the error message but any small detail could matter that is missing from the original one.

3

Thanks for replying. We are trying to run a python script which uses the socket module to bind the socket to an NIC so that we can send packets using that NIC and in docker run we are passing the user also --user user:group but when we run the script the socket throws an error “unable to bind interface (root privileges required)”. Now the thing is as you told even if you add capabilities, it will not matter. After running as root user, it works but due to security reason we don’t want to run as root. I tried to find a way if there is to run but nothing worked like --privileged flag and --cap-add flags. So, is there any other way to make the socket bind to interface without running the container as root? Can we do something like giving the user we are running in the docker container the networking privilege something like that or any other better way.

Btw thanks a lot.

4

We had a topic about this in the past: Adding capabilities to containers running as non-root users - #2 by matinats

I didn’t test it myself.

The pihole image seem to implement a solution for it. You could study it and find out how they do it: https://github.com/pi-hole/docker-pi-hole?tab=readme-ov-file#note-on-capabilities.

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5

thanks a lot @meyay will go through it. Will see if it works

6

Please share your final solution if things work out, so others can benefit from it as well :slight_smile:

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7

Hi @meyay I tested the solution in the topic you shared that worked. Thanks a lot for sharing that first of all.

The other solution pihole I could not test because it’s kind of complex than the above solution and also it had a blocker that it supports only some distros so don’t know about this solution.

So, I just want to explain what I think about the first solution. When we try to add --cap-add in the docker run it will try to add capability but the user running inside will be non-root so will not get the capability. But when you add that setcap in the .dockerfile what happens is the docker built is run by a root account or user which can set the capability for the container that could be a specific command like chown or an executable like python. So, using this solution you can solve the problem of not running the container as root but still give a specific privilege to a process or whatever.

Btw thanks all for all the replies.

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8

That you for sharing your solution, and explaining it as well! :slight_smile:

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