Context
I want to host public-facing applications on a server in my home, without compromising security. I realize containers might be one way to do this, and want to explore that route further.
Requirements
I want to run applications within containers such that they
- Must not be able to interfere with applications running on host
- Must not be able to interfere with other containers or applications inside them
- Must have no access or influence on other devices in the local network, or otherwise compromise the security of the network, but still accessible by devices via ssh.
Note: all of this within reason. I understand that sometimes there may be occasional vulnerabilities, like in kernel for example, that would eventually get fixed. Risks like this within reason I am willing to accept.
What I found so far
- Running containers in rootless mode: in other words, running the container daemon with an unprivileged host user
- Running applications in container under unprivileged users: the container user under which the container is ran should be unprivileged
- Networking: The container’s networking must be restricted. I am still not sure how to do this and shall explore it more, but would appreciate any resources.
Alternative solution
I have seen bubblewrap presented as an alternative, but it seems like it is not intended to be used directly in this manner, and information about using it for this is scarce.
Both Docker and Podman pretty much handle all of those so I think you’re good. The last aspect about networking can easily be fixed with a few iptables/nftables/firewalld rules. One final addition could be NGINX in front of web services or something dedicated to handling web requests on the open Internet to reduce potential exploits in the embedded web servers in your apps. But other than that, you’ve got it all covered yourself.
There’s all the options needed to limit CPU usage, memory usage or generally prevent using up all the system’s resources in docker/podman-compose files as well.
If you want an additional layer of security, you could also run it all in a VM, so a container escape leads to a VM that does nothing else but run containers. So another major layer to break.