I’ve recently learned that UFW firewall rules do not affect Docker containers. I am looking into learning firewall rules in depth but in the meantime I want make sure I don’t fuck something up, so here are a few questions:
1- On a host that drops all incoming connections (configured through UFW), if I have a container with only a single port mapping 127.0.0.1:8080:80 is there any way to access this container through the public internet, what about 8080:80 or no port mapping at all?
2- How do I drop all incoming connections to all Docker containers and do I need to do that? Similar to ufw default deny incoming?
3- Is there a way to see all incoming/outgoing connections of all containers?
Thanks in advance and any resource advice for securing docker for dummies is appreciated.
Oh boy I went down this same rabbit hole awhile ago. Here is a git repository that will explain why this happens and also offers a fix on how to modify your IP tables to ensure that docker respects the UFW.
I too read that it didn’t work with docker but that was not my experience on Ubuntu 24.04. Maybe it’s just docker desktop but I had all sorts of other issues with docker desktop and ditched it for plain docker, using lazydocker for an interface. I think one of the issues for outgoing connections at least is that IPs for the containers can change. I don’t remember exactly what my setup is currently but you shouldn’t have an issue opening up just specific ports mapped to a container while having default deny incoming. Not specific to containers but there are a few different Linux commands to get all ports and the processes listening on them, I used them extensively to debug my firewall setup. I can’t remember them either off the top of my head but you should be able to google for your distro.
To add, you may not need to worry too much about setting up a firewall if your machine is behind a router/gateway that also has a firewall. There are arguments both ways, I would suggest researching that some. I did it because I could so why not, but I also only have wireguard exposed publicly so it may be over kill
Try tailscale for remote acess run it as a docker container. I csnt help you with the other questions.
It’s not about docker. Just read up on networking.
telling someone asking these questions to read up on networking is the same as telling someone who’s asking why they can’t fly in the air to “just” read up on physics
Then maybe you’re not equipped to be attempting this. It’s basic networking.
If I ask and invite an electrician out to my house and proceed to tell him how I can just do it all myself, I deserve the horrible outcome.
DF.
I think the important factor is that you have contributed nothing of value to help this person learn. You could have linked to a useful resources, you have suggested Google searches to point in the correct direction. But you basically said “This is easy, RTFM”. Next time at least send them the manual they should read.
I pointed them right to the problem. Please explain how that isn’t helping?
Let’s say that yes, you pointed them to “networking”. The issue is that they have a specific problem and you are pointing to a topic so broad and deep with no specific direction. But you also say “it’s basic”. Well if it truly is basic and they still don’t get it, this would be a clear indication that they need some level of hand holding. Last if your feeling “that is a lot of work, I don’t want to do that” no problem you don’t have to. But in that that situation I would suggest reviewing before commenting: is it going to get the person closer to a solution? Is encouraging to the person? Am I indicating I also have this problem indicating someone else could step in and help multiple people at once? Is it funny? If it’s no on all those, maybe don’t comment.