I use nftables to set my firewall rules. I typically manually configure the rules myself. Recently, I just happened to dump the ruleset, and, much to my surprise, my config was gone, and it was replaced with an enourmous amount of extremely cryptic firewall rules. After a quick examination of the rules, I found that it was Docker that had modified them. And after some brief research, I found a number of open issues, just like this one, of people complaining about this behaviour. I think it’s an enourmous security risk to have Docker silently do this by default.
I have heard that Podman doesn’t suffer from this issue, as it is daemonless. If that is true, I will certainly be switching from Docker to Podman.
Documentation people don’t read. People expect, that, like most other services, docker binds to ports/addresses behind the firewall. Literally no other container runtime/engine does this, including, notably, podman.
Too bad people don’t read that advice. They just deploy the webtop docker compose, without understanding what any of it is. I like (hate?) linuxserver’s webtop, because it’s an example of the two of the worst footguns in docker in one
To include the rest of my comment that I linked to:
You originally stated:
And I’m trying to say that even if that was true, it would still be better than a footgun where people expose stuff that’s not supposed to be exposed.
But that isn’t the case for podman. A quick look through the github issues for podman, and I don’t see it inundated with newbies asking “how to expose services?” because they assume the firewall port needs to be opened, probably. Instead, there are bug reports in the opposite direction, like this one, where services are being exposed despite the firewall being up.
(I don’t have anything against you, I just really hate the way docker does things.)
Sure, I get it, this stuff should be accessible for all. Easy to use with sane defaults and all that. But at the end of the day anyone wanting to using this stuff is exposing potential/actual vulnerabilites to the internet (via the OS, the software stack, the configuration, … ad nauseum), and the management and ultimate responsibility for that falls on their shoulders.
If they’re not doing the absolute minimum of R’ingTFM for something as complex as Docker then what else has been missed?
Unless you tell it otherwise that’s exactly what it does. If you don’t bind ports good luck accessing your NAT’d 172.17.0.x:3001 service from the internet. Podman has the exact same functionality.