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PSA: Docker nukes your firewall rules and replaces them with its own. (sh.itjust.works)

submitted 8 months ago* (last edited 8 months ago) by Kalcifer@sh.itjust.works to c/selfhosted@lemmy.world

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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.

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[-] null@slrpnk.net 3 points 8 months ago

My solution to this has been to not forward the ports on individual services at all. I put a reverse proxy in front of them, refer to them by container name in the reverse proxy settings, and make sure they're on the same docker network.

this post was submitted on 11 Mar 2024

213 points (90.5% liked)

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