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It changes packet routing because you're asking it to map a container port to the host public interface. How else would that occur? And what would be the point in blocking access to it?
Do you want to write routing rules, and keep track of container interfaces, and to grant access manually, for each and every port you expose?
When i have port 8888 not allowed on my firewall then no other program should 'open' that port. If i map a port with the syntax '8888:8888' exaclty that happens with docker. Not with podman.
Also this is the default syntax you will find in any guide and docs there is.
To prevent this happening with docker you will have to specify the localhost with '127.0.0.1:8888:8888'
When you check the internet for this subject you will notice that this behavior catches a lot of ppl by surpirise.
It catches people by surprise because they don't have a clue. If someone is binding to localhost just to avoid opening the firewall it means that either they don't understand how packet routing works, or that they should have used a docker network.
If you use
8888:8888it means you want the port to be open on the host's external interface. Which means it needs to be forwarded as well as accessible. Docker does this for you so you don't have to write the rules by hand, you don't have to keep track of container interfaces, and you don't have to remember to take the rules up and down whenever you start or stop the container.Out of curiosity, how do you do all this with podman? By hand?
Just alone the fact that podman, a drop in replacement for docker, does implement this in another way proofs that it is bad practice to implement the way docker did.
I am sorry. That is just bs. When i install apache and start the service and let it listen on port 80 and 443 i still have to add the firewall rule to allow it. This is the default behavior of every other programm.
When you install Apache on the host then yes, you just need a rule to allow the port. But a container runs on a separate network interface, which means you also (1) need to know the name of the interfaces involved, which change for each container and their network mode and the host's network adapter and so on, and (2) set up rules to forward the port traffic between the container interface and the host interface.
I'm guessing you haven't checked to see what Docker is actually doing, or you've looked only at the OUTPUT and INPUT chains.
I'm also guessing that when you stop Apache you leave the ports open in the firewall. Which is bad practice. Docker takes down the rules when the container stops, which ends up as better security.
I sincerely hope you're not actually running a machine that's just a firewall away from the Internet, because blaming Docker for bad security in that case is very shortsighted. Docker is actually helping you by making correct and complete firewall rules.
Yeah? How does it do that?