zlacker

>>todsac+(OP)
Docker has a known security issue with port exposure in that it punches holes through the firewall without asking your permission, see https://github.com/moby/moby/issues/4737

I usually expose ports like `127.0.0.1:1234:1234` instead of `1234:1234`. As far as I understand, it still punches holes this way but to access the container, an attacker would need to get a packet routed to the host with a spoofed IP SRC set to `127.0.0.1`. All other solutions that are better seem to be much more involved.

>>smarx0+P4
This is only an issue if you run Docker on your firewall, which you absolutely should not.

>>globul+V5
Ideally, yes. But in reality, this means that if you just want to have 1 little EC2 VM on AWS running Docker, you now need to create a VM, a VPC, an NLB/ALB in front of the VPC ($20/mo+, right?) and assign a public IP address to that LB instead. For a VM like t4g.nano, it could mean going from a $3/mo bill to $23/mo ($35 in case of a NAT gateway instead of an LB?) bill, not to mention the hassle of all that setup. Hetzner, on the other hand, has a free firewall included.

>>smarx0+K6
There's no good reason a VM or container on Hetzner cannot use a firewall like IPTables. If that makes the service too expensive you increase cost or otherwise lower resources. A firewall is a very simple, essential part of network security. Every simple IoT device running Linux can run IPTables, too.

>>Fnoord+B7
I guess you did not read the link I posted initially. When you set up a firewall on a machine to block all incoming traffic on all ports except 443 and then run docker compose exposing port 8000:8000 and put a reverse proxy like caddy/nginx in front (e.g. if you want to host multiple services on one IP over HTTPS), Docker punches holes in the iptables config without your permission, making both ports 443 and 8000 open on your machine.

@globular-toast was not suggesting an iptables setup on a VM, instead they are suggesting to have a firewall on a totally different device/VM than the one running docker. Sure, you can do that with iptables and /proc/sys/net/ipv4/ip_forward (see https://serverfault.com/questions/564866/how-to-set-up-linux...) but that's a whole new level of complexity for someone who is not an experienced network admin (plus you now need to pay for 2 VMs and keep them both patched).