blocking port 81 with iptables DOCKER-USER doesn't work

[Mozzarella-dev]

Describe the bug

• Blocking port 81 (web panel) with iptables doesn't work and i can still access web panel from the internet. My current rule is:

iptables -I DOCKER-USER -i eth0 -p tcp --dport 81 -j DROP

Instead the webpanel takes longer to load and it's overall speed decreases, but it can be accessed from eth0 interface

• Version of Nginx Proxy Manager reported: v2.9.2

To Reproduce

• deploy the docker container with docker-compose as in the quick start guide.
• add iptable rule for the DOCKER-USER filter: sudo iptables -I DOCKER-USER -i eth0 -p tcp --dport 81 -j DROP (use eth0 if your public interface is eth0 otherwise adjust accordingly).
• test it by trying to access your_server_ip:81 from the internet.

Expected behavior
That should just block the request on port 81 as happens with other containers.

Screenshots

Operating System

• Debian 9 with:

Client: Docker Engine - Community
 Version:           19.03.15
 API version:       1.40
 Go version:        go1.13.15
 Git commit:        99e3ed8919
 Built:             Sat Jan 30 03:17:11 2021
 OS/Arch:           linux/amd64
 Experimental:      false

Server: Docker Engine - Community
 Engine:
  Version:          19.03.15
  API version:      1.40 (minimum version 1.12)
  Go version:       go1.13.15
  Git commit:       99e3ed8919
  Built:            Sat Jan 30 03:15:40 2021
  OS/Arch:          linux/amd64
  Experimental:     false
 containerd:
  Version:          1.4.3
  GitCommit:        269548fa27e0089a8b8278fc4fc781d7f65a939b
 runc:
  Version:          1.0.0-rc92
  GitCommit:        ff819c7e9184c13b7c2607fe6c30ae19403a7aff
 docker-init:
  Version:          0.18.0
  GitCommit:        fec3683

[JfrAziz]

I use this rule and it's work

sudo iptables -I DOCKER-USER -i eth0 ! -s 127.0.0.1 -p tcp --dport 81 -j DROP

it drop any request to 81 except from 127.0.0.1 or localhost, and then to access it I just use ssh tunelling from my local computer, like ssh -L 8081:127.0.0.1:81 -N -f -p 22 <user>@<ip>

[github-actions]

Issue is now considered stale. If you want to keep it open, please comment 👍

[github-actions]

Issue was closed due to inactivity.