- Host-system: Debian 5.8.0-0.bpo.2-amd64
- Docker: 19.03.13, build 4484c46d9d
- Host IP: 192.168.1.21 {I sit on the same subnet.}
- Host Interface: ens192
- Goal: From my PC(192.168.1.x) connect to the host(192.168.1.21) via port 81 to access WebGUI for OMV. Docker iptables rules are causing a problem.
I’m running OpenMediaVault 5.x with Docker on the host machine and was able to access the OpenMediaVault WebGUI through 192.168.1.21:80.
To avoid conflict with a container that needs to use port 443 and 80, I switched the OMV WebGUI port to 81. Now I only get refused connection when I try to connect to said WebGUI.
I read throught the documentation and found I need to use DOCKER-USER to set up my own iptables rules, but I am at lost here what to configure in DOCKER-USER. Here is the iptables-save output
*nat
:PREROUTING ACCEPT [0:0]
:INPUT ACCEPT [0:0]
:POSTROUTING ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
:DOCKER - [0:0]
-A PREROUTING -m addrtype --dst-type LOCAL -j DOCKER
-A POSTROUTING -s 172.17.0.0/16 ! -o docker0 -j MASQUERADE
-A POSTROUTING -s 172.18.0.0/16 ! -o br-94326f21ec35 -j MASQUERADE
-A POSTROUTING -s 172.17.0.2/32 -d 172.17.0.2/32 -p tcp -m tcp --dport 9000 -j MASQUERADE
-A POSTROUTING -s 172.18.0.2/32 -d 172.18.0.2/32 -p tcp -m tcp --dport 443 -j MASQUERADE
-A POSTROUTING -s 172.17.0.2/32 -d 172.17.0.2/32 -p tcp -m tcp --dport 8000 -j MASQUERADE
-A POSTROUTING -s 172.18.0.2/32 -d 172.18.0.2/32 -p tcp -m tcp --dport 80 -j MASQUERADE
-A OUTPUT ! -d 127.0.0.0/8 -m addrtype --dst-type LOCAL -j DOCKER
-A DOCKER -i docker0 -j RETURN
-A DOCKER -i br-94326f21ec35 -j RETURN
-A DOCKER ! -i docker0 -p tcp -m tcp --dport 9000 -j DNAT --to-destination 172.17.0.2:9000
-A DOCKER ! -i br-94326f21ec35 -p tcp -m tcp --dport 443 -j DNAT --to-destination 172.18.0.2:443
-A DOCKER ! -i docker0 -p tcp -m tcp --dport 8000 -j DNAT --to-destination 172.17.0.2:8000
-A DOCKER ! -i br-94326f21ec35 -p tcp -m tcp --dport 80 -j DNAT --to-destination 172.18.0.2:80
COMMIT
Completed on Wed Nov 18 10:28:22 2020
Generated by xtables-save v1.8.2 on Wed Nov 18 10:28:22 2020
*filter
:INPUT ACCEPT [0:0]
:FORWARD DROP [0:0]
:OUTPUT ACCEPT [0:0]
:DOCKER - [0:0]
:DOCKER-ISOLATION-STAGE-1 - [0:0]
:DOCKER-ISOLATION-STAGE-2 - [0:0]
:DOCKER-USER - [0:0]
-A FORWARD -j DOCKER-USER
-A FORWARD -j DOCKER-ISOLATION-STAGE-1
-A FORWARD -o docker0 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -o docker0 -j DOCKER
-A FORWARD -i docker0 ! -o docker0 -j ACCEPT
-A FORWARD -i docker0 -o docker0 -j ACCEPT
-A FORWARD -o br-94326f21ec35 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -o br-94326f21ec35 -j DOCKER
-A FORWARD -i br-94326f21ec35 ! -o br-94326f21ec35 -j ACCEPT
-A FORWARD -i br-94326f21ec35 -o br-94326f21ec35 -j ACCEPT
-A DOCKER -d 172.17.0.2/32 ! -i docker0 -o docker0 -p tcp -m tcp --dport 9000 -j ACCEPT
-A DOCKER -d 172.18.0.2/32 ! -i br-94326f21ec35 -o br-94326f21ec35 -p tcp -m tcp --dport 443 -j ACCEPT
-A DOCKER -d 172.17.0.2/32 ! -i docker0 -o docker0 -p tcp -m tcp --dport 8000 -j ACCEPT
-A DOCKER -d 172.18.0.2/32 ! -i br-94326f21ec35 -o br-94326f21ec35 -p tcp -m tcp --dport 80 -j ACCEPT
-A DOCKER-ISOLATION-STAGE-1 -i docker0 ! -o docker0 -j DOCKER-ISOLATION-STAGE-2
-A DOCKER-ISOLATION-STAGE-1 -i br-94326f21ec35 ! -o br-94326f21ec35 -j DOCKER-ISOLATION-STAGE-2
-A DOCKER-ISOLATION-STAGE-1 -j RETURN
-A DOCKER-ISOLATION-STAGE-2 -o docker0 -j DROP
-A DOCKER-ISOLATION-STAGE-2 -o br-94326f21ec35 -j DROP
-A DOCKER-ISOLATION-STAGE-2 -j RETURN
-A DOCKER-USER -j RETURN
COMMIT
Thanks in advance.