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Unable to contact postgres runnign nunning on host

This is driving me nuts.
I am using rootless docker.

I have a very simple container. All it does is try to connect to a postgresql database and do a simple select.
This simple application works flawlessly outside of a container.

Inside the container it complains about unable to connect.

docker0 interface has ip and that is where I try to connect to from the container.
Simple bridged network.

netstat shows me that postgres is indeed listening on the interface and accepts the network

firewall shows that forwarding is allowed.
firewall has been configured to allow all traffic from

kernel forwarding is on

still no joy. postgresql logs connection attempts but shows nothing when running the container.

running another container and doing a shell inside the container and installing the postgresql-client also says
error: could not connect to server: Connection refused

telnet to 5432 gives no connection.

What am I doing wrong or not seeing?

Any and all hints and help is greatly appreciated.

Jeroen Baten

Other example. same result:

$ nc -l 8020 &
[1] 10835

$ docker run -ti --network=“host” alpine /bin/sh
/ # apk add curl
(1/5) Installing ca-certificates (20191127-r5)
(2/5) Installing brotli-libs (1.0.9-r3)
(3/5) Installing nghttp2-libs (1.42.0-r1)
(4/5) Installing libcurl (7.74.0-r1)
(5/5) Installing curl (7.74.0-r1)
Executing busybox-1.32.1-r2.trigger
Executing ca-certificates-20191127-r5.trigger
OK: 8 MiB in 19 packages
/ # curl localhost:8020
curl: (7) Failed to connect to localhost port 8020: Connection refused
/ #