Can't get it running on linux

[RobertHeim]

I am trying to use the bridged network d_backend to communicate between nc listening on the host service and a docker container emitting messages.

This is the network

$ sudo docker network ls
NETWORK ID          NAME                DRIVER              SCOPE
fdc454526116        d_backend           bridge              local

$ sudo docker network inspect d_backend --format='{{( index .IPAM.Config 0).Gateway}}'
172.22.0.1

On the host I bind nc to that ip:

nc 172.22.0.1 2323 -lk

This is my docker-compose.yml

version: '3.5'

services:

  dockerhost:
    image: qoomon/docker-host
    cap_add:
      - NET_ADMIN
      - NET_RAW
    restart: on-failure
    networks:
      - backend

  tcp_message_emitter:
    image: alpine
    depends_on:
      - dockerhost
    command: [ "sh", "-c", "while :; do date; sleep 1; done | nc 'dockerhost' 2323 -v"]
    networks:
      - backend

networks:
  backend:
    driver: bridge

I run this (within folder d so that the correct network is used)

/home/foo/d$ sudo docker-compose up
Starting d_dockerhost_1 ... done
Starting d_tcp_message_emitter_1 ... done
Attaching to d_dockerhost_1, d_tcp_message_emitter_1
dockerhost_1           | Docker Host: 172.22.0.1 (default gateway)

I would expect to see a date on the host every second, but I don't. Any ideas?

[RobertHeim]

It is a firewall issue. The host firewall must allow the dockerhost container to access the relevant port.

Get the relevant port of the container:

sudo docker inspect -f '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' d_dockerhost_1
172.22.0.2

Allow the container's ip to access the port on the host, here using ufw:

sudo ufw allow from 172.22.0.2 proto tcp to any port 2323

done :)

[qoomon]

glad to here that.

[meijieru]

@qoomon Could you please update the README for a more general command? I still mess up with the command.

[qoomon]

What kind of example you are thinking of?

…

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