Restrict Internet Access - Docker Container

Question

I have a situation to restrict internet access of the container in load balancer network. for example in that below picture

Only container4

Answer 1

Network creation for access internet

docker network create --subnet=172.19.0.0/16 internet

Network creation for block internet access

docker network create --internal --subnet 10.1.1.0/24 no-internet

If you want to connect docker container into internet

docker network connect internet container-name

If you want to block internet access

docker network connect no-internet container-name

Note

in internal network we can't expose ports to connect outside world, please refer this question for more details

Answer 2

As found here, I got this to work with docker-compose. Save as docker-compose.yml:

version: '3'

services:
  outgoing-wont-work:
    image: alpine
    networks:
      - no-internet
    command: ping -c 3 google.com # will crash

  internal-will-work:
    image: alpine
    networks:
      - no-internet
    command: ping -c 3 internal-and-external

  internal-and-external:
    image: alpine
    networks:
      - no-internet
      - internet
    command: ping -c 3 google.com

networks:
  no-internet:
    driver: bridge
    internal: true
  internet:
    driver: bridge

Then run docker-compose up -d, docker-compose ps will show something like this after a few seconds:

              Name                            Command               State    Ports
----------------------------------------------------------------------------------
dco_inet_internal-and-external_1   ping -c 3 google.com             Exit 0        
dco_inet_internal-will-work_1      ping -c 3 internal-and-ext ...   Exit 0        
dco_inet_outgoing-wont-work_1      ping -c 3 google.com             Exit 1      

Answer 3

As stated in Bilal's answer, the internal network is a good solution if you do not need to expose the ports.

If you do need to expose the ports, the below solution using iptables does the job for my requirements:

docker network create --subnet 172.19.0.0/16 no-internet
sudo iptables --insert DOCKER-USER -s 172.19.0.0/16 -j REJECT --reject-with icmp-port-unreachable
sudo iptables --insert DOCKER-USER -s 172.19.0.0/16 -m state --state RELATED,ESTABLISHED -j RETURN

Then add

--network no-internet

when you run your docker container. For instance:

$ docker run -it --network no-internet ubuntu:focal /bin/bash
root@9f2181f79985:/# apt update
Err:1 http://archive.ubuntu.com/ubuntu focal InRelease
  Temporary failure resolving 'archive.ubuntu.com'

Answer 4

Another option, if you need to expose ports on a container without internet access, but want to let it talk to other containers would be to provide a bogus DNS configuration. This isn't a perfect solution though, since it doesn't prevent direct IP access to the outside world.

docker-compose.yaml

version: '3'

services:
  service1:
    image: alpine
    command: sh -c 'ping service2 -c 1; ping google.com -c 1'
    dns: 0.0.0.0
  service2:
    image: alpine
    command: sh -c 'ping service1 -c 1; ping google.com -c 1'
    dns: 0.0.0.0

isolated> docker-compose up
Recreating isolated_service1_1 ... done                                                                                 Recreating isolated_service2_1 ... done                                                                                 Attaching to isolated_service2_1, isolated_service1_1
service1_1  | PING service2 (172.18.0.2) 56(84) bytes of data.
service1_1  | 64 bytes from isolated_service2_1.isolated_default (172.18.0.2): icmp_seq=1 ttl=64 time=0.038 ms
service1_1  |
service1_1  | --- service2 ping statistics ---
service1_1  | 1 packets transmitted, 1 received, 0% packet loss, time 0ms
service1_1  | rtt min/avg/max/mdev = 0.038/0.038/0.038/0.000 ms
service2_1  | PING service1 (172.18.0.3) 56(84) bytes of data.
service2_1  | 64 bytes from isolated_service1_1.isolated_default (172.18.0.3): icmp_seq=1 ttl=64 time=0.093 ms
service2_1  |
service2_1  | --- service1 ping statistics ---
service2_1  | 1 packets transmitted, 1 received, 0% packet loss, time 0ms
service2_1  | rtt min/avg/max/mdev = 0.093/0.093/0.093/0.000 ms
service1_1  | ping: google.com: Temporary failure in name resolution
service2_1  | ping: google.com: Temporary failure in name resolution
isolated_service1_1 exited with code 2
isolated_service2_1 exited with code 2