Docker Bridge Network IP Range to CIDR

Docker Bridge Network CIDR Configuration

Docker uses bridge networks for container-to-container communication. The default bridge network uses 172.17.0.0/16, but custom bridge networks are assigned from a configurable address pool.

Default Docker Bridge

Default: 172.17.0.0 - 172.17.255.255
CIDR:    172.17.0.0/16

Docker assigns this range automatically. The gateway is typically 172.17.0.1, and containers get addresses starting from 172.17.0.2.

Custom Bridge Networks

When you create custom bridge networks, Docker allocates from its address pool:

docker network create --subnet=192.168.100.0/24 my-network

Docker Daemon Address Pool

Configure the address pool in /etc/docker/daemon.json:

{
  "default-address-pools": [
    {"base": "10.10.0.0/16", "size": 24}
  ]
}

This tells Docker to allocate /24 subnets from the 10.10.0.0/16 range.

Common Docker CIDR Conflicts

Docker's default 172.17.0.0/16 can conflict with:

Service	Common Range
AWS default VPC	172.31.0.0/16
Corporate VPN	172.16.0.0/12
Other Docker hosts	172.17-172.31.0.0/16

Docker Compose Networking

networks:
  backend:
    driver: bridge
    ipam:
      config:
        - subnet: 10.20.0.0/24
          gateway: 10.20.0.1

Troubleshooting Range Conflicts

When Docker's range overlaps with your VPN or cloud network:

1. Identify the conflicting ranges
2. Convert both to CIDR using this tool
3. Check for overlap
4. Reconfigure Docker's address pool to use a non-overlapping range