How to Fix Docker Driver Failed Programming External Connectivity
Quick Fix Summary
TL;DRRestart Docker daemon and flush iptables rules to resolve immediate network driver conflicts.
This error occurs when Docker's network driver (typically `bridge`) fails to program the necessary iptables rules for external connectivity, such as port mapping or container-to-host communication. It's a critical failure that prevents containers from being accessible from outside the host.
Diagnosis & Causes
Recovery Steps
Step 1: Immediate Daemon Restart & Network Reset
First, attempt to reset Docker's networking state. This flushes Docker-managed iptables rules and restarts the core networking components.
# Stop all containers and the Docker service
sudo docker stop $(docker ps -aq)
sudo systemctl stop docker
# Flush Docker's iptables chains (DOCKER, DOCKER-ISOLATION)
sudo iptables -t nat -F
sudo iptables -t filter -F DOCKER
sudo iptables -t filter -F DOCKER-ISOLATION
# Restart Docker daemon
sudo systemctl start dockerStep 2: Resolve Firewall Conflicts (firewalld/ufw)
If using firewalld or ufw, they can interfere with Docker's iptables rules. Configure them to allow Docker to manage its own chains.
# For systems with firewalld:
sudo systemctl stop firewalld
sudo systemctl disable firewalld
# OR, to coexist, add Docker zone and reload (RHEL/CentOS/Fedora)
sudo firewall-cmd --permanent --zone=trusted --add-interface=docker0
sudo firewall-cmd --permanent --zone=trusted --add-port=4243/tcp
sudo firewall-cmd --reload
# For systems with ufw (Ubuntu/Debian): Ensure forwarding is allowed
sudo sed -i -e 's/DEFAULT_FORWARD_POLICY="DROP"/DEFAULT_FORWARD_POLICY="ACCEPT"/g' /etc/default/ufw
sudo ufw reloadStep 3: Recreate Default Docker Networks
If the bridge network is corrupted, delete and let Docker recreate it. This is a non-destructive operation for user-defined networks.
# Disconnect all containers from the default bridge network
for container in $(docker ps -q); do
docker network disconnect -f bridge $container
done
# Remove the corrupted bridge network
sudo docker network rm bridge
# Restart Docker to auto-recreate the default networks
sudo systemctl restart docker
# Verify the bridge network is back
docker network ls | grep bridgeStep 4: Verify Kernel Modules & Docker Configuration
Ensure required kernel modules are loaded and Docker's daemon.json is correctly configured for iptables.
# Load essential kernel modules
sudo modprobe iptable_nat
sudo modprobe br_netfilter
# Check Docker daemon configuration
cat /etc/docker/daemon.json
# Ensure it contains (create if missing):
{
"iptables": true,
"ip-masq": true
}
# Apply config and restart
sudo systemctl restart dockerArchitect's Pro Tip
"In Kubernetes-on-Docker setups, kube-proxy can lock iptables. Use `iptables -w` flag in Docker 20.10+ via `daemon.json` with `"iptables": true` to prevent race conditions."
Frequently Asked Questions
Will flushing iptables disrupt other services on my server?
Yes. Flushing nat and filter tables will drop all firewall and NAT rules. This is a last-resort, production-impacting step. Always note rules with `iptables-save` first and restore them if the Docker fix doesn't work.
How do I prevent this error from recurring?
Ensure no other process (like a manual firewall script, VPN software, or another container runtime) modifies iptables after Docker starts. Set `"iptables": true` in `/etc/docker/daemon.json` and avoid stopping Docker if custom rules are present.
I'm using Docker Desktop (Mac/Windows). Does this apply?
The core cause is similar, but the fix differs. For Docker Desktop, use the GUI: Troubleshoot > Reset to factory defaults. This recreates the virtual machine's networking stack.