Docker Expose Port 811

Expose Port 811 in Docker

docker run -p 811:811 your-image-name
		

This command maps container port 811 to the same port on the host machine.

Dockerfile Example

FROM node:18-alpine
WORKDIR /app
COPY . .
EXPOSE 811
CMD ["npm", "start"]
		

The EXPOSE instruction documents that the container listens on port 811.

EXPOSE vs Publish (-p)

• EXPOSE 811 documents the port inside the container.
• -p 811:811 makes the port accessible from the host.
• Exposed ports are not reachable unless published.

Docker Expose Port 811 Not Working

If Docker expose port 811 is not working, it is usually due to incorrect port publishing, an application not listening on the expected port, or a port conflict on the host machine.

Port 811 Already in Use

The error “port 811 already in use” means another process is already bound to that port on your host system.

# Find process using port 811
lsof -i :811

# OR use a different host port
docker run -p 8080:811 your-image-name
		

• Ensure your app is listening on port 811 inside the container
• Verify the port is published using -p
• Check firewall or network rules
• Avoid conflicts with existing services

Related Docker Expose Port Guides