Docker Expose Port 451

Expose Port 451 in Docker

docker run -p 451:451 your-image-name
		

This command maps container port 451 to the same port on the host machine.

Dockerfile Example

FROM node:18-alpine
WORKDIR /app
COPY . .
EXPOSE 451
CMD ["npm", "start"]
		

The EXPOSE instruction documents that the container listens on port 451.

EXPOSE vs Publish (-p)

• EXPOSE 451 documents the port inside the container.
• -p 451:451 makes the port accessible from the host.
• Exposed ports are not reachable unless published.

Docker Expose Port 451 Not Working

If Docker expose port 451 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 451 Already in Use

The error “port 451 already in use” means another process is already bound to that port on your host system.

# Find process using port 451
lsof -i :451

# OR use a different host port
docker run -p 8080:451 your-image-name
		

• Ensure your app is listening on port 451 inside the container
• Verify the port is published using -p
• Check firewall or network rules
• Avoid conflicts with existing services

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