Docker Expose Port 543

Expose Port 543 in Docker

docker run -p 543:543 your-image-name
		

This command maps container port 543 to the same port on the host machine.

Dockerfile Example

FROM node:18-alpine
WORKDIR /app
COPY . .
EXPOSE 543
CMD ["npm", "start"]
		

The EXPOSE instruction documents that the container listens on port 543.

EXPOSE vs Publish (-p)

• EXPOSE 543 documents the port inside the container.
• -p 543:543 makes the port accessible from the host.
• Exposed ports are not reachable unless published.

Docker Expose Port 543 Not Working

If Docker expose port 543 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 543 Already in Use

The error “port 543 already in use” means another process is already bound to that port on your host system.

# Find process using port 543
lsof -i :543

# OR use a different host port
docker run -p 8080:543 your-image-name
		

• Ensure your app is listening on port 543 inside the container
• Verify the port is published using -p
• Check firewall or network rules
• Avoid conflicts with existing services

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