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8084

Port 8084 – WEBrick / DevServer

TCP

Port 8084 is used by various development web servers and admin interfaces when lower ports are occupied. Jenkins build agents, CICS web interface, and some microservice frameworks use 8084 as an alternate HTTP port. No special security properties – same precautions as any development HTTP port.

Port Number

8084

Protocol

TCP

Service

HTTP Development Alternate

Range

IANA Registered (1024–49151)

Description

Port 8084 serves as a generic alternate HTTP port when applications need multiple services on one host. It appears in Jenkins agent configurations, IBM CICS web interfaces, and development environments running multiple microservices locally. In microservice development (docker-compose with 5+ services), ports like 8084 get assigned sequentially to avoid conflicts. Ensure development ports bind to 127.0.0.1 and use a reverse proxy with TLS for any service that needs external access.

Security risks

  • 1Development server exposure: services on 8084 are often secondary instances with debug endpoints, health checks exposing internal state, or admin APIs without authentication. Bind to 127.0.0.1 explicitly.
  • 2Docker port mapping oversight: docker-compose files mapping -p 8084:80 bind to 0.0.0.0 by default, exposing internal services to the host network. Use 127.0.0.1:8084:80.
  • 3Proxy bypass: if a reverse proxy on port 443 enforces auth, direct access to port 8084 bypasses those controls entirely. Ensure backend ports are unreachable from external networks.

Firewall guidance

Block inbound 8084 from the internet. In development, bind to 127.0.0.1 explicitly. In production, use a reverse proxy (Nginx/Caddy on 443) with TLS termination forwarding to 8084 on localhost.

Diagnosis commands

Identify which process owns port 8084

shell
ss -tnlp sport = :8084

Basic HTTP response check

shell
curl -I http://localhost:8084/

Find process using port 8084 (macOS/Linux)

shell
lsof -i :8084

Usage examples

Port 8084 – WEBrick / DevServer
shell
docker run -p 8084:80 myapp
curl http://localhost:8084/api/health
netstat -tlnp | grep 8084

Common services on this port

Jenkins agentIBM CICSDocker containersSpring Boot secondaryWEBrick (Ruby)

Related ports

8080

HTTP primary alternate

8085

Next sequential alternate

8083

Previous sequential alternate

History

Port 8084 has no single official service assignment. It evolved as the next sequential port after 8080-8083 in development environments running multiple services. Commonly seen in docker-compose stacks where each service gets the next available port.

FAQ

Why is something running on port 8084 that I didn't start?

Common culprits: a Docker container with port mapping, a backgrounded dev server (npm/gradle/maven), Jenkins agent, or a Kubernetes port-forward left open. Check with: lsof -i :8084 or ss -tnlp sport = :8084 to identify the process.