Distributed Testing Port & Firewall Planner

Controller (Master) IPReachable VPC/LAN IP of controllerWorker (Injector) IPs10.0.1.10, 10.0.1.11, 10.0.1.12Comma or space-separated IP addresses of remote enginesRMI Registry Port (server_port)

port

Default 1099 for RMI registryWorker Engine Port (server.rmi.localport)

port

Pinned port for worker engine objectController Callback Port (client.rmi.localport)

port

Pinned return callback for sample metrics

Disable RMI SSL (server.rmi.ssl.disable=true, lab only)

Total Nodes-

Workers-

Pinned Ports-

Controller SetupWorker SetupFirewall RulesVerify PortsDocker Compose

Controller user.properties & Command

Copy active snippetCopy shareable linkReset

All calculations run client-side. IP addresses are not stored or sent to any server. See Remote Testing Manual and RMI Troubleshooting Guide.

How JMeter Distributed Testing Works

When you launch a distributed load test from a Controller (Master) against remote Workers (Injectors), JMeter uses Java RMI (Remote Method Invocation) for two-way coordination:

1. RMI Registry (server_port, default 1099): The controller connects to port 1099 on each worker node to look up the remote engine service.
2. Worker Engine Execution (server.rmi.localport, e.g. 50000): The controller sends the compiled test plan, parameters, and startup signals to the worker’s dedicated engine port.
3. Return Sample Callback (client.rmi.localport, e.g. 60000): As workers generate load, they stream sample results and metrics back to the controller over this return port.

Why Default Setups Fail in the Cloud

By default, Java RMI uses dynamic ephemeral ports (0) for engine communication and callback channels. In cloud environments (AWS Security Groups, Azure NSGs, GCP Firewalls, Docker, or Kubernetes), firewalls silently drop return packets, causing tests to freeze indefinitely at initialization.

By pinning all three ports (server_port, server.rmi.localport, and client.rmi.localport), you can write strict, deterministic firewall rules without opening wide port ranges.

---

Step-by-Step Distributed Setup Guide

1. Configure Controller (Master) Node

Place these properties in bin/user.properties on your controller machine:

remote_hosts=10.0.1.10:1099,10.0.1.11:1099,10.0.1.12:1099
client.rmi.localport=60000
mode=StrippedBatch
server.rmi.ssl.disable=false
java.rmi.server.hostname=10.0.0.5

Launch the distributed run in CLI mode:

jmeter -n -t test.jmx -R 10.0.1.10,10.0.1.11,10.0.1.12 -l results.jtl -e -o ./report

2. Configure Worker (Server) Nodes

On each worker node, configure bin/user.properties:

server_port=1099
server.rmi.localport=50000
server.rmi.ssl.disable=false

Start the daemon specifying its routable network IP address:

./bin/jmeter-server -Djava.rmi.server.hostname=10.0.1.10

3. Verify Network Reachability Before Running Tests

Always test bidirectional TCP connectivity with nc (Netcat) or Test-NetConnection (PowerShell) before starting tests:

# Test from Controller to Worker
nc -zv 10.0.1.10 1099
nc -zv 10.0.1.10 50000

# Test from Worker to Controller
nc -zv 10.0.0.5 60000

---

Related Guides & Playbooks

• Remote Testing User Manual
• Step-by-Step Distributed Testing Tutorial
• RMI Connection Refused & Port Troubleshooting
• Docker & Kubernetes Deployment Guide
• Heap Estimator for Injector Engines