Selenium Grid Node configuration resides on the Node itself and holds the information about network configuration and Node capabilities. The configuration can be applied in various ways:

• Default Configuration
• JSON Configuration
• Command line Configuration

JSON Configuration

The node configuration in JSON file is split into 2 sections:

• Capabilities
• Configuration

Capabilities defines areas like what Browser types and versions are supported, locations of browser binaries, number of maximum instances of each browser type.

Configuration deals with settings like hub and node addresses and ports.

Below is a an example of a JSON configuration file:

{
  "capabilities": [
    {
      "browserName": "firefox",
      "acceptSslCerts": true,
      "javascriptEnabled": true,
      "takesScreenshot": false,
      "firefox_profile": "",
      "browser-version": "27",
      "platform": "WINDOWS",
      "maxInstances": 5,
      "firefox_binary": "",
      "cleanSession": true 
    },
    {
      "browserName": "chrome",
      "maxInstances": 5,
      "platform": "WINDOWS",
      "webdriver.chrome.driver": "C:/Program Files (x86)/Google/Chrome/Application/chrome.exe"
    },
    {
      "browserName": "internet explorer",
      "maxInstances": 1,
      "platform": "WINDOWS",
      "webdriver.ie.driver": "C:/Program Files (x86)/Internet Explorer/iexplore.exe" 
    }
  ],
  "configuration": {
    "_comment" : "Configuration for Node",
    "cleanUpCycle": 2000,
    "timeout": 30000,
    "proxy": "org.openqa.grid.selenium.proxy.WebDriverRemoteProxy",
    "port": 5555,
    "host": ip,
    "register": true,
    "hubPort": 4444,
    "maxSessions": 5
  }
}

To create a node, you first need to have a hub. If you don't have a hub, you can create it like this:

java -jar selenium-server-standalone-<version>.jar -role hub

Then you're able to create a node:

java -jar selenium-server-standalone-<version>.jar -role node -hub http://localhost:4444/grid/register // default port is 4444

More info here: https://github.com/SeleniumHQ/selenium/wiki/Grid2