UDP out node set msg.localport

General
,
1

I am running node red on an ubuntu server and I have configured one of the network adapters to have several IP addresses, like this:

network:
  ethernets:
    enp0s3:
      dhcp4: true
    enp0s8:
       dhcp4: no
       addresses:
         - 192.168.25.9/24
         - 192.168.25.23/24
         - 192.168.25.43/24
         - 192.168.25.45/24
         - 192.168.25.67/24
  version: 2

The idea is that I want to use node red to simulate several controllers, the different IP addresses corresponds to the controllers IP addresses.

In node red I am using an UDP out node to send packets and respond to heartbeat communication but I have not figured out a way to specifically send packets from for example IP 192.168.25.43. I have read something about using the bind call to specify source address but I have not managed to figure out how it works.

I found this post but I don't understand and if I try to code I get this error: TypeError: Cannot read properties of undefined (reading 'createSocket')

2

The post you're referring to, fails to mention the need to expose the dgram module to function nodes

You do this in settings.js of Node RED

  /** The following property can be used to set predefined values in Global Context.
     * This allows extra node modules to be made available with in Function node.
     * For example, the following:
     *    functionGlobalContext: { os:require('os') }
     * will allow the `os` module to be accessed in a Function node using:
     *    global.get("os")
     */
    functionGlobalContext: {
        // os:require('os'),
    },

So for you....

functionGlobalContext: {
   dgram:require('dgram')
},

You can then use the code snippet from that post in function nodes.
Remember to restart Node RED after modifying the settings file.

1 Like
3

Much easier to add dgram to the function node setup tab these days.

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