This application was developed to solve a problem where multiple machines need to get the same UDP packets. It functions by listening for packets on a host machine using a raw socket to not disturb the packet's intended destination from receiving it. It then sends the payload of that packet out to a target endpoint using UDP Unicast, Multicast, or Broadcast. It was built as a Windows Service backend that interacts with a GUI frontend for user interaction and system monitoring. Included in this repo is the installer for the application.

System Task-Flow

This Windows Service/Backend works by opening a raw socket with an endpoint that is specified by the user in the configuration JSON file under "Receive From". The socket used is raw so that it won't prevent the intended recipient of the packet from receiving it. Two things happen whenever a new packet is received: A copy of the packet's payload is sent out to the target "Send To" endpoint, and information about the packet is sent to the GUI/Frontend. At the same time, a task is listening continually for communication from the GUI/Frontend. This communication is made by sending packets over the loopback NIC. The Backend/Service receiving a packet from the Frontend/GUI means the user has input new configuration settings. The service then updates the configuration JSON file and restarts the thread that is listening for packets. The service is configured to begin running on system bootup under the "Local Machine" user account. This service reports its' memory used, total packets handled, and packet handling time to a user configured Prometheus endpoint. The service side has local logs in the Windows Event Log under the name:
"UDP Packet Repeater" and the source: "UDP_Repeater_Backend". Logs are also sent to a user configured Loki endpoint with the source: "Backend/Service".

The GUI/Frontend is a Windows Forms application that displays statistical data about the service running, aggregates and displays the system's logs, and provides a way for the user to update the system's settings. The main form of the frontend is the form that displays statistical data, and holds the buttons that navigate to the other children forms of the GUI. Among those children are forms for settings reconfiguration and system log display. The GUI runs as a startup application when the user logs in. It is intended to run in the background and, as such, only runs out of the system tray. This GUI reports its' memory used to a user configured Prometheus endpoint. The GUI has local logs in the Windows Event Log under: "UDP Packet Repeater" and source: "UDP_Repeater_Frontend". Logs are also sent to a user-configured Loki endpoint with the source: "Frontend/GUI".

The installer for this application is a 2 part Wix-toolset bootstrapper. It first installs .NET Framework 4.7.2 and then runs the main installer for the actual UDP Repeater Service. This installer downloads all the needed files for operation, registers the Service/Backend with the Windows Service Controller, and sets up the GUI to run on startup. Running Packet_Repeater_Installer.exe will do everything needed to get this system up and running. The source code for the installers (Bundle.wxs and Product.wxs) have paths to files that are relative to my development machine, so they will need to be updated with your correct local paths, or figure out how to use project the references to do it so that it will always work. I made it work with the service's project but didn't want to figure it out for the GUI so I just didn't.

This system implements a Prometheus/Loki/Grafana monitoring stack for simple and powerful observability. System endpoints for Prometheus metrics and Loki logging are user-configurable through the GUI. This data is visualized using a Grafana dashboard. Dashboard setup information is included in this repo in Dashboard_Config.json.

To run the Prometheus server locally, use prometheus.yml as the configuration file with the following command and parameters:

PS C:\Users> .\prometheus.exe --enable-feature=otlp-write-receiver

To run the Loki server locally, use loki-local-config.yaml as the configuration file with the following command:

PS C:\Users> .\loki-windows-amd64.exe --config.file=loki-local-config.yaml

Running Grafana Dashboard