# MAVLink

Mavlink Communication with the Autopilot and other systems that use the MAVLink protocolMAVLink can be used to interface with components that use the MAVLink protocol and are connected to Skynode. These can be [applications running on AuterionOS](https://docs.auterion.com/developers/getting-started/application-development), payloads or other devices connected to the Skynode or its flight controller.If you wish to write a custom application which can send and receive [MAVLink ](https://mavlink.io/en/)to or from the FMU, we recommend using [MAVSDK](https://mavsdk.mavlink.io/develop/en/index.html) and connect to the interface outlined below. Some great examples can be found in the [open-source MAVSDK repository](https://github.com/mavlink/MAVSDK) and you can read our [Application Development Guide](https://docs.auterion.com/developers/getting-started/application-development-guide) to start developing your own applications for AuterionOS.MAVLink messages can be received by all MAVLink endpoints in the system, including the autopilot, camera, gimbal and Ground Control Station. Be cautious when interfacing with the system on this level to avoid any undesired behavior.

#### Internal Mavlink Communication on Skynode (Localhost) <a href="#internal-mavlink-communication-on-skynode-localhost" id="internal-mavlink-communication-on-skynode-localhost"></a>

The following table shows the available network interface to communicate with the system via the MAVLink protocol from within AuterionOS. For example when developing a new app that will be installed on AuterionOS.

| Network Interface | Listening IP Address | Port  | Transport Protocol | Purpose           |
| ----------------- | -------------------- | ----- | ------------------ | ----------------- |
| localhost         | 127.0.0.1            | 13550 | UDP                | GCS communication |
| localhost         | 127.0.0.1            | 14561 | UDP                | App 1             |
| localhost         | 127.0.0.1            | 14562 | UDP                | App 2             |
| localhost         | 127.0.0.1            | 14563 | UDP                | App 3             |

#### External Mavlink Communication to Skynode <a href="#external-mavlink-communication-to-skynode" id="external-mavlink-communication-to-skynode"></a>

| Network Interface | Listening IP Address | Port  | Transport Protocol | Purpose           |
| ----------------- | -------------------- | ----- | ------------------ | ----------------- |
| USB-C on Skynode  | 10.41.1.1            | 14550 | UDP                | GCS Communication |


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