Network Identity
| Note: UNet is deprecated, and will be removed from Unity in the future. A new system is under development. For more information and next steps see this blog post and the FAQ. |
The Network Identity component is at the heart of the Unity networkingThe Unity system that enables multiplayer gaming across a computer network. More info
See in Glossary high-level API. It controls a GameObjectThe fundamental object in Unity scenes, which can represent characters, props, scenery, cameras, waypoints, and more. A GameObject’s functionality is defined by the Components attached to it. More info
See in Glossary’s unique identity on the network, and it uses that identity to make the networking system aware of the GameObject.
| Property | Function |
|---|---|
| Server Only | Tick this checkbox to ensure that Unity only spawns the GameObject on the server, and not on clients. |
| Local Player Authority | Tick this checkbox to give authoritative network control of this GameObject to the client that owns it. The player GameObject on that client has authority over it. Other components such as Network Transform use this to determine which client to treat as the source of authority. |
Instantiated network GameObjects
With the Unity’s server-authoritative networking system, the server must spawn networked GameObjects with network identities, using NetworkServer.Spawn. This automatically creates them on clients that are connected to the server, and assigns them a NetworkInstanceId.
You must put a Network Identity component on any PrefabsAn asset type that allows you to store a GameObject complete with components and properties. The prefab acts as a template from which you can create new object instances in the scene. More info
See in Glossary that spawn at runtime for the network system to use them. See Object Spawning for more information.
Scene-based network GameObjects
You can also network GameObjects that are saved as part of your SceneA Scene contains the environments and menus of your game. Think of each unique Scene file as a unique level. In each Scene, you place your environments, obstacles, and decorations, essentially designing and building your game in pieces. More info
See in Glossary (for example, environmental props). Networking GameObjects makes them behave slightly differently, because you need to have them spawn across the network.
When building your game, Unity disables all Scene-based GameObjects with Network Identity components. When a client connects to the server, the server sends spawn messages to tell the client which Scene GameObjects to enable and what their most up-to-date state information is. This ensures the client’s game does not contain GameObjects at incorrect locations when they start playing, or that Unity does not spawn and immediately destroy GameObjects on connection (for example, if an event removed the GameObject before that client connected). See Networked Scene GameObjects for more information.
Network Information in the preview pane
This component contains network tracking information, and displays that information in the preview pane. For example, the scene ID, network ID and asset ID the object has been assigned. This allows you to inspect the information which can be useful for investigation and debugging.
The scene ID is valid in all scene objects with a NetworkIdentity component. The network ID is the ID of this particular object instance. There might be multiple objects instantiated from a particular prefab, and the network ID is used to identity which object a network update should be applied to. The asset ID refers to which source asset the object was instantiated from. This is used internally when a particular GameObject prefab is spawned over the network.
At runtime there is more information to display here (a disabled NetworkBehaviour is displayed non-bold):
Preview Pane Information
| Property | Description |
|---|---|
| assetId | This identifies the prefab associated with this object (for spawning). |
| clientAuthorityOwner | The client that has authority for this object. This will be null if no client has authority. |
| connectionToClient | The NetworkConnection associated with this NetworkIdentity. This is only valid for player objectsA High Level API (HPAPI) object that represents the player on the server and has the ability to run commands (which are secure client-to-server remote procedure calls) from the player’s client. More info See in Glossary on the server. |
| connectionToServer | The NetworkConnection associated with this NetworkIdentity. This is only valid for player objects on a local client. |
| hasAuthority | True if this object is the authoritative version of the object. This would mean either on a the server for normal objects, or on the client with localPlayerAuthority. |
| isClient | True if this object is running on a client. |
| isLocalPlayer | This returns true if this object is the one that represents the player on the local machine. |
| isServer | True if this object is running on the server, and has been spawned. |
| localPlayerAuthority | True if this object is controlled by the client that owns it - the local player object on that client has authority over it. This is used by other components such as NetworkTransformA Networking component that allows you to synchronise the movements of GameObjects across the network. More info See in Glossary. |
| netIdA unique identifier given to an object instance to track it between networked clients and the server. More info See in Glossary |
A unique identifier for this network session, assigned when spawned. |
| observers | The list of client NetworkConnections that are able to see this object. This is read-only. |
| playerControllerId | The identifier of the controller associated with this object. Only valid for player objects. |
| SceneId | A unique identifier for networked objects in a Scene. This is only populated in play-mode. |
| serverOnly | A flag to make this object not be spawned on clients. |