Authentication

NexNet supports token-based authentication at the connection level. When enabled, clients must provide an authentication token during connection, and the server validates it before allowing the session to proceed.

Enabling Authentication

Authentication is disabled by default for backward compatibility. Enable it on the server config:

var serverConfig = new TcpServerConfig
{
    EndPoint = new IPEndPoint(IPAddress.Any, 5000),
    Authenticate = true
};

Server-Side Validation

Override OnAuthenticate in your server nexus to validate client tokens. Return an IIdentity on success, or null to reject the connection:

[Nexus<IServerNexus, IClientNexus>(NexusType = NexusType.Server)]
public partial class ServerNexus
{
    protected override ValueTask<IIdentity?> OnAuthenticate(ReadOnlyMemory<byte> authToken)
    {
        if (ValidateToken(authToken))
            return new ValueTask<IIdentity?>(new UserIdentity("username"));

        return new ValueTask<IIdentity?>((IIdentity?)null);
    }
}

The IIdentity returned by OnAuthenticate is available throughout the session via Context.Identity, which is used by the Authorization system for method-level access control.

Client-Side Token

Provide the authentication token on the client config via the Authenticate delegate:

var clientConfig = new TcpClientConfig
{
    EndPoint = new IPEndPoint(IPAddress.Loopback, 5000),
    Authenticate = () => Encoding.UTF8.GetBytes("my-auth-token")
};

The delegate is called each time the client connects (including reconnections), allowing you to refresh tokens as needed.

Connection Flow

sequenceDiagram
    participant Client
    participant Server
    Client->>Server: Connect with auth token
    Server->>Server: OnAuthenticate(token)
    alt Token valid
        Server-->>Client: Connection accepted
        Note over Client,Server: Session active with IIdentity
    else Token invalid
        Server-->>Client: Connection rejected
    end

See Also

• Authorization — Method-level access control using the authenticated identity
• ASP.NET Integration — Authentication via ASP.NET middleware and bearer tokens