netcode is a secure connection-based client/server protocol built on top of UDP.

It has the following features:

• Secure client connection with connect tokens
• Client slot system where each client is assigned a client index on connect
• Encrypted and signed packets

and protects your game server from:

• Zombie clients
• Packet sniffing
• Man in the middle
• DDoS amplification
• Packet replay attacks

netcode is stable and production ready.

Start by generating a random 32 byte private key. Do not share your private key with anybody.

Especially, do not include your private key in your client executable!

Here is a test private key:

static uint8_t private_key[NETCODE_KEY_BYTES] = { 0x60, 0x6a, 0xbe, 0x6e, 0xc9, 0x19, 0x10, 0xea, 
                                                  0x9a, 0x65, 0x62, 0xf6, 0x6f, 0x2b, 0x30, 0xe4, 
                                                  0x43, 0x71, 0xd6, 0x2c, 0xd1, 0x99, 0x27, 0x26,
                                                  0x6b, 0x3c, 0x60, 0xf4, 0xb7, 0x15, 0xab, 0xa1 };

Create a server with the private key:

char * server_address = "127.0.0.1:40000";

struct netcode_server_config_t server_config;
netcode_default_server_config( &server_config );
memcpy( &server_config.private_key, private_key, NETCODE_KEY_BYTES );

struct netcode_server_t * server = netcode_server_create( server_address, &server_config, time );
if ( !server )
{
    printf( "error: failed to create server\n" );
    return 1;
}

Then start the server with the number of client slots you want:

netcode_server_start( server, 16 );

To connect a client, your client should hit a REST API to your backend that returns a connect token.

Using a connect token secures your server so that only clients authorized with your backend can connect.

netcode_client_connect( client, connect_token );

Once the client connects to the server, the client is assigned a client index and can exchange encrypted and signed packets with the server.

For more details please see client.c and server.c

This repository holds the implementation of netcode in C.

Other netcode implementations include:

• netcode C# implementation
• netcode Golang implementation
• netcode Rust implementation (updated fork of vvanders/netcode.io)
• netcode Rust implemetation (new from scratch Rust implementation)
• netcode for Unity
• netcode for UE4
• netcode for Typescript

If you'd like to create your own implementation of netcode, please read the netcode 1.02 standard.

These people are awesome:

• Val Vanders - Rust Implementation
• Walter Pearce - Rust Implementation
• Isaac Dawson - Golang Implementation
• Alan Stagner - Unity integration, C# implementation
• Jérôme Leclercq - Support for random connect token nonce
• Randy Gaul - Discovered vulnerability in replay protection
• Benny Chen - Typescript Implementation
• Benny Nazimov - Rust implementation

Thanks for your contributions to netcode!

The author of this library is Glenn Fiedler.

Other open source libraries by the same author include: reliable, serialize, and yojimbo.

If you find this software useful, please consider sponsoring it. Thanks!

BSD 3-Clause license.