Make resilient to DDOS attack

[connorcarpenter]

Could someone, given a public IP address of a NaiaServer, and clever usage of this open-source code (a modified or unmodified NaiaClient) DDOS our server? How can we protect against this?

I'm definitely looking for advice / input here, so if you've got any, please tell me.

Possibly Useful Additions:

1. On a per-IP-address basis, allow some "suspicion" value to be accumulated for suspicious behavior. "suspicion" degrades slowly over time, but after some max level, terminates the connection. Every time the IP-address attempts to re-establish the connection thereafter, "suspicion" is raised.

If the IP-address "suspicion" levels are sufficiently high, blacklist the IP. The IP may only be allowed to re-connect once "suspicion" levels have degraded to some necessary minimum (unless placed on the blacklist). We may require some ability to clear a Server's blacklist manually ?

2. https://github.com/naia-rs/naia/blob/984673ebe65b0f38e76973f56081d8b9e53bc7c0/server/src/naia_server.rs#L236 at this point is useful, to refresh the connection with the client, but we should be checking whether there has been an established connection AFTER reading the packet_type from the StandardHeader.

This would allow us to detect when a client is sending packets of a type that typically precedes Connection establishment. Some of this is expected, but too many packets, especially after a long duration, should raise "suspicion" levels.

3. At this point: https://github.com/naia-rs/naia/blob/984673ebe65b0f38e76973f56081d8b9e53bc7c0/server/src/naia_server.rs#L288 we are receiving ClientConnectRequest packets AFTER the Connection has been established ... this should raise "suspicion" levels.

4. Non-matching Challenge Timestamps should raise "suspicion" levels. https://github.com/naia-rs/naia/blob/984673ebe65b0f38e76973f56081d8b9e53bc7c0/server/src/naia_server.rs#L303

5. Invalid ServerDigest should raise "suspicion" levels: https://github.com/naia-rs/naia/blob/984673ebe65b0f38e76973f56081d8b9e53bc7c0/server/src/naia_server.rs#L326

6. Unsuccessful Auth attempts should raise "suspicion" levels: https://github.com/naia-rs/naia/blob/984673ebe65b0f38e76973f56081d8b9e53bc7c0/server/src/naia_server.rs#L341

7. Pings, Data, and Heartbeat packets from un-authed clients should raise "suspicion" levels: https://github.com/naia-rs/naia/blob/984673ebe65b0f38e76973f56081d8b9e53bc7c0/server/src/naia_server.rs#L386, https://github.com/naia-rs/naia/blob/984673ebe65b0f38e76973f56081d8b9e53bc7c0/server/src/naia_server.rs#L406, https://github.com/naia-rs/naia/blob/984673ebe65b0f38e76973f56081d8b9e53bc7c0/server/src/naia_server.rs#L441

8. Invalid PacketType from StandardHeader should raise "suspicion" levels: https://github.com/naia-rs/naia/blob/984673ebe65b0f38e76973f56081d8b9e53bc7c0/server/src/naia_server.rs#L449

9. Errors should raise "suspicion" levels: https://github.com/naia-rs/naia/blob/984673ebe65b0f38e76973f56081d8b9e53bc7c0/server/src/naia_server.rs#L453

[Veritius]

Ideally, the termination threshold for suspicion would be optional and set on a per-app basis in config.