ERROR: Guest: Tried to echo a ForwardToOthersSaved packet (3 vs 1)

[Hinne123]

Hey,

at the moment we are working on an competitive LAN multiplayer in Unity. We are using the standard TNet-Server from the asset. The last two weeks we didn't experienced any errors but since yesterday we often got clients kicked from the server with the message: "ERROR: Guest: Tried to echo a ForwardToOthersSaved packet (3 vs 1)".

What could cause this problem? Why should the guest forward any message? I thought that the client just sends his own messages and receive others?

For testings we often uses the same computer for the server and two other clients, could this cause the problem?

Best regards
Hinrich

[cmifwdll]

I think its primary purpose is anticheat. You're right that clients should send their own messages and receive others. Someone is acting maliciously and crafting, for example, a damage packet for player #1 so player #1 takes damage. The server detects this and spits out that error before kicking the malicious player.

I don't know how this could occur naturally. Do you build the forward packet manually in any of your code? If you're just using tno.Send then the packet should always be constructed properly.

[ArenMook]

There is no natural way for this error to appear without some sort of cheating intervention. At the beginning of Windward's release I had a particular hacker that was echoing packets back to the server -- usually global chat broadcasts and such. I didn't have this check in place, so the server would just forward the packets as usual, so the end result would be everyone seeing some player spam chat, when in fact it was the hacker doing it. I added this check to explicitly check for this problem.

[Hinne123]

Thanks for your answers!
We just use tno.send and tno.sendquickly. Since this is a LAN game, not published and still in development I don't think that there is someone trying to cheat 
At the moment the error didn't occur anymore. We really don't know why... at some points we took a "new" Server exe from the package, maybe this fixed the error.