Looking for ways to debug traffic

[Xaser]

Hi,

I have issues on my modded server with high traffic to but primarily from players. It's sometimes greater than 1 Mbit/s and appears to be related to items in water. To debug which mod / forge code is responsible, I would like to inspect the packets, but all the proxy-based sniffers (e.g. pakkit) seem to only work with vanilla minecraft. Is there some equivalent solution for forge servers that I've not been able to find? If not, what other ways to I have to inspect the packets. Since the client only shows 1-5 pkt/s TX, they must be rather big and the main contributor of packet size should be easily identifiable.

I've attached a debug.log to comply with the rules, but I don't think it will be very helpful.debug.log

[Xaser]

Hi @diesieben07,

ok I just set up a fresh modding workspace for 1.16.4 (forge-36.1.13) and I'm slowly figuring out how to attach the "projects debugger" to the server process. I'm unsure however where I should intercept with the debugger. I browsed the code and googled for info on the packet handling pipeline, but I'm still a bit unsure at which point I can really see the contents of the packet as deserialized data objects. Perhaps you have a pointer on which function to start from?

Thanks!

[Xaser]

Ok, I think I got the basics of Minecraft's packet handling and forge's SimpleImpl extension down. I also understand that this will be hell to debug, as there don't appear to be any hooks I can use to link into the processing of other mods' packets. Even adding some statistical output to the forge SimpleImpl code seems difficult as it appears that it's not intended to modify the forge code itself.

So if I got this right, my only way to go is to randomly intercept one packet at a time (which will inevitably crash the server due to timeouts and disconnect the players) and hope to get some idea of the kinds of packets arriving. Sounds fun.

Edited May 6, 2021 by Xaser