Invalid Packet size on Fabric Server

[burdoto]

i've seen theres a couple of "invalid packet size" kind of issues;
but none quite matches my issue behaviour;

i literally ALWAYS get the invalid packet size error, no matter the input

server is hosted on the same machine, password is good and rcon port is unique as well. theres only one server responding to this, but it just wont get better at all no matter what i set up

rcon ports are unique, no duplicates
please let me know what further info you need.

i am running archlinux
java version is 17
mcrcon is on 0.7.2-1

[burdoto]

i just noticed when testing on another server that this does NOT apply for all servers; 1.20.1 fabric is the one that was affected

[WilsontheWolf]

I'm also having this on my fabric server. However, it doesn't seem to be every message. Specifically, help seems to error with a packet size of 4106. Then the next command I run, always errors with some large number. However, if I don't run help first, it doesn't error on the other command, and executations after the first large error work as normal.

[Taurous]

Just installed mcrcon on my server and I get this error when running help. I'm guessing the help command on a heavily modded server just has too much to send over rcon? Not sure if it's a Minecraft server limitation or this software.

[Tiiffi]

Hi,

I'm guessing the help command on a heavily modded server just has too much to send over rcon?

This is propably the reason. Vanilla minecraft doesn't send multipacket responses (it uses pages) and mcrcon doesn't support multipacket responses.

There might a problem with auth exchange too (valve style vs. vanilla minecraft style).

Not sure if it's a Minecraft server limitation or this software.

Limitation of mcrcon.

It would be really helpful if anyone could provide pcap packet capture when this problem happens (use bogus password when capturing).

Otherwise I have to install Fabric server to do some testing.

[Tiiffi]

I am unable to reproduce this problem with Vanilla or Fabric servers.

I need to know exact mods & extensions people are running on their servers.

Probable cause of failure is either too large packets or multipacket responses and I have never tested Minecraft server with multipacket responses. Most servers I have tested are splitting larger packets to pages (like Bukkit).

[burdoto]

Previously, I was encountering this issue in the All the Fabric 5 modpack; it has been updated a lot since and I am currently unable to try again, but I assume it should still be reproducible using that.