Doesn't work with forge

[bluelightning32]

I was hoping to use your proxy to debug a problem with SpongeForge. However, I get this message when I try to login from the client:

Can't connect to server node1: This servber has mods that require FML/Forge to be installed on the client. Contact your server admin for more details

I was running it like this:

[kyle@ryoko rex]$ PYTHONPATH=$PWD/../quarry/build/lib/ python3 rex.py -c 192.168.15.2:25567 --auth <redacted>
PacketSnifferBridge{127.0.0.1} | INFO | <-- disconnect