i just installed some mods but when i now try to login i get the error [C->S] Unknown PacketID: 0xfa
mods that i have installed: modloader, Not enough items,Macro's keybinding,Chickenbonecore(needed for not enough items.
i think not enough items is the mod that does something.
0xfa is a packet that mods use to communicate mod data between a client and a server. Since MCServer doesn't support any kind of mods yet, there's no point in supporting that packet. We just don't support modded clients.
is there a way to let the server ignore it?

It could be implemented, but then, what is the point of having a client modded to talk to the server, if the server doesn't understand anyway?
not enough items is almost the same as toomanyitems but not enough items is a bit more advanced so not enough items just uses the commands just like toomanyitem.
I don't want to make a dummy implementation. The best course of action is to let MCS plugins handle such messages and potentially communicate with the client's mods. But for that a Lua hook needs to be made, and I don't know how to make those. It's in the hands of FakeTruth. Bug him long enough and he'll do it, he's probably bored out of his mind doing school stuff anyway
