Luigi Auriemma

I have a question about filtering packets so

First I'm talking about any application like IRC/chat rooms/games/Voips/other stuff

if you know what lets say a "kick packet" looks like is it possible to filter it so it would never reach your client? Thus enabling you to become immune to such things? But I see this might cause a problem with the server it might think you have been kicked but in reality you are still there? so you cant type to other client/shoot people/talk?


Lets pick css for example.

You know what the packet for when you get hit looks like
so you filter it
now when you get hit you wont lose health?

It is just a example steam probably has something to stop that(if it is possible)
I think it would work in online flash chats(without any encryption), that's why I am asking. It might turn you into a zombie connection so your username just sits there for a few minutes then the server find out something when wrong then kicks out your zombie connection.

Definitely possible to filter packets (maybe using something like Luigi's proxocket tool to ignore/alter them), but I don't know if it would do any good if the software is programmed well.

As for your kick example, smart server software should also drop everything related to a connection such as tokens, connections, etc. after it kicks a client. Those are probably incorrect terms as I don't know much about client/server terms.. but in general it would make sense. So if the server kicks the client, it will probably also close all TCP sessions (assuming the connection is TCP), or ignore future UDP traffic (assuming UDP) from that particular client unless it's traffic that's starting a new connection sequence. If it's TCP traffic, and the session is closed, the client will lose connection no matter what... and he will have to reconnect (in which case he may just be kicked again by the admin, or might be banned by IP or something else by then). If it's UDP, the server could just ignore any future packets unless they are packets related to a newly connecting client.

As for your CSS example, I would assume the the server makes the determination of whether or not you actually get hit with a bullet. So if the server goes "you got shot" and your client goes "no I didn't I never got that packet" it will probably just laugh at you (if computers could laugh :P). But in all seriousness, the server will probably end up kicking a client if they are not in agreements with each others data.

in any server application the kick operation is immediately followed by the freeing of all the resources assigned to the player (slot and related memory) and the closing of the socket so avoiding the receiving of the packet on the client doesn't avoid the kick.

P.S.: the flash chats are something a bit different and depends by the protocol used by the chat, but the thing of the freed resources should generally valid also for this type of software

Ah ok

I was just curious why no one would have done this before.

But I guess my idea was stupid.

extra but - If the server was coded so it did not close the connection(a very poorly coded server) then the idea above would work right, I'm talking about the crappiest of all servers that anyone could whip up in 5minutes only adding a kick function that just boots the player without closing the connection.

if the server was coded only to send the kick packet and without touching the player's resources (and the socket for the tcp based servers), then yes it's possible