Help Packet Header

[CommanderJohnShepard]

Hello,

I am making anti-bot tool and I want to add two custom bytes after header (packet size).

 

My packets sended to server will look like

[xx xx] [m][m][nn nn nn nn nn nn nn....

 

xx - packet size (header)

m - my custom header bytes.

nn - encrypted packet

 

What's the best place to read my custom header bytes, before processing and decrypting packet on server?

 

I tried to get them inside L2GamePacketHandler.java with buf.get() before getting opcode of encrypted packet, but when server send to client a keyPacket, client sends back an unknown packet, because something bad is happening.

 

My code on server:

   public ReceivablePacket<L2GameClient> handlePacket(ByteBuffer buf, L2GameClient client)

    {

        if (client.dropPacket())

            return null;

 

        int opcode = buf.get() & 0xFF;

 

        if (opcode == 0xFE)

        {

            int _byte2 = buf.get(); // get another custom header byte

            System.out.println("Found: " +  _byte2);

 

            opcode = buf.get() & 0xFF; // now read packet opcode.

        }

 

        ReceivablePacket<L2GameClient> msg = null;

        GameClientState state = client.getState();

        

        switch (state)

        {

            case CONNECTED:

                switch (opcode)

                {

                    case 0x00:

                        msg = new ProtocolVersion();

                        break;

                    case 0x08:

 

P.S my two custom bytes are included in packet size.

Edited October 27, 2013 by CommanderJohnShepard

[xdem]

MMOCore is the place you are looking for, however you have to make the proper injections in your system's dll to make it work, cause the client will get diifferent packets that it expects

[CommanderJohnShepard]

I don't inject anything inside client. My client connects to my anti bot client, then anti-bot client resend packets to server and vice versa.

Edited October 27, 2013 by CommanderJohnShepard

[xdem]

Dude, if you have no client modification then it can be bypassed easily

[CommanderJohnShepard]

Anything can be bypassed.