Lineage 2 JavaScript Client

# Protocol Overview

# Data Transfer

| Header |    Content    |
| A | B  |C|D|E|F|G|H|I|…|

All fields (header and content) are written in little-endian (a.k.a. Intel's byte order). This includes both numeric and string fields.

The only field in a packet's header is a 2-byte unsigned integer, specifying the packet's total size.

| Header |    Content    |
|  Size  |               |
| A | B  |C|D|E|F|G|H|I|…|

Thus, the largest packet size is 64K (65535 bytes), with 2 bytes reserved for size. The smallest valid packet is 2 bytes long and has no real meaning (as TCP makes keep-alive redundant).

# Content

The packet's content is what server emulators typically call 'a packet'. The content starts with a unique dynamic-size prefix identifying the type of the packet, followed by the packet's actual content.

| Header |      Content      |
|  Size  | Opcode(s) |  Data |
| A | B  |C|D|E|F|G|H|I|J|K|…|

# Opcodes

If we put protocol versions that predate Prelude BETA (336) aside, then each 'packet' (emulator-wise) starts with 1 to 3 opcodes, where the 1st opcode is a single byte, 2nd – two bytes and 3rd – four bytes.

| Header |                  Content                    |
|  Size  | Opcode1 |  Opcode2  |    Opcode3    |  Data |
| A | B  |    C    |  D  |  E  | F | G | H | I |J|K|L|…|

All transmitted data is enciphered. There are different protocol encryption schemes for login and for game server communications.

← Login (Auth) Protocol →