# ColumnLynx ColumnLynx is a VPN protocol designed to be as lightweight as possible. ## How does it work ColumnLynx makes use of both **TCP** and **UDP**. **TCP** is used for the initial handshake and commands, which **UDP** is used for actual packet transmission. It operates on port **48042** for both TCP and UDP. ## Packet Structure ### TCP Packets TCP Packets generally follow the structure **Packet ID + Data** #### Packet ID The **Packet ID** is an **8 bit unsigned integer** that is predefined from either the **Client to Server** or **Server to Client** enum set, however they are uniquely numbered as to not collide with each other. **Server to Client** IDs are always below **0xA0** (exclusive) and **Client to Server** IDs are always above **0xA0** (exclusive). **0xFE** and **OxFF** are shared for **GRACEFUL_DISCONNECT** and **KILL_CONNECTION** respectively. #### Data The data section is unspecified. It may change depending on the **Packet ID**. It is encoded as a **raw byte array** ### UDP Packets *WIP, fill in later* ## Legal Copyright (C) 2025 Jonas Korene Novak This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see . DcruBro is the online pseudonym of Jonas Korene Novak. Both refer to the same individual and may be used interchangeably for copyright attribution purposes. ### Licensing This project includes the [ASIO C++ Library](https://think-async.com/Asio/), distributed under the [Boost Software License, Version 1.0](https://www.boost.org/LICENSE_1_0.txt).