Merge branch 'beta'

This version introduces protocol version 2:
 - UDP Headers stripped to 16 Bytes, allowing more throughput
 - Nonce is derived, but unique every packet - allows faster sending

ATTRIBUTIONS.md

@@ -3,7 +3,7 @@
 ## ASIO C++ Library
 - **Name:** ASIO (standalone)
 - **Website:** https://think-async.com/Asio/
-- **Copyright:** (c) 2003-2025 Christopher M. Kohlhoff
+- **Copyright:** (c) 2003-2026 Christopher M. Kohlhoff
 - **License:** Boost Software License, Version 1.0
 - **License Text:** See `third_party/asio/LICENSE_1_0.txt`
 
@@ -12,14 +12,14 @@ This project uses the standalone version of the ASIO C++ library for asynchronou
 ## CXXOPTS C++ Library
 - **Name:** cxxopts
 - **Website:** https://github.com/jarro2783/cxxopts/
-- **Copyright:** (c) 2014-2025 Christopher M. Kohlhoff
+- **Copyright:** (c) 2014-2026 Christopher M. Kohlhoff
 - **License:** MIT License
 - **License Text:** See `third_party/cxxopts/LICENSE_1_0.txt`
 
 ## Wintun C++ Library
 - **Name:** wintun
 - **Website:** https://www.wintun.net/
-- **Copyright:** (c) 2018-2025 WireGuard LLC
+- **Copyright:** (c) 2018-2026 WireGuard LLC
 - **License:** MIT License OR GPL-2.0 License
 - **License Text:** See `third_party/wintun/`
 - **Utilized Under:** MIT License

CMakeLists.txt

@@ -6,10 +6,12 @@ cmake_minimum_required(VERSION 3.16)
 # If MAJOR is 0, and MINOR > 0, Version is BETA
 
 project(ColumnLynx
-    VERSION 1.0.0
+    VERSION 1.1.0
     LANGUAGES CXX
 )
 
+include(GNUInstallDirs)
+
 # ---------------------------------------------------------
 # General C++ setup
 # ---------------------------------------------------------
@@ -40,7 +42,7 @@ endif()
 if(WIN32)
     add_compile_definitions(_WIN32_WINNT=0x0A00 NOMINMAX WIN32_LEAN_AND_MEAN)
 elseif(UNIX)
-    add_compile_options(-Wall -Wextra -Wpedantic -O3)
+    add_compile_options(-Wall -Wextra -Wpedantic -O1)
     add_link_options(-pthread)
 endif()
 
@@ -50,7 +52,7 @@ endif()
 FetchContent_Declare(
     Sodium
     GIT_REPOSITORY https://github.com/robinlinden/libsodium-cmake.git
-    GIT_TAG e5b985ad0dd235d8c4307ea3a385b45e76c74c6a  # Last updated at 2025-04-13
+    GIT_TAG e5b985ad0dd235d8c4307ea3a385b45e76c74c6a
 )
 
 set(SODIUM_DISABLE_TESTS ON CACHE BOOL "" FORCE)
@@ -157,3 +159,17 @@ target_include_directories(server PRIVATE
 )
 target_compile_definitions(server PRIVATE ASIO_STANDALONE)
 set_target_properties(server PROPERTIES OUTPUT_NAME "columnlynx_server")
+
+# ---------------------------------------------------------
+# Install rules
+# ---------------------------------------------------------
+
+install(TARGETS
+    client
+    server
+    RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
+)
+install(FILES
+	LICENSES/GPL-2.0-only.txt
+	LICENSES/GPL-3.0.txt
+        DESTINATION ${CMAKE_INSTALL_DATAROOTDIR}/licenses/${PROJECT_NAME})

README.md

@@ -57,7 +57,9 @@ openssl pkey -in key.pem -pubout -outform DER | tail -c 32 | xxd -p -c 32
 
 You can then set these keys accordingly in the **server_config** and **client_config** files.
 
-### Creating the Tun Interface (Linux Server ONLY)
+### Server Setup (Linux Server ONLY)
+
+#### Creating the Tun Interface
 
 In order for the VPN server to work, you need to create the Tun interface that the VPN will use.
 
@@ -69,6 +71,88 @@ sudo ip link set dev lynx0 mtu 1420
 sudo ip link set dev lynx0 up
 ```
 
+#### Creating the systemd service
+
+It is highly recommended to **run the server as a systemd service**, as systemd is the primary service manager on Linux.
+
+**1. Create a file for the service**
+```bash
+sudo touch /etc/systemd/system/columnlynx.service
+```
+
+**2. Open the file in your editor of choice**
+```bash
+sudo nano /etc/systemd/system/columnlynx.service
+# OR
+sudo vim /etc/systemd/system/columnlynx.service
+# OR any other editor of your choice...
+```
+
+**3. Configure the service**
+
+**Replace** the **ExecStart** and **WorkingDirectory** paths with the paths where your binaries are stored.
+
+If you configured your tun interface to belong to a custom user, you may also replace the **User** and **Group** with that user, however you must ensure that that user owns the **tun interface**, **config directory in /etc/columnlynx** and the **working directory**.
+
+This is a **simple example** for the **root user** and the executable in **/opt/columnlynx**:
+
+```
+[Unit]
+Description=ColumnLynx Server Service
+After=network.target
+
+[Service]
+Type=simple
+ExecStart=/opt/columnlynx/columnlynx_server
+WorkingDirectory=/opt/columnlynx
+User=root
+Group=root
+Restart=on-failure
+StandardOutput=append:/var/log/columnlynx.log
+StandardError=append:/var/log/columnlynx.err
+
+[Install]
+WantedBy=multi-user.target
+```
+
+**4. Reload systemd and enable the service**
+
+```bash
+sudo systemctl daemon-reload
+sudo systemctl enable columnlynx.service
+sudo systemctl start columnlynx.service
+```
+
+#### Set firewall rules
+
+This part greatly depends on your firewall of choice. Generally you just need to **allow port 48042 on both TCP and UDP** (Both IPv4 and IPv6).
+
+This example is for **UFW**:
+
+```bash
+sudo ufw allow 48042
+sudo ufw reload
+```
+
+
+#### IPTables rules for forwarding (Optional)
+
+In addition to creating the interface, you'll also need to make some **iptables** rules if you want to be able to **send traffic to foreign networks** (more like a *commercial VPN*).
+
+You can do these as such (example with NFT IPTABLES):
+
+- Enable the **generic IPv4 forwarding**:
+```bash
+sudo sysctl net.ipv4.ip_forward=1
+```
+- Create the masquerade (**Replace the IP subnet** with your own that you set in the config and **replace the interface** with your server's main (NOT *lynx0*) interface):
+```bash
+sudo nft add table nat
+sudo nft add chain nat postroute { type nat hook postrouting priority 100 \; }
+sudo nft add rule nat postroute ip saddr 10.10.0.0/24 oifname "eth0" masquerade
+```
+
+
 ### Server
  
 "**server_config**" is a file that contains the server configuration, **one variable per line**. These are the current configuration available variables:
@@ -129,6 +213,8 @@ ColumnLynx makes use of both **TCP** and **UDP**. **TCP** is used for the initia
 
 It operates on port **48042** for both TCP and UDP.
 
+Current protocol version is **2**.
+
 Generally, all transmission is done in **little-endian byte order**, since pretty much every single modern architecture uses it by default. The only exemption to this is the **transmission of IP addresses** (for the **Virtual Interface**), which is **big-endian**.
 
 ### Handshake Procedure
@@ -147,7 +233,7 @@ The Client now generates a random aesKey (32 bytes long)
 
 C: HANDSHAKE_EXCHANGE_KEY <aesKey Encrypted with Server Public Key>
 
-The Server now assigns a local 8 byte session ID in the Session Registry.
+The Server now assigns a local 4 byte session ID in the Session Registry.
 
 S: HANDSHAKE_EXCHANGE_KEY_CONFIRM <Assigned SessionID>
 ```
@@ -158,7 +244,7 @@ The **Client** and **Server** have now securely exchanged a symmetric **AES Key*
 
 Packet exchange and the general data tunneling is done via **Standard UDP** (*see the **UDP Packet** in **Data***).
 
-The **header** of the sent packet always includes a **random 12 byte nonce** used to obscure the **encrypted payload / data** and the **Session ID** assigned by the server to the client (8 bytes). This makes the header **20 bytes long**.
+The **header** of the sent packet always includes a **12 byte nonce** derived from a random **4 byte base nonce** and the **send count** to ensure a unique nonce, used to obscure the **encrypted payload / data** and the **Session ID** assigned by the server to the client (4 bytes). This makes the header **16 bytes long**.
 
 The **payload / data** of the sent packet is **always encrypted** using the exchanged **AES Key** and obscured using the **random nonce**.
 
@@ -214,7 +300,7 @@ The **Data** is generally just the **raw underlying packet** forwarded to the se
 | Type | Length | Name | Description |
 |:-----|:-------|:-----|:------------|
 | uint8_t | 12 bytes | **Header** - Nonce | Random nonce to obfuscate encrypted contents |
-| uint64_t | 8 bytes | **Header** - Session ID | The unique and random session identifier for the client |
+| uint32_t | 4 bytes | **Header** - Session ID | The unique and random session identifier for the client |
 | uint8_t | variable | Data | General data / payload |
 
 ## Misc.

include/columnlynx/client/client_session.hpp

@@ -0,0 +1,102 @@
+// client_session.hpp - Client Session data for ColumnLynx
+// Copyright (C) 2026 DcruBro
+// Distributed under the terms of the GNU General Public License, either version 2 only or version 3. See LICENSES/ for details.
+
+#pragma once
+
+#include <memory>
+#include <columnlynx/common/libsodium_wrapper.hpp>
+#include <array>
+#include <columnlynx/common/net/virtual_interface.hpp>
+#include <shared_mutex>
+
+namespace ColumnLynx {
+    struct ClientState {
+        std::shared_ptr<Utils::LibSodiumWrapper> sodiumWrapper;
+        SymmetricKey aesKey;
+        bool insecureMode;
+        std::string configPath;
+        std::shared_ptr<Net::VirtualInterface> virtualInterface;
+        uint32_t sessionID;
+        uint64_t recv_cnt;
+        uint64_t send_cnt;
+        uint32_t noncePrefix;
+
+        ~ClientState() { sodium_memzero(aesKey.data(), aesKey.size()); }
+        ClientState(const ClientState&) = delete;
+        ClientState& operator=(const ClientState&) = delete;
+        ClientState(ClientState&&) = default;
+        ClientState& operator=(ClientState&&) = default;
+
+        explicit ClientState() = default;
+
+        explicit ClientState(std::shared_ptr<Utils::LibSodiumWrapper> sodium, SymmetricKey& k, bool insecure,
+                     std::string& config, std::shared_ptr<Net::VirtualInterface> tun, uint32_t session, uint64_t recv, uint64_t send)
+        : sodiumWrapper(sodium), aesKey(k), insecureMode(insecure), configPath(config), virtualInterface(tun), sessionID(session), recv_cnt(recv), send_cnt(send) {}
+    };
+    
+    class ClientSession {
+        public:
+            // Return a reference to the Client Session instance
+            static ClientSession& getInstance() { static ClientSession instance; return instance; }
+
+            // Return the current client state
+            std::shared_ptr<ClientState> getClientState() const;
+
+            // Set the client state
+            void setClientState(std::shared_ptr<ClientState> state);
+
+            // Get the wrapper for libsodium
+            const std::shared_ptr<Utils::LibSodiumWrapper>& getSodiumWrapper() const;
+            // Get the AES key
+            const SymmetricKey& getAESKey() const;
+            // Get whether insecure mode is enabled
+            bool isInsecureMode() const;
+            // Get the config path
+            const std::string& getConfigPath() const;
+            // Get the virtual interface
+            const std::shared_ptr<Net::VirtualInterface>& getVirtualInterface() const;
+            // Get the session ID
+            uint32_t getSessionID() const;
+            uint64_t getRecvCount() const {
+                std::shared_lock lock(mMutex);
+                return mClientState->recv_cnt;
+            }
+
+            uint64_t getSendCount() const {
+                std::shared_lock lock(mMutex);
+                return mClientState->send_cnt;
+            }
+
+            uint32_t getNoncePrefix() const {
+                std::shared_lock lock(mMutex);
+                return mClientState->noncePrefix;
+            }
+
+            // Setters
+            void setSodiumWrapper(std::shared_ptr<Utils::LibSodiumWrapper> sodiumWrapper);
+            void setAESKey(const SymmetricKey& aesKey);
+            void setInsecureMode(bool insecureMode);
+            void setConfigPath(const std::string& configPath);
+            void setVirtualInterface(std::shared_ptr<Net::VirtualInterface> virtualInterface);
+            void setSessionID(uint32_t sessionID);
+            void incrementRecvCount() {
+                std::unique_lock lock(mMutex);
+                mClientState->recv_cnt++;
+            }
+
+            void incrementSendCount() {
+                std::unique_lock lock(mMutex);
+                mClientState->send_cnt++;
+            }
+
+            void setNoncePrefix(uint32_t prefix) {
+                std::unique_lock lock(mMutex);
+                mClientState->noncePrefix = prefix;
+            }
+
+        private:
+            mutable std::shared_mutex mMutex;
+            std::shared_ptr<struct ClientState> mClientState{nullptr};
+    };
+}

include/columnlynx/client/net/tcp/tcp_client.hpp

@@ -1,5 +1,5 @@
 // tcp_client.hpp - TCP Client for ColumnLynx
-// Copyright (C) 2025 DcruBro
+// Copyright (C) 2026 DcruBro
 // Distributed under the terms of the GNU General Public License, either version 2 only or version 3. See LICENSES/ for details.
 
 #pragma once
@@ -17,6 +17,7 @@
 #include <string>
 #include <columnlynx/common/net/protocol_structs.hpp>
 #include <columnlynx/common/net/virtual_interface.hpp>
+#include <columnlynx/client/client_session.hpp>
 
 using asio::ip::tcp;
 
@@ -25,28 +26,20 @@ namespace ColumnLynx::Net::TCP {
         public:
             TCPClient(asio::io_context& ioContext,
                       const std::string& host,
-                      const std::string& port,
-                      std::shared_ptr<Utils::LibSodiumWrapper> sodiumWrapper,
-                      std::shared_ptr<std::array<uint8_t, 32>> aesKey,
-                      std::shared_ptr<uint64_t> sessionIDRef,
-                      bool insecureMode,
-                      std::string& configPath,
-                      std::shared_ptr<VirtualInterface> tun = nullptr)
+                      const std::string& port)
                 :
                 mResolver(ioContext),
                 mSocket(ioContext),
                 mHost(host),
                 mPort(port),
-                mLibSodiumWrapper(sodiumWrapper),
-                mGlobalKeyRef(aesKey),
-                mSessionIDRef(sessionIDRef),
-                mInsecureMode(insecureMode),
                 mHeartbeatTimer(mSocket.get_executor()),
                 mLastHeartbeatReceived(std::chrono::steady_clock::now()),
-                mLastHeartbeatSent(std::chrono::steady_clock::now()),
-                mTun(tun),
-                mConfigDirPath(configPath)
+                mLastHeartbeatSent(std::chrono::steady_clock::now())
             {
+                // Get initial client config
+                std::string configPath = ClientSession::getInstance().getConfigPath();
+                std::shared_ptr<Utils::LibSodiumWrapper> mLibSodiumWrapper = ClientSession::getInstance().getSodiumWrapper();
+
                 // Preload the config map
                 mRawClientConfig = Utils::getConfigMap(configPath + "client_config");
 
@@ -104,20 +97,14 @@ namespace ColumnLynx::Net::TCP {
             std::string mHost, mPort;
             uint8_t mServerPublicKey[32]; // Assuming 256-bit public key
             std::array<uint8_t, 32> mSubmittedChallenge{};
-            std::shared_ptr<Utils::LibSodiumWrapper> mLibSodiumWrapper;
-            uint64_t mConnectionSessionID;
+            uint32_t mConnectionSessionID;
             SymmetricKey mConnectionAESKey;
-            std::shared_ptr<std::array<uint8_t, 32>> mGlobalKeyRef; // Reference to global AES key
-            std::shared_ptr<uint64_t> mSessionIDRef; // Reference to global Session ID
-            bool mInsecureMode; // Insecure mode flag
             asio::steady_timer mHeartbeatTimer;
             std::chrono::steady_clock::time_point mLastHeartbeatReceived;
             std::chrono::steady_clock::time_point mLastHeartbeatSent;
             int mMissedHeartbeats = 0;
             bool mIsHostDomain;
             Protocol::TunConfig mTunConfig;
-            std::shared_ptr<VirtualInterface> mTun = nullptr;
             std::unordered_map<std::string, std::string> mRawClientConfig;
-            std::string mConfigDirPath;
     };
 }

include/columnlynx/client/net/udp/udp_client.hpp

@@ -1,5 +1,5 @@
 // udp_client.hpp - UDP Client for ColumnLynx
-// Copyright (C) 2025 DcruBro
+// Copyright (C) 2026 DcruBro
 // Distributed under the terms of the GNU General Public License, either version 2 only or version 3. See LICENSES/ for details.
 
 #pragma once
@@ -10,17 +10,15 @@
 #include <columnlynx/common/libsodium_wrapper.hpp>
 #include <array>
 #include <columnlynx/common/net/virtual_interface.hpp>
+#include <columnlynx/client/client_session.hpp>
 
 namespace ColumnLynx::Net::UDP {
     class UDPClient {
         public:
             UDPClient(asio::io_context& ioContext,
                       const std::string& host,
-                      const std::string& port,
-                      std::shared_ptr<std::array<uint8_t, 32>> aesKeyRef,
-                      std::shared_ptr<uint64_t> sessionIDRef,
-                      std::shared_ptr<VirtualInterface> tunRef = nullptr)
-                : mSocket(ioContext), mResolver(ioContext), mHost(host), mPort(port), mAesKeyRef(aesKeyRef), mSessionIDRef(sessionIDRef), mTunRef(tunRef) 
+                      const std::string& port)
+                : mSocket(ioContext), mResolver(ioContext), mHost(host), mPort(port)
             {
                 mStartReceive(); 
             }
@@ -43,9 +41,6 @@ namespace ColumnLynx::Net::UDP {
             asio::ip::udp::endpoint mRemoteEndpoint;
             std::string mHost;
             std::string mPort;
-            std::shared_ptr<std::array<uint8_t, 32>> mAesKeyRef;
-            std::shared_ptr<uint64_t> mSessionIDRef;
-            std::shared_ptr<VirtualInterface> mTunRef = nullptr;
             std::array<uint8_t, 2048> mRecvBuffer; // Adjust size as needed
     };
 }

include/columnlynx/common/libsodium_wrapper.hpp

@@ -1,5 +1,5 @@
 // libsodium_wrapper.hpp - Libsodium Wrapper for ColumnLynx
-// Copyright (C) 2025 DcruBro
+// Copyright (C) 2026 DcruBro
 // Distributed under the terms of the GNU General Public License, either version 2 only or version 3. See LICENSES/ for details.
 
 #pragma once

include/columnlynx/common/net/protocol_structs.hpp

@@ -1,5 +1,5 @@
 // protocol_structs.hpp - Network Protocol Structures
-// Copyright (C) 2025 DcruBro
+// Copyright (C) 2026 DcruBro
 // Distributed under the terms of the GNU General Public License, either version 2 only or version 3. See LICENSES/ for details.
 
 #pragma once

include/columnlynx/common/net/session_registry.hpp

@@ -1,5 +1,5 @@
 // session_registry.hpp - Session Registry for ColumnLynx
-// Copyright (C) 2025 DcruBro
+// Copyright (C) 2026 DcruBro
 // Distributed under the terms of the GNU General Public License, either version 2 only or version 3. See LICENSES/ for details.
 
 #pragma once
@@ -27,8 +27,9 @@ namespace ColumnLynx::Net {
         std::chrono::steady_clock::time_point expires{}; // Time of expiry
         uint32_t clientTunIP; // Assigned IP
         uint32_t serverTunIP; // Server IP
-        uint64_t sessionID; // Session ID
+        uint32_t sessionID; // Session ID
         Nonce base_nonce{};
+        uint32_t noncePrefix;
 
         ~SessionState() { sodium_memzero(aesKey.data(), aesKey.size()); }
         SessionState(const SessionState&) = delete;
@@ -36,7 +37,7 @@ namespace ColumnLynx::Net {
         SessionState(SessionState&&) = default;
         SessionState& operator=(SessionState&&) = default;
 
-        explicit SessionState(const SymmetricKey& k, std::chrono::seconds ttl = std::chrono::hours(24), uint32_t clientIP = 0, uint32_t serverIP = 0, uint64_t id = 0) : aesKey(k), clientTunIP(clientIP), serverTunIP(serverIP), sessionID(id) {
+        explicit SessionState(const SymmetricKey& k, std::chrono::seconds ttl = std::chrono::hours(24), uint32_t clientIP = 0, uint32_t serverIP = 0, uint32_t id = 0) : aesKey(k), clientTunIP(clientIP), serverTunIP(serverIP), sessionID(id) {
             expires = created + ttl;
         }
 
@@ -44,6 +45,11 @@ namespace ColumnLynx::Net {
         void setUDPEndpoint(const asio::ip::udp::endpoint& ep) {
             udpEndpoint = ep;
         }
+
+        void setBaseNonce() {
+            Utils::debug("Generating random base nonce for session " + std::to_string(sessionID));
+            randombytes_buf(base_nonce.data(), base_nonce.size());
+        }
     };
 
     class SessionRegistry {
@@ -52,19 +58,19 @@ namespace ColumnLynx::Net {
             static SessionRegistry& getInstance() { static SessionRegistry instance; return instance; }
 
             // Insert or replace a session entry
-            void put(uint64_t sessionID, std::shared_ptr<SessionState> state);
+            void put(uint32_t sessionID, std::shared_ptr<SessionState> state);
 
             // Lookup a session entry by session ID
-            std::shared_ptr<const SessionState> get(uint64_t sessionID) const;
+            std::shared_ptr<const SessionState> get(uint32_t sessionID) const;
 
             // Lookup a session entry by IPv4
             std::shared_ptr<const SessionState> getByIP(uint32_t ip) const;
 
             // Get a snapshot of the Session Registry
-            std::unordered_map<uint64_t, std::shared_ptr<SessionState>> snapshot() const;
+            std::unordered_map<uint32_t, std::shared_ptr<SessionState>> snapshot() const;
 
             // Remove a session by ID
-            void erase(uint64_t sessionID);
+            void erase(uint32_t sessionID);
 
             // Cleanup expired sessions
             void cleanupExpired();
@@ -72,21 +78,23 @@ namespace ColumnLynx::Net {
             // Get the number of registered sessions
             int size() const;
 
+            bool exists(uint32_t sessionID) const;
+
             // IP management
 
             // Get the lowest available IPv4 address; Returns 0 if none available
             uint32_t getFirstAvailableIP(uint32_t baseIP, uint8_t mask) const;
 
             // Lock IP to session ID; Do NOT call before put() - You will segfault!
-            void lockIP(uint64_t sessionID, uint32_t ip);
+            void lockIP(uint32_t sessionID, uint32_t ip);
 
             // Unlock IP from session ID
-            void deallocIP(uint64_t sessionID);
+            void deallocIP(uint32_t sessionID);
 
         private:
             mutable std::shared_mutex mMutex;
-            std::unordered_map<uint64_t, std::shared_ptr<SessionState>> mSessions;
-            std::unordered_map<uint64_t, uint32_t> mSessionIPs;
+            std::unordered_map<uint32_t, std::shared_ptr<SessionState>> mSessions;
+            std::unordered_map<uint32_t, uint32_t> mSessionIPs;
             std::unordered_map<uint32_t, std::shared_ptr<SessionState>> mIPSessions;
     };
 }

include/columnlynx/common/net/tcp/net_helper.hpp

@@ -1,5 +1,5 @@
 // net_helper.hpp - Network Helper Functions for ColumnLynx
-// Copyright (C) 2025 DcruBro
+// Copyright (C) 2026 DcruBro
 // Distributed under the terms of the GNU General Public License, either version 2 only or version 3. See LICENSES/ for details.
 
 #pragma once

include/columnlynx/common/net/tcp/tcp_message_handler.hpp

@@ -1,5 +1,5 @@
 // tcp_message_handler.hpp - TCP Message Handler for ColumnLynx
-// Copyright (C) 2025 DcruBro
+// Copyright (C) 2026 DcruBro
 // Distributed under the terms of the GNU General Public License, either version 2 only or version 3. See LICENSES/ for details.
 
 #pragma once

include/columnlynx/common/net/tcp/tcp_message_type.hpp

@@ -1,5 +1,5 @@
 // tcp_message_type.hpp - TCP Message Types for ColumnLynx
-// Copyright (C) 2025 DcruBro
+// Copyright (C) 2026 DcruBro
 // Distributed under the terms of the GNU General Public License, either version 2 only or version 3. See LICENSES/ for details.
 
 #pragma once

include/columnlynx/common/net/udp/udp_message_type.hpp

@@ -1,5 +1,5 @@
 // udp_message_type.hpp - UDP Message Types for ColumnLynx
-// Copyright (C) 2025 DcruBro
+// Copyright (C) 2026 DcruBro
 // Distributed under the terms of the GNU General Public License, either version 2 only or version 3. See LICENSES/ for details.
 
 #pragma once

include/columnlynx/common/net/virtual_interface.hpp

@@ -1,5 +1,5 @@
 // virtual_interface.hpp - Virtual Interface for Network Communication
-// Copyright (C) 2025 DcruBro
+// Copyright (C) 2026 DcruBro
 // Distributed under the terms of the GNU General Public License, either version 2 only or version 3. See LICENSES/ for details.
 
 #pragma once
@@ -36,6 +36,12 @@
     #include <locale>
     #include <codecvt>
     #include <wintun/wintun.h>
+
+    #include <iphlpapi.h>
+    #include <netioapi.h>
+    
+    #pragma comment(lib, "iphlpapi.lib")
+    #pragma comment(lib, "ws2_32.lib")
 #endif
 
 namespace ColumnLynx::Net {

include/columnlynx/common/panic_handler.hpp

@@ -1,5 +1,5 @@
 // panic_handler.hpp - Panic Handler for ColumnLynx
-// Copyright (C) 2025 DcruBro
+// Copyright (C) 2026 DcruBro
 // Distributed under the terms of the GNU General Public License, either version 2 only or version 3. See LICENSES/ for details.
 
 #pragma once

include/columnlynx/common/utils.hpp

@@ -1,5 +1,5 @@
 // utils.hpp - Utility functions for ColumnLynx
-// Copyright (C) 2025 DcruBro
+// Copyright (C) 2026 DcruBro
 // Distributed under the terms of the GNU General Public License, either version 2 only or version 3. See LICENSES/ for details.
 
 #pragma once
@@ -15,6 +15,7 @@
 #include <unordered_map>
 #include <unordered_set>
 #include <algorithm>
+#include <bits/stdc++.h>
 
 #ifdef _WIN32
     #include <winsock2.h>
@@ -29,6 +30,9 @@ namespace ColumnLynx {
 }
 
 namespace ColumnLynx::Utils {
+    // Converts unix milliseconds to a local ISO 8601 formatted string; Defaults to local time; Will use UTC if local is false.
+    std::string unixMillisToISO8601(uint64_t unixMillis, bool local = true);
+
     // General log function. Use for logging important information.
     void log(const std::string &msg);
     // General warning function. Use for logging important warnings.
@@ -61,27 +65,6 @@ namespace ColumnLynx::Utils {
         return std::string(reinterpret_cast<const char*>(data), length);
     }
 
-    inline constexpr uint64_t cbswap64(uint64_t x) {
-        return ((x & 0x00000000000000FFULL) << 56) |
-               ((x & 0x000000000000FF00ULL) << 40) |
-               ((x & 0x0000000000FF0000ULL) << 24) |
-               ((x & 0x00000000FF000000ULL) << 8)  |
-               ((x & 0x000000FF00000000ULL) >> 8)  |
-               ((x & 0x0000FF0000000000ULL) >> 24) |
-               ((x & 0x00FF000000000000ULL) >> 40) |
-               ((x & 0xFF00000000000000ULL) >> 56);
-    }
-
-    // host -> big-endian (for little-endian hosts) - 64 bit
-    inline constexpr uint64_t chtobe64(uint64_t x) {
-        return cbswap64(x);
-    }
-
-    // big-endian -> host (for little-endian hosts) - 64 bit
-    inline constexpr uint64_t cbe64toh(uint64_t x) {
-        return cbswap64(x);
-    }
-
     template <typename T>
     T cbswap128(const T& x) {
         static_assert(sizeof(T) == 16, "cbswap128 requires a 128-bit type");

include/columnlynx/server/net/tcp/tcp_connection.hpp

@@ -1,5 +1,5 @@
 // tcp_connection.hpp - TCP Connection for ColumnLynx
-// Copyright (C) 2025 DcruBro
+// Copyright (C) 2026 DcruBro
 // Distributed under the terms of the GNU General Public License, either version 2 only or version 3. See LICENSES/ for details.
 
 #pragma once
@@ -18,6 +18,7 @@
 #include <columnlynx/common/net/session_registry.hpp>
 #include <columnlynx/common/net/protocol_structs.hpp>
 #include <columnlynx/common/net/virtual_interface.hpp>
+#include <columnlynx/server/server_session.hpp>
 
 namespace ColumnLynx::Net::TCP {
     class TCPConnection : public std::enable_shared_from_this<TCPConnection> {
@@ -26,12 +27,9 @@ namespace ColumnLynx::Net::TCP {
 
             static pointer create(
                 asio::ip::tcp::socket socket,
-                std::shared_ptr<Utils::LibSodiumWrapper> sodiumWrapper,
-                std::unordered_map<std::string, std::string>* serverConfig,
-                std::string configDirPath,
                 std::function<void(pointer)> onDisconnect)
             {
-                auto conn = pointer(new TCPConnection(std::move(socket), sodiumWrapper, serverConfig, configDirPath));
+                auto conn = pointer(new TCPConnection(std::move(socket)));
                 conn->mOnDisconnect = std::move(onDisconnect);
                 return conn;
             }
@@ -46,20 +44,17 @@ namespace ColumnLynx::Net::TCP {
             void disconnect(bool echo = true);
 
             // Get the assigned session ID
-            uint64_t getSessionID() const;
+            uint32_t getSessionID() const;
             // Get the assigned AES key; You should probably access this via the Session Registry instead
             std::array<uint8_t, 32> getAESKey() const;
         
         private:
-            TCPConnection(asio::ip::tcp::socket socket, std::shared_ptr<Utils::LibSodiumWrapper> sodiumWrapper, std::unordered_map<std::string, std::string>* serverConfig, std::string configDirPath)
+            TCPConnection(asio::ip::tcp::socket socket)
                 :
                 mHandler(std::make_shared<MessageHandler>(std::move(socket))),
-                mLibSodiumWrapper(sodiumWrapper),
-                mRawServerConfig(serverConfig),
                 mHeartbeatTimer(mHandler->socket().get_executor()),
                 mLastHeartbeatReceived(std::chrono::steady_clock::now()),
-                mLastHeartbeatSent(std::chrono::steady_clock::now()),
-                mConfigDirPath(configDirPath)
+                mLastHeartbeatSent(std::chrono::steady_clock::now())
             {}
 
             // Start the heartbeat routine
@@ -69,16 +64,13 @@ namespace ColumnLynx::Net::TCP {
 
             std::shared_ptr<MessageHandler> mHandler;
             std::function<void(std::shared_ptr<TCPConnection>)> mOnDisconnect;
-            std::shared_ptr<Utils::LibSodiumWrapper> mLibSodiumWrapper;
-            std::unordered_map<std::string, std::string>* mRawServerConfig;
             std::array<uint8_t, 32> mConnectionAESKey;
-            uint64_t mConnectionSessionID;
+            uint32_t mConnectionSessionID;
             AsymPublicKey mConnectionPublicKey;
             asio::steady_timer mHeartbeatTimer;
             std::chrono::steady_clock::time_point mLastHeartbeatReceived;
             std::chrono::steady_clock::time_point mLastHeartbeatSent;
             int mMissedHeartbeats = 0;
             std::string mRemoteIP; // Cached remote IP to avoid calling remote_endpoint() on closed sockets
-            std::string mConfigDirPath;
     };
 }

include/columnlynx/server/net/tcp/tcp_server.hpp

@@ -1,5 +1,5 @@
 // tcp_server.hpp - TCP Server for ColumnLynx
-// Copyright (C) 2025 DcruBro
+// Copyright (C) 2026 DcruBro
 // Distributed under the terms of the GNU General Public License, either version 2 only or version 3. See LICENSES/ for details.
 
 #pragma once
@@ -17,29 +17,23 @@
 #include <columnlynx/server/net/tcp/tcp_connection.hpp>
 #include <columnlynx/common/libsodium_wrapper.hpp>
 #include <columnlynx/common/net/protocol_structs.hpp>
+#include <columnlynx/server/server_session.hpp>
 
 namespace ColumnLynx::Net::TCP {
 
     class TCPServer {
         public:
             TCPServer(asio::io_context& ioContext,
-                      uint16_t port,
-                      std::shared_ptr<Utils::LibSodiumWrapper> sodiumWrapper,
-                      std::shared_ptr<bool> hostRunning,
-                      std::string& configPath,
-                      bool ipv4Only = false)
+                      uint16_t port)
                 : mIoContext(ioContext),
-                  mAcceptor(ioContext),
-                  mSodiumWrapper(sodiumWrapper),
-                  mHostRunning(hostRunning),
-                  mConfigDirPath(configPath)
+                  mAcceptor(ioContext)
             {
                 // Preload the config map
-                mRawServerConfig = Utils::getConfigMap(configPath + "server_config", {"NETWORK", "SUBNET_MASK"});
-
                 asio::error_code ec_open, ec_v6only, ec_bind;
 
-                if (!ipv4Only) {
+                bool isIPv4Only = ServerSession::getInstance().isIPv4Only();
+
+                if (!isIPv4Only) {
                     // Try IPv6 (dual-stack if supported)
                     asio::ip::tcp::endpoint endpoint_v6(asio::ip::tcp::v6(), port);
                 
@@ -55,8 +49,8 @@ namespace ColumnLynx::Net::TCP {
                 }
                 
                 // If IPv6 bind failed OR IPv6 open failed OR forced IPv4-only
-                if (ipv4Only || ec_open || ec_bind) {
-                    if (!ipv4Only)
+                if (isIPv4Only || ec_open || ec_bind) {
+                    if (!isIPv4Only)
                         Utils::warn("TCP: IPv6 unavailable (open=" + ec_open.message() +
                                     ", bind=" + ec_bind.message() +
                                     "), falling back to IPv4 only");
@@ -84,10 +78,6 @@ namespace ColumnLynx::Net::TCP {
             asio::io_context &mIoContext;
             asio::ip::tcp::acceptor mAcceptor;
             std::unordered_set<TCPConnection::pointer> mClients;
-            std::shared_ptr<Utils::LibSodiumWrapper> mSodiumWrapper;
-            std::shared_ptr<bool> mHostRunning;
-            std::unordered_map<std::string, std::string> mRawServerConfig;
-            std::string mConfigDirPath;
     };
 
 }

include/columnlynx/server/net/udp/udp_server.hpp

@@ -1,5 +1,5 @@
 // udp_server.hpp - UDP Server for ColumnLynx
-// Copyright (C) 2025 DcruBro
+// Copyright (C) 2026 DcruBro
 // Distributed under the terms of the GNU General Public License, either version 2 only or version 3. See LICENSES/ for details.
 
 #pragma once
@@ -9,16 +9,18 @@
 #include <columnlynx/common/utils.hpp>
 #include <array>
 #include <columnlynx/common/net/virtual_interface.hpp>
+#include <columnlynx/common/libsodium_wrapper.hpp>
+#include <columnlynx/server/server_session.hpp>
 
 namespace ColumnLynx::Net::UDP {
     class UDPServer {
         public:
-            UDPServer(asio::io_context& ioContext, uint16_t port, std::shared_ptr<bool> hostRunning, bool ipv4Only = false, std::shared_ptr<VirtualInterface> tun = nullptr)
-                : mSocket(ioContext), mHostRunning(hostRunning), mTun(tun)
+            UDPServer(asio::io_context& ioContext, uint16_t port)
+                : mSocket(ioContext)
             {
                 asio::error_code ec_open, ec_v6only, ec_bind;
 
-                if (!ipv4Only) {
+                if (!mIpv4Only) {
                     asio::ip::udp::endpoint endpoint_v6(asio::ip::udp::v6(), port);
                 
                     // Try opening IPv6 socket
@@ -34,8 +36,8 @@ namespace ColumnLynx::Net::UDP {
                 }
 
                 // Fallback to IPv4 if IPv6 is unusable
-                if (ipv4Only || ec_open || ec_bind) {
-                    if (!ipv4Only) {
+                if (mIpv4Only || ec_open || ec_bind) {
+                    if (!mIpv4Only) {
                         Utils::warn(
                             "UDP: IPv6 unavailable (open=" + ec_open.message() +
                             ", bind=" + ec_bind.message() +
@@ -59,7 +61,7 @@ namespace ColumnLynx::Net::UDP {
             void stop();
 
             // Send UDP data to an endpoint; Fetched via the Session Registry
-            void sendData(const uint64_t sessionID, const std::string& data);
+            void sendData(uint32_t sessionID, const std::string& data);
 
         private:
             // Start receiving UDP data
@@ -70,7 +72,7 @@ namespace ColumnLynx::Net::UDP {
             asio::ip::udp::socket mSocket;
             asio::ip::udp::endpoint mRemoteEndpoint;
             std::array<uint8_t, 2048> mRecvBuffer; // 2048 seems stable
-            std::shared_ptr<bool> mHostRunning;
-            std::shared_ptr<VirtualInterface> mTun;
+            bool mIpv4Only = ServerSession::getInstance().isIPv4Only();
+            const std::shared_ptr<VirtualInterface> mTun = ServerSession::getInstance().getVirtualInterface();
     };
 }

include/columnlynx/server/server_session.hpp

@@ -0,0 +1,62 @@
+// server_session.hpp - Client Session data for ColumnLynx
+// Copyright (C) 2026 DcruBro
+// Distributed under the terms of the GNU General Public License, either version 2 only or version 3. See LICENSES/ for details.
+
+#pragma once
+
+#include <memory>
+#include <columnlynx/common/libsodium_wrapper.hpp>
+#include <array>
+#include <columnlynx/common/net/virtual_interface.hpp>
+#include <shared_mutex>
+
+namespace ColumnLynx {
+    struct ServerState {
+        std::shared_ptr<Utils::LibSodiumWrapper> sodiumWrapper;
+        std::shared_ptr<Net::VirtualInterface> virtualInterface;
+        std::string configPath;
+        std::unordered_map<std::string, std::string> serverConfig;
+        bool ipv4Only;
+        bool hostRunning;
+
+        ~ServerState() = default;
+        ServerState(const ServerState&) = delete;
+        ServerState& operator=(const ServerState&) = delete;
+        ServerState(ServerState&&) = default;
+        ServerState& operator=(ServerState&&) = default;
+
+        explicit ServerState() = default;
+    };
+    
+    class ServerSession {
+        public:
+            // Return a reference to the Server Session instance
+            static ServerSession& getInstance() { static ServerSession instance; return instance; }
+
+            // Return the current server state
+            std::shared_ptr<ServerState> getServerState() const;
+
+            // Set the server state
+            void setServerState(std::shared_ptr<ServerState> state);
+
+            // Getters
+            std::shared_ptr<Utils::LibSodiumWrapper> getSodiumWrapper() const;
+            const std::string& getConfigPath() const;
+            const std::unordered_map<std::string, std::string>& getRawServerConfig() const;
+            const std::shared_ptr<Net::VirtualInterface>& getVirtualInterface() const;
+            bool isIPv4Only() const;
+            bool isHostRunning() const;
+
+            // Setters
+            void setSodiumWrapper(std::shared_ptr<Utils::LibSodiumWrapper> sodiumWrapper);
+            void setConfigPath(const std::string& configPath);
+            void setRawServerConfig(const std::unordered_map<std::string, std::string>& config);
+            void setVirtualInterface(std::shared_ptr<Net::VirtualInterface> tun);
+            void setIPv4Only(bool ipv4Only);
+            void setHostRunning(bool hostRunning);
+
+        private:
+            mutable std::shared_mutex mMutex;
+            std::shared_ptr<struct ServerState> mServerState{nullptr};
+    };
+}

src/client/client_session.cpp

@@ -0,0 +1,71 @@
+// client_session.cpp - Client Session data for ColumnLynx
+// Copyright (C) 2026 DcruBro
+// Distributed under the terms of the GNU General Public License, either version 2 only or version 3. See LICENSES/ for details.
+
+#include <columnlynx/client/client_session.hpp>
+
+namespace ColumnLynx {
+    std::shared_ptr<ClientState> ClientSession::getClientState() const {
+        std::shared_lock lock(mMutex);
+        return mClientState;
+    }
+
+    void ClientSession::setClientState(std::shared_ptr<ClientState> state) {
+        std::unique_lock lock(mMutex);
+        mClientState = state;
+    }
+
+    const std::shared_ptr<Utils::LibSodiumWrapper>& ClientSession::getSodiumWrapper() const {
+        return getClientState()->sodiumWrapper;
+    }
+
+    const SymmetricKey& ClientSession::getAESKey() const {
+        return getClientState()->aesKey;
+    }
+
+    bool ClientSession::isInsecureMode() const {
+        return getClientState()->insecureMode;
+    }
+
+    const std::string& ClientSession::getConfigPath() const {
+        return getClientState()->configPath;
+    }
+
+    const std::shared_ptr<Net::VirtualInterface>& ClientSession::getVirtualInterface() const {
+        return getClientState()->virtualInterface;
+    }
+
+    uint32_t ClientSession::getSessionID() const {
+        return getClientState()->sessionID;
+    }
+
+    void ClientSession::setSodiumWrapper(std::shared_ptr<Utils::LibSodiumWrapper> sodiumWrapper) {
+        std::unique_lock lock(mMutex);
+        mClientState->sodiumWrapper = sodiumWrapper;
+    }
+
+    void ClientSession::setAESKey(const SymmetricKey& aesKey) {
+        std::unique_lock lock(mMutex);
+        mClientState->aesKey = aesKey;
+    }
+
+    void ClientSession::setInsecureMode(bool insecureMode) {
+        std::unique_lock lock(mMutex);
+        mClientState->insecureMode = insecureMode;
+    }
+
+    void ClientSession::setConfigPath(const std::string& configPath) {
+        std::unique_lock lock(mMutex);
+        mClientState->configPath = configPath;
+    }
+
+    void ClientSession::setVirtualInterface(std::shared_ptr<Net::VirtualInterface> virtualInterface) {
+        std::unique_lock lock(mMutex);
+        mClientState->virtualInterface = virtualInterface;
+    }
+
+    void ClientSession::setSessionID(uint32_t sessionID) {
+        std::unique_lock lock(mMutex);
+        mClientState->sessionID = sessionID;
+    }
+}

src/client/main.cpp

@@ -1,5 +1,5 @@
 // main.cpp - Client entry point for ColumnLynx
-// Copyright (C) 2025 DcruBro
+// Copyright (C) 2026 DcruBro
 // Distributed under the terms of the GNU General Public License, either version 2 only or version 3. See LICENSES/ for details.
 
 #include <asio.hpp>
@@ -11,6 +11,8 @@
 #include <columnlynx/client/net/udp/udp_client.hpp>
 #include <cxxopts.hpp>
 #include <columnlynx/common/net/virtual_interface.hpp>
+#include <columnlynx/client/client_session.hpp>
+#include <thread>
 
 #if defined(__WIN32__)
 #include <windows.h>
@@ -68,7 +70,7 @@ int main(int argc, char** argv) {
     if (optionsObj.count("help")) {
         std::cout << options.help() << std::endl;
         std::cout << "This software is licensed under the GPLv2-only license OR the GPLv3 license.\n";
-        std::cout << "Copyright (C) 2025, The ColumnLynx Contributors.\n";
+        std::cout << "Copyright (C) 2026, The ColumnLynx Contributors.\n";
         std::cout << "This software is provided under ABSOLUTELY NO WARRANTY, to the extent permitted by law.\n";
         return 0;
     }
@@ -99,20 +101,37 @@ int main(int argc, char** argv) {
             #endif
         }
 
+        struct ClientState initialState{};
+        initialState.configPath = configPath;
+        initialState.insecureMode = insecureMode;
+        initialState.send_cnt = 0;
+        initialState.recv_cnt = 0;
+        randombytes_buf(&initialState.noncePrefix, sizeof(uint32_t)); // Randomize nonce prefix
+
         std::shared_ptr<VirtualInterface> tun = std::make_shared<VirtualInterface>(optionsObj["interface"].as<std::string>());
         log("Using virtual interface: " + tun->getName());
+        initialState.virtualInterface = tun;
 
         std::shared_ptr<LibSodiumWrapper> sodiumWrapper = std::make_shared<LibSodiumWrapper>();
         debug("Public Key: " + Utils::bytesToHexString(sodiumWrapper->getPublicKey(), 32));
         debug("Private Key: " + Utils::bytesToHexString(sodiumWrapper->getPrivateKey(), 64));
+        initialState.sodiumWrapper = sodiumWrapper;
 
-        std::shared_ptr<std::array<uint8_t, 32>> aesKey = std::make_shared<std::array<uint8_t, 32>>(); 
-        aesKey->fill(0); // Defualt zeroed state until modified by handshake
-        std::shared_ptr<uint64_t> sessionID = std::make_shared<uint64_t>(0);
+        std::array<uint8_t, 32> aesKey = std::array<uint8_t, 32>(); 
+        aesKey.fill(0); // Defualt zeroed state until modified by handshake
+        uint32_t sessionID = 0;
+        initialState.aesKey = aesKey;
+        initialState.sessionID = sessionID;
+
+        ColumnLynx::ClientSession::getInstance().setClientState(std::make_shared<ClientState>(std::move(initialState))); // Set initial state
+
+        if (insecureMode) {
+            warn("You have started the client with the --ignore-whitelist. This means that the client will NOT attempt to verify the server's public key. This is INSECURE and SHOULDN'T be used!");
+        }
 
         asio::io_context io;
-        auto client = std::make_shared<ColumnLynx::Net::TCP::TCPClient>(io, host, port, sodiumWrapper, aesKey, sessionID, insecureMode, configPath, tun);
-        auto udpClient = std::make_shared<ColumnLynx::Net::UDP::UDPClient>(io, host, port, aesKey, sessionID, tun);
+        auto client = std::make_shared<ColumnLynx::Net::TCP::TCPClient>(io, host, port); // TODO: Move to ClientSession state
+        auto udpClient = std::make_shared<ColumnLynx::Net::UDP::UDPClient>(io, host, port);
 
         client->start();
         udpClient->start();

src/client/net/tcp/tcp_client.cpp

@@ -1,5 +1,5 @@
 // tcp_client.cpp - TCP Client for ColumnLynx
-// Copyright (C) 2025 DcruBro
+// Copyright (C) 2026 DcruBro
 // Distributed under the terms of the GNU General Public License, either version 2 only or version 3. See LICENSES/ for details.
 
 #include <columnlynx/client/net/tcp/tcp_client.hpp>
@@ -46,10 +46,13 @@ namespace ColumnLynx::Net::TCP {
                                 std::vector<uint8_t> payload;
                                 payload.reserve(1 + crypto_box_PUBLICKEYBYTES);
                                 payload.push_back(Utils::protocolVersion());
+                                Utils::log("Using protocol version: " + std::to_string(Utils::protocolVersion()));
                                 /*payload.insert(payload.end(),
                                     mLibSodiumWrapper->getXPublicKey(),
                                     mLibSodiumWrapper->getXPublicKey() + crypto_box_PUBLICKEYBYTES
                                 );*/
+
+                                const auto& mLibSodiumWrapper = ClientSession::getInstance().getSodiumWrapper();
                                 payload.insert(payload.end(),
                                     mLibSodiumWrapper->getPublicKey(),
                                     mLibSodiumWrapper->getPublicKey() + crypto_sign_PUBLICKEYBYTES
@@ -131,10 +134,8 @@ namespace ColumnLynx::Net::TCP {
                 mHandler->socket().close(ec);
                 mConnected = false;
                 
-                mGlobalKeyRef = nullptr;
-                if (mSessionIDRef) {
-                    *mSessionIDRef = 0;
-                }
+                ClientSession::getInstance().setAESKey({}); // Clear AES key with all zeros
+                ClientSession::getInstance().setSessionID(0);
 
                 return;
             }
@@ -155,9 +156,10 @@ namespace ColumnLynx::Net::TCP {
                     Utils::log("Received server identity. Public Key: " + hexServerPub);
 
                     // Verify pubkey against whitelisted_keys
-                    std::vector<std::string> whitelistedKeys = Utils::getWhitelistedKeys(mConfigDirPath);
+                    const std::string& configPath = ClientSession::getInstance().getConfigPath();
+                    std::vector<std::string> whitelistedKeys = Utils::getWhitelistedKeys(configPath);
                     if (std::find(whitelistedKeys.begin(), whitelistedKeys.end(), Utils::bytesToHexString(mServerPublicKey, 32)) == whitelistedKeys.end()) { // Key verification is handled in later steps of the handshake
-                        if (!mInsecureMode) {
+                        if (!ClientSession::getInstance().isInsecureMode()) {
                             Utils::error("Server public key not in whitelisted_keys. Terminating connection.");
                             disconnect();
                             return;
@@ -193,16 +195,14 @@ namespace ColumnLynx::Net::TCP {
 
                         // Generate AES key and send confirmation
                         mConnectionAESKey = Utils::LibSodiumWrapper::generateRandom256Bit();
-                        if (mGlobalKeyRef) { // Copy to the global reference
-                            std::copy(mConnectionAESKey.begin(), mConnectionAESKey.end(), mGlobalKeyRef->begin());
-                        }
+                        ClientSession::getInstance().setAESKey(mConnectionAESKey);
                         AsymNonce nonce{};
                         randombytes_buf(nonce.data(), nonce.size());
 
                         // TODO: This is pretty redundant, it should return the required type directly
                         std::array<uint8_t, 32> arrayPrivateKey;
-                        std::copy(mLibSodiumWrapper->getXPrivateKey(),
-                                  mLibSodiumWrapper->getXPrivateKey() + 32,
+                        std::copy(ClientSession::getInstance().getSodiumWrapper()->getXPrivateKey(),
+                                  ClientSession::getInstance().getSodiumWrapper()->getXPrivateKey() + 32,
                                   arrayPrivateKey.begin());
 
                         std::vector<uint8_t> encr = Utils::LibSodiumWrapper::encryptAsymmetric(
@@ -245,19 +245,18 @@ namespace ColumnLynx::Net::TCP {
                     std::memcpy(&mConnectionSessionID, decrypted.data(), sizeof(mConnectionSessionID));
                     std::memcpy(&mTunConfig, decrypted.data() + sizeof(mConnectionSessionID), sizeof(Protocol::TunConfig));
 
-                    mConnectionSessionID = Utils::cbe64toh(mConnectionSessionID);
+                    mConnectionSessionID = ntohl(mConnectionSessionID);
 
                     Utils::log("Connection established with Session ID: " + std::to_string(mConnectionSessionID));
                 
-                    if (mSessionIDRef) { // Copy to the global reference
-                        *mSessionIDRef = mConnectionSessionID;
-                    }
+                    ClientSession::getInstance().setSessionID(mConnectionSessionID);
 
                     uint32_t clientIP = ntohl(mTunConfig.clientIP);
                     uint32_t serverIP = ntohl(mTunConfig.serverIP);
                     uint8_t prefixLen = mTunConfig.prefixLength;
                     uint16_t mtu = mTunConfig.mtu;
 
+                    const auto& mTun = ClientSession::getInstance().getVirtualInterface();
                     if (mTun) {
                         mTun->configureIP(clientIP, serverIP, prefixLen, mtu);
                     }

src/client/net/udp/udp_client.cpp

@@ -1,5 +1,5 @@
 // udp_client.cpp - UDP Client for ColumnLynx
-// Copyright (C) 2025 DcruBro
+// Copyright (C) 2026 DcruBro
 // Distributed under the terms of the GNU General Public License, either version 2 only or version 3. See LICENSES/ for details.
 
 #include <columnlynx/client/net/udp/udp_client.hpp>
@@ -46,9 +46,14 @@ namespace ColumnLynx::Net::UDP {
 
     void UDPClient::sendMessage(const std::string& data) {
         UDPPacketHeader hdr{};
-        randombytes_buf(hdr.nonce.data(), hdr.nonce.size());
+        uint8_t nonce[12];
+        uint32_t prefix = ClientSession::getInstance().getNoncePrefix();
+        uint64_t sendCount = ClientSession::getInstance().getSendCount();
+        memcpy(nonce, &prefix, sizeof(uint32_t)); // Prefix nonce with client-specific random value
+        memcpy(nonce + sizeof(uint32_t), &sendCount, sizeof(uint64_t)); // Use send count as nonce suffix to ensure uniqueness
+        std::copy_n(nonce, 12, hdr.nonce.data());
 
-        if (mAesKeyRef == nullptr || mSessionIDRef == nullptr) {
+        if (ClientSession::getInstance().getAESKey().empty() || ClientSession::getInstance().getSessionID() == 0) {
             Utils::error("UDP Client AES key or Session ID reference is null!");
             return;
         }
@@ -57,24 +62,28 @@ namespace ColumnLynx::Net::UDP {
 
         auto encryptedPayload = Utils::LibSodiumWrapper::encryptMessage(
             reinterpret_cast<const uint8_t*>(data.data()), data.size(),
-            *mAesKeyRef, hdr.nonce, "udp-data"
+            ClientSession::getInstance().getAESKey(), hdr.nonce, "udp-data"
             //std::string(reinterpret_cast<const char*>(&mSessionIDRef), sizeof(uint64_t))
         );
 
         std::vector<uint8_t> packet;
-        packet.reserve(sizeof(UDPPacketHeader) + sizeof(uint64_t) + encryptedPayload.size());
+        packet.reserve(sizeof(UDPPacketHeader) + encryptedPayload.size());
         packet.insert(packet.end(), 
             reinterpret_cast<uint8_t*>(&hdr),
             reinterpret_cast<uint8_t*>(&hdr) + sizeof(UDPPacketHeader)
         );
+        uint32_t sessionID = static_cast<uint32_t>(ClientSession::getInstance().getSessionID());
+        uint32_t sessionIDNet = sessionID;
         packet.insert(packet.end(),
-            reinterpret_cast<uint8_t*>(mSessionIDRef.get()),
-            reinterpret_cast<uint8_t*>(mSessionIDRef.get()) + sizeof(uint64_t)
+            reinterpret_cast<uint8_t*>(&sessionIDNet),
+            reinterpret_cast<uint8_t*>(&sessionIDNet) + sizeof(uint32_t)
         );
         packet.insert(packet.end(), encryptedPayload.begin(), encryptedPayload.end());
 
         mSocket.send_to(asio::buffer(packet), mRemoteEndpoint);
         Utils::debug("Sent UDP packet of size " + std::to_string(packet.size()));
+
+        ClientSession::getInstance().incrementSendCount();
     }
 
     void UDPClient::stop() {
@@ -107,7 +116,7 @@ namespace ColumnLynx::Net::UDP {
     }
 
     void UDPClient::mHandlePacket(std::size_t bytes) {
-        if (bytes < sizeof(UDPPacketHeader) + sizeof(uint64_t)) {
+        if (bytes < sizeof(UDPPacketHeader) + sizeof(uint32_t)) {
             Utils::warn("UDP Client received packet too small to process.");
             return;
         }
@@ -117,27 +126,28 @@ namespace ColumnLynx::Net::UDP {
         std::memcpy(&hdr, mRecvBuffer.data(), sizeof(UDPPacketHeader));
 
         // Parse session ID
-        uint64_t sessionID;
-        std::memcpy(&sessionID, mRecvBuffer.data() + sizeof(UDPPacketHeader), sizeof(uint64_t));
+        uint32_t sessionIDNet;
+        std::memcpy(&sessionIDNet, mRecvBuffer.data() + sizeof(UDPPacketHeader), sizeof(uint32_t));
+        uint32_t sessionID = ntohl(sessionIDNet);
 
-        if (sessionID != *mSessionIDRef) {
-            Utils::warn("Got packet that isn't for me! Dropping!");
+        if (sessionID != ClientSession::getInstance().getSessionID()) {
+            Utils::warn("This packet that isn't for me! Dropping!");
             return;
         }
 
         // Decrypt payload
         std::vector<uint8_t> ciphertext(
-            mRecvBuffer.begin() + sizeof(UDPPacketHeader) + sizeof(uint64_t),
+            mRecvBuffer.begin() + sizeof(UDPPacketHeader) + sizeof(uint32_t),
             mRecvBuffer.begin() + bytes
         );
 
-        if (mAesKeyRef == nullptr) {
+        if (ClientSession::getInstance().getAESKey().empty()) {
             Utils::error("UDP Client AES key reference is null!");
             return;
         }
 
         std::vector<uint8_t> plaintext = Utils::LibSodiumWrapper::decryptMessage(
-            ciphertext.data(), ciphertext.size(), *mAesKeyRef, hdr.nonce, "udp-data"
+            ciphertext.data(), ciphertext.size(), ClientSession::getInstance().getAESKey(), hdr.nonce, "udp-data"
             //std::string(reinterpret_cast<const char*>(&mSessionIDRef), sizeof(uint64_t))
         );
 
@@ -149,6 +159,7 @@ namespace ColumnLynx::Net::UDP {
         Utils::debug("UDP Client received packet from " + mRemoteEndpoint.address().to_string() + " - Packet size: " + std::to_string(bytes));
 
         // Write to TUN
+        const auto& mTunRef = ClientSession::getInstance().getVirtualInterface();
         if (mTunRef) {
             mTunRef->writePacket(plaintext);
         }

src/common/libsodium_wrapper.cpp

@@ -1,5 +1,5 @@
 // libsodium_wrapper.cpp - Libsodium Wrapper for ColumnLynx
-// Copyright (C) 2025 DcruBro
+// Copyright (C) 2026 DcruBro
 // Distributed under the terms of the GNU General Public License, either version 2 only or version 3. See LICENSES/ for details.
 
 #include <columnlynx/common/libsodium_wrapper.hpp>

src/common/session_registry.cpp

@@ -1,17 +1,17 @@
 // session_registry.cpp - Session Registry for ColumnLynx
-// Copyright (C) 2025 DcruBro
+// Copyright (C) 2026 DcruBro
 // Distributed under the terms of the GNU General Public License, either version 2 only or version 3. See LICENSES/ for details.
 
 #include <columnlynx/common/net/session_registry.hpp>
 
 namespace ColumnLynx::Net {
-    void SessionRegistry::put(uint64_t sessionID, std::shared_ptr<SessionState> state) {
+    void SessionRegistry::put(uint32_t sessionID, std::shared_ptr<SessionState> state) {
         std::unique_lock lock(mMutex);
         mSessions[sessionID] = std::move(state);
         mIPSessions[mSessions[sessionID]->clientTunIP] = mSessions[sessionID];
     }
 
-    std::shared_ptr<const SessionState> SessionRegistry::get(uint64_t sessionID) const {
+    std::shared_ptr<const SessionState> SessionRegistry::get(uint32_t sessionID) const {
         std::shared_lock lock(mMutex);
         auto it = mSessions.find(sessionID);
         return (it == mSessions.end()) ? nullptr : it->second;
@@ -23,14 +23,14 @@ namespace ColumnLynx::Net {
         return (it == mIPSessions.end()) ? nullptr : it->second;
     }
 
-    std::unordered_map<uint64_t, std::shared_ptr<SessionState>> SessionRegistry::snapshot() const {
-        std::unordered_map<uint64_t, std::shared_ptr<SessionState>> snap;
+    std::unordered_map<uint32_t, std::shared_ptr<SessionState>> SessionRegistry::snapshot() const {
+        std::unordered_map<uint32_t, std::shared_ptr<SessionState>> snap;
         std::shared_lock lock(mMutex);
         snap = mSessions;
         return snap;
     }
 
-    void SessionRegistry::erase(uint64_t sessionID) {
+    void SessionRegistry::erase(uint32_t sessionID) {
         std::unique_lock lock(mMutex);
         mSessions.erase(sessionID);
     }
@@ -60,6 +60,11 @@ namespace ColumnLynx::Net {
         return static_cast<int>(mSessions.size());
     }
 
+    bool SessionRegistry::exists(uint32_t sessionID) const {
+        std::shared_lock lock(mMutex);
+        return mSessions.find(sessionID) != mSessions.end();
+    }
+    
     uint32_t SessionRegistry::getFirstAvailableIP(uint32_t baseIP, uint8_t mask) const {
         std::shared_lock lock(mMutex);
 
@@ -77,7 +82,7 @@ namespace ColumnLynx::Net {
         return 0;
     }
 
-    void SessionRegistry::lockIP(uint64_t sessionID, uint32_t ip) {
+    void SessionRegistry::lockIP(uint32_t sessionID, uint32_t ip) {
         std::unique_lock lock(mMutex);
         mSessionIPs[sessionID] = ip;
         
@@ -87,7 +92,7 @@ namespace ColumnLynx::Net {
         mIPSessions[ip] = mSessions.find(sessionID)->second;
     }
 
-    void SessionRegistry::deallocIP(uint64_t sessionID) {
+    void SessionRegistry::deallocIP(uint32_t sessionID) {
         std::unique_lock lock(mMutex);
     
         auto it = mSessionIPs.find(sessionID);

src/common/tcp_message_handler.cpp

@@ -1,5 +1,5 @@
 // tcp_message_handler.cpp - TCP Message Handler for ColumnLynx
-// Copyright (C) 2025 DcruBro
+// Copyright (C) 2026 DcruBro
 // Distributed under the terms of the GNU General Public License, either version 2 only or version 3. See LICENSES/ for details.
 
 #include <columnlynx/common/net/tcp/tcp_message_handler.hpp>

src/common/utils.cpp

@@ -1,29 +1,65 @@
 // utils.cpp - Utility functions for ColumnLynx
-// Copyright (C) 2025 DcruBro
+// Copyright (C) 2026 DcruBro
 // Distributed under the terms of the GNU General Public License, either version 2 only or version 3. See LICENSES/ for details.
 
 #include <columnlynx/common/utils.hpp>
 
 namespace ColumnLynx::Utils {
+    std::string unixMillisToISO8601(uint64_t unixMillis, bool local) {
+        using namespace std::chrono;
+
+        // Convert milliseconds since epoch to system_clock::time_point
+        system_clock::time_point tp = system_clock::time_point(milliseconds(unixMillis));
+
+        // Convert to time_t for localtime conversion
+        std::time_t tt = system_clock::to_time_t(tp);
+        std::tm localTm;
+
+        if (local) {
+#ifdef _WIN32
+        localtime_s(&localTm, &tt);
+#else
+        localtime_r(&tt, &localTm);
+#endif
+        } else {
+#ifdef _WIN32
+        gmtime_s(&localTm, &tt);
+#else
+        gmtime_r(&tt, &localTm);
+#endif
+        }
+
+        // Format the time to ISO 8601
+        char buffer[30];
+        std::strftime(buffer, sizeof(buffer), "%Y-%m-%dT%H:%M:%S", &localTm);
+
+        // Append milliseconds
+        auto ms = duration_cast<milliseconds>(tp.time_since_epoch()) % 1000;
+        char iso8601[34];
+        std::snprintf(iso8601, sizeof(iso8601), "%s.%03lld", buffer, static_cast<long long>(ms.count()));
+
+        return std::string(iso8601);
+    }
+
     void log(const std::string &msg) {
         uint64_t now = std::chrono::duration_cast<std::chrono::milliseconds>(std::chrono::system_clock::now().time_since_epoch()).count();
-        std::cout << "\033[0m[" << std::to_string(now) << " LOG] " << msg << std::endl;
+        std::cout << "\033[0m[" << unixMillisToISO8601(now) << " LOG] " << msg << std::endl;
     }
 
     void warn(const std::string &msg) {
         uint64_t now = std::chrono::duration_cast<std::chrono::milliseconds>(std::chrono::system_clock::now().time_since_epoch()).count();
-        std::cerr << "\033[33m[" << std::to_string(now) << " WARN] " << msg << "\033[0m" << std::endl;
+        std::cerr << "\033[33m[" << unixMillisToISO8601(now) << " WARN] " << msg << "\033[0m" << std::endl;
     }
 
     void error(const std::string &msg) {
         uint64_t now = std::chrono::duration_cast<std::chrono::milliseconds>(std::chrono::system_clock::now().time_since_epoch()).count();
-        std::cerr << "\033[31m[" << std::to_string(now) << " ERROR] " << msg << "\033[0m" << std::endl;
+        std::cerr << "\033[31m[" << unixMillisToISO8601(now) << " ERROR] " << msg << "\033[0m" << std::endl;
     }
 
     void debug(const std::string &msg) {
 #if DEBUG || _DEBUG
         uint64_t now = std::chrono::duration_cast<std::chrono::milliseconds>(std::chrono::system_clock::now().time_since_epoch()).count();
-        std::cerr << "\033[95m[" << std::to_string(now) << " DEBUG] " << msg << "\033[0m" << std::endl;
+        std::cerr << "\033[95m[" << unixMillisToISO8601(now) << " DEBUG] " << msg << "\033[0m" << std::endl;
 #else
         return;
 #endif
@@ -49,7 +85,7 @@ namespace ColumnLynx::Utils {
     }
 
     std::string getVersion() {
-        return "1.0.0";
+        return "1.1.0";
     }
 
     unsigned short serverPort() {
@@ -57,7 +93,7 @@ namespace ColumnLynx::Utils {
     }
 
     unsigned char protocolVersion() {
-        return 1;
+        return 2;
     }
 
     std::string bytesToHexString(const uint8_t* bytes, size_t length) {
@@ -115,8 +151,11 @@ namespace ColumnLynx::Utils {
         }
 
         std::string line;
-
         while (std::getline(file, line)) {
+            // Convert to upper case to align with the bytesToHexString() output
+            for (int i = 0; i < line.length(); i++) {
+                line[i] = toupper(line[i]);
+            }
             out.push_back(line);
         }
 

src/common/virtual_interface.cpp

@@ -1,5 +1,5 @@
 // virtual_interface.cpp - Virtual Interface for Network Communication
-// Copyright (C) 2025 DcruBro
+// Copyright (C) 2026 DcruBro
 // Distributed under the terms of the GNU General Public License, either version 2 only or version 3. See LICENSES/ for details.
 
 #include <columnlynx/common/net/virtual_interface.hpp>
@@ -433,41 +433,66 @@ namespace ColumnLynx::Net {
                                        uint16_t mtu)
     {
     #ifdef _WIN32
-        std::string ip  = ipv4ToString(clientIP);
-        std::string gw  = ipv4ToString(serverIP);
-        std::string mask;
+        // Interface alias → LUID → Index
+        std::wstring ifAlias(mIfName.begin(), mIfName.end());
 
-        // Convert prefixLen → subnet mask
-        uint32_t maskInt = (prefixLen == 0) ? 0 : (0xFFFFFFFF << (32 - prefixLen));
-        mask = ipv4ToString(maskInt);
+        NET_LUID luid;
+        if (ConvertInterfaceAliasToLuid(ifAlias.c_str(), &luid) != NO_ERROR)
+            return false;
 
-        // Calculate network address from IP and mask
-        uint32_t networkInt = (clientIP & maskInt);
-        std::string network = ipv4ToString(networkInt);
+        NET_IFINDEX ifIndex;
+        if (ConvertInterfaceLuidToIndex(&luid, &ifIndex) != NO_ERROR)
+            return false;
 
-        char cmd[512];
+        // ssign IPv4 address + prefix
+        MIB_UNICASTIPADDRESS_ROW addr;
+        InitializeUnicastIpAddressEntry(&addr);
 
-        // 1. Set the static IP + mask + gateway
-        snprintf(cmd, sizeof(cmd),
-            "netsh interface ip set address name=\"%s\" static %s %s %s",
-            mIfName.c_str(), ip.c_str(), mask.c_str(), gw.c_str()
-        );
-        system(cmd);
+        addr.InterfaceIndex = ifIndex;
+        addr.Address.si_family = AF_INET;
+        addr.Address.Ipv4.sin_addr.s_addr = htonl(clientIP);
+        addr.OnLinkPrefixLength = prefixLen;
+        addr.DadState = IpDadStatePreferred;
 
-        // 2. Set MTU (separate command)
-        snprintf(cmd, sizeof(cmd),
-            "netsh interface ipv4 set subinterface \"%s\" mtu=%u store=persistent",
-            mIfName.c_str(), mtu
-        );
-        system(cmd);
+        if (CreateUnicastIpAddressEntry(&addr) != NO_ERROR)
+            return false;
 
-        // 3. Add route for the VPN network to go through the TUN interface
-        // This is critical: tells Windows to send packets destined for the server/network through the TUN interface
-        snprintf(cmd, sizeof(cmd),
-            "netsh routing ip add persistentroute dest=%s/%d name=\"%s\" nexthopcfg=%s",
-            network.c_str(), prefixLen, mIfName.c_str(), gw.c_str()
-        );
-        system(cmd);
+        // Set MTU
+        MIB_IFROW ifRow;
+        ifRow.dwIndex = ifIndex;
+
+        if (GetIfEntry(&ifRow) != NO_ERROR)
+            return false;
+
+        ifRow.dwMtu = mtu;
+
+        if (SetIfEntry(&ifRow) != NO_ERROR)
+            return false;
+
+        // Add persistent route for VPN network via this interface
+        uint32_t mask =
+            (prefixLen == 0) ? 0 : (0xFFFFFFFFu << (32 - prefixLen));
+        uint32_t network = clientIP & mask;
+
+        MIB_IPFORWARD_ROW2 route;
+        InitializeIpForwardEntry(&route);
+
+        route.InterfaceIndex = ifIndex;
+        route.DestinationPrefix.Prefix.si_family = AF_INET;
+        route.DestinationPrefix.Prefix.Ipv4.sin_addr.s_addr = htonl(network);
+        route.DestinationPrefix.PrefixLength = prefixLen;
+
+        route.NextHop.si_family = AF_INET;
+        route.NextHop.Ipv4.sin_addr.s_addr = 0;
+
+        route.Metric = 1;
+        route.Protocol = static_cast<NL_ROUTE_PROTOCOL>(MIB_IPPROTO_NETMGMT);
+        route.ValidLifetime = 0xFFFFFFFF;
+        route.PreferredLifetime = 0xFFFFFFFF;
+
+        DWORD r = CreateIpForwardEntry2(&route);
+        if (r != NO_ERROR && r != ERROR_OBJECT_ALREADY_EXISTS)
+            return false;
 
         return true;
     #else

src/server/main.cpp

@@ -1,5 +1,5 @@
 // main.cpp - Server entry point for ColumnLynx
-// Copyright (C) 2025 DcruBro
+// Copyright (C) 2026 DcruBro
 // Distributed under the terms of the GNU General Public License, either version 2 only or version 3. See LICENSES/ for details.
 
 #include <asio.hpp>
@@ -15,6 +15,7 @@
 #include <unordered_map>
 #include <cxxopts.hpp>
 #include <columnlynx/common/net/virtual_interface.hpp>
+#include <columnlynx/server/server_session.hpp>
 
 #if defined(__WIN32__)
 #include <windows.h>
@@ -55,7 +56,7 @@ int main(int argc, char** argv) {
         if (optionsObj.count("help")) {
             std::cout << options.help() << std::endl;
             std::cout << "This software is licensed under the GPLv2-only license OR the GPLv3 license.\n";
-            std::cout << "Copyright (C) 2025, The ColumnLynx Contributors.\n";
+            std::cout << "Copyright (C) 2026, The ColumnLynx Contributors.\n";
             std::cout << "This software is provided under ABSOLUTELY NO WARRANTY, to the extent permitted by law.\n";
             return 0;
         }
@@ -69,6 +70,8 @@ int main(int argc, char** argv) {
         //WintunInitialize();
 #endif
 
+        struct ServerState serverState{};
+
         // Get the config path, ENV > CLI > /etc/columnlynx
         std::string configPath = optionsObj["config-dir"].as<std::string>();
         const char* envConfigPath = std::getenv("COLUMNLYNX_CONFIG_DIR");
@@ -84,11 +87,23 @@ int main(int argc, char** argv) {
             #endif
         }
 
-        std::unordered_map<std::string, std::string> config = Utils::getConfigMap(configPath + "server_config");
+        serverState.configPath = configPath;
+
+#if defined(DEBUG)
+        std::unordered_map<std::string, std::string> config = Utils::getConfigMap(configPath + "server_config", { "NETWORK", "SUBNET_MASK" });
+#else
+        // A production server should never use random keys. If the config file cannot be read or does not contain keys, the server will fail to start.
+        std::unordered_map<std::string, std::string> config = Utils::getConfigMap(configPath + "server_config", { "NETWORK", "SUBNET_MASK", "SERVER_PUBLIC_KEY", "SERVER_PRIVATE_KEY" });
+#endif
+
+        serverState.serverConfig = config;
 
         std::shared_ptr<VirtualInterface> tun = std::make_shared<VirtualInterface>(optionsObj["interface"].as<std::string>());
         log("Using virtual interface: " + tun->getName());
 
+        // Store a reference to the tun in the serverState, it will increment and keep a safe reference (we love shared_ptrs)
+        serverState.virtualInterface = tun;
+
         // Generate a temporary keypair, replace with actual CA signed keys later (Note, these are stored in memory)
         std::shared_ptr<LibSodiumWrapper> sodiumWrapper = std::make_shared<LibSodiumWrapper>();
 
@@ -117,19 +132,24 @@ int main(int argc, char** argv) {
 
         log("Server public key: " + bytesToHexString(sodiumWrapper->getPublicKey(), crypto_sign_PUBLICKEYBYTES));
 
-        std::shared_ptr<bool> hostRunning = std::make_shared<bool>(true);
+        serverState.sodiumWrapper = sodiumWrapper;
+        serverState.ipv4Only = ipv4Only;
+        serverState.hostRunning = true;
+
+        // Store the global state; from now on, it should only be accessed through the ServerSession singleton, which will ensure thread safety with its internal mutex
+        ServerSession::getInstance().setServerState(std::make_shared<ServerState>(std::move(serverState)));
 
         asio::io_context io;
 
-        auto server = std::make_shared<TCPServer>(io, serverPort(), sodiumWrapper, hostRunning, configPath, ipv4Only);
-        auto udpServer = std::make_shared<UDPServer>(io, serverPort(), hostRunning, ipv4Only, tun);
+        auto server = std::make_shared<TCPServer>(io, serverPort());
+        auto udpServer = std::make_shared<UDPServer>(io, serverPort());
 
         asio::signal_set signals(io, SIGINT, SIGTERM);
         signals.async_wait([&](const std::error_code&, int) {
             log("Received termination signal. Shutting down server gracefully.");
             done = 1;
             asio::post(io, [&]() {
-                *hostRunning = false;
+                ServerSession::getInstance().setHostRunning(false);
                 server->stop();
                 udpServer->stop();
             });
@@ -153,15 +173,28 @@ int main(int argc, char** argv) {
             }
 
             const uint8_t* ip = packet.data();
-            uint32_t dstIP = ntohl(*(uint32_t*)(ip + 16)); // IPv4 destination address offset in IPv6-mapped header
+            uint32_t srcIP = ntohl(*(uint32_t*)(ip + 12)); // IPv4 source address offset
+            uint32_t dstIP = ntohl(*(uint32_t*)(ip + 16)); // IPv4 destination address offset
         
-            auto session = SessionRegistry::getInstance().getByIP(dstIP);
-            if (!session) {
-                Utils::warn("TUN: No session found for destination IP " + VirtualInterface::ipv4ToString(dstIP));
+            // First, check if destination IP is a registered client (e.g., server responding to client or client-to-client)
+            auto dstSession = SessionRegistry::getInstance().getByIP(dstIP);
+            if (dstSession) {
+                // Destination is a registered client, forward to that client's session
+                udpServer->sendData(dstSession->sessionID, std::string(packet.begin(), packet.end()));
                 continue;
             }
 
-            udpServer->sendData(session->sessionID, std::string(packet.begin(), packet.end()));
+            // Destination is not a registered client, check if source is (for external routing)
+            auto srcSession = SessionRegistry::getInstance().getByIP(srcIP);
+            if (srcSession) {
+                // Source is a registered client, write to TUN interface to forward to external destination
+                tun->writePacket(packet);
+                continue;
+            }
+
+            // Neither source nor destination is registered, drop the packet
+            Utils::warn("TUN: No session found for source IP " + VirtualInterface::ipv4ToString(srcIP) + 
+                       " or destination IP " + VirtualInterface::ipv4ToString(dstIP));
         }
 
         log("Shutting down server...");

src/server/net/tcp/tcp_connection.cpp

@@ -1,5 +1,5 @@
 // tcp_connection.cpp - TCP Connection for ColumnLynx
-// Copyright (C) 2025 DcruBro
+// Copyright (C) 2026 DcruBro
 // Distributed under the terms of the GNU General Public License, either version 2 only or version 3. See LICENSES/ for details.
 
 #include <columnlynx/server/net/tcp/tcp_connection.hpp>
@@ -66,7 +66,7 @@ namespace ColumnLynx::Net::TCP {
         Utils::log("Initiated graceful disconnect (half-close) to " + mRemoteIP);
     }
 
-    uint64_t TCPConnection::getSessionID() const {
+    uint32_t TCPConnection::getSessionID() const {
         return mConnectionSessionID;
     }
 
@@ -145,7 +145,7 @@ namespace ColumnLynx::Net::TCP {
                 
                 Utils::debug("Key attempted connect: " + Utils::bytesToHexString(signPk.data(), signPk.size()));
 
-                std::vector<std::string> whitelistedKeys = Utils::getWhitelistedKeys(mConfigDirPath);
+                std::vector<std::string> whitelistedKeys = Utils::getWhitelistedKeys(ServerSession::getInstance().getConfigPath());
 
                 if (std::find(whitelistedKeys.begin(), whitelistedKeys.end(), Utils::bytesToHexString(signPk.data(), signPk.size())) == whitelistedKeys.end()) {
                     Utils::warn("Non-whitelisted client attempted to connect, terminating. Client IP: " + reqAddr);
@@ -156,7 +156,7 @@ namespace ColumnLynx::Net::TCP {
 
                 Utils::debug("Client " + reqAddr + " passed authorized_keys");
 
-                mHandler->sendMessage(ServerMessageType::HANDSHAKE_IDENTIFY, Utils::uint8ArrayToString(mLibSodiumWrapper->getPublicKey(), crypto_sign_PUBLICKEYBYTES)); // This public key should always exist
+                mHandler->sendMessage(ServerMessageType::HANDSHAKE_IDENTIFY, Utils::uint8ArrayToString(ServerSession::getInstance().getSodiumWrapper()->getPublicKey(), crypto_sign_PUBLICKEYBYTES)); // This public key should always exist
                 break;
             }
             case ClientMessageType::HANDSHAKE_CHALLENGE: {
@@ -169,7 +169,7 @@ namespace ColumnLynx::Net::TCP {
                 // Sign the challenge
                 Signature sig = Utils::LibSodiumWrapper::signMessage(
                     challengeData, sizeof(challengeData),
-                    mLibSodiumWrapper->getPrivateKey()
+                    ServerSession::getInstance().getSodiumWrapper()->getPrivateKey()
                 );
 
                 mHandler->sendMessage(ServerMessageType::HANDSHAKE_CHALLENGE_RESPONSE, Utils::uint8ArrayToString(sig.data(), sig.size())); // Placeholder response
@@ -191,8 +191,8 @@ namespace ColumnLynx::Net::TCP {
                 std::memcpy(ciphertext.data(), data.data() + nonce.size(), ciphertext.size());
                 try {
                     std::array<uint8_t, 32> arrayPrivateKey;
-                    std::copy(mLibSodiumWrapper->getXPrivateKey(),
-                              mLibSodiumWrapper->getXPrivateKey() + 32,
+                    std::copy(ServerSession::getInstance().getSodiumWrapper()->getXPrivateKey(),
+                              ServerSession::getInstance().getSodiumWrapper()->getXPrivateKey() + 32,
                               arrayPrivateKey.begin());
 
                     // Decrypt the AES key using the client's public key and server's private key
@@ -211,14 +211,18 @@ namespace ColumnLynx::Net::TCP {
 
                     std::memcpy(mConnectionAESKey.data(), decrypted.data(), decrypted.size());
 
-                    // Make a Session ID
-                    randombytes_buf(&mConnectionSessionID, sizeof(mConnectionSessionID));
+                    // Make a Session ID - unique and not zero (zero is reserved for invalid sessions)
+                    do {
+                        randombytes_buf(&mConnectionSessionID, sizeof(mConnectionSessionID));
+                    } while (SessionRegistry::getInstance().exists(mConnectionSessionID) || mConnectionSessionID == 0); // Regenerate if it already exists or is zero (zero is reserved for invalid sessions)
 
                     // Encrypt the Session ID with the established AES key (using symmetric encryption, nonce can be all zeros for this purpose)
                     Nonce symNonce{}; // All zeros
 
-                    std::string networkString = mRawServerConfig->find("NETWORK")->second; // The load check guarantees that this value exists
-                    uint8_t configMask = std::stoi(mRawServerConfig->find("SUBNET_MASK")->second); // Same deal here
+                    const auto& serverConfig = ServerSession::getInstance().getRawServerConfig();
+
+                    std::string networkString = serverConfig.find("NETWORK")->second; // The load check guarantees that this value exists
+                    uint8_t configMask = std::stoi(serverConfig.find("SUBNET_MASK")->second); // Same deal here
 
                     uint32_t baseIP = Net::VirtualInterface::stringToIpv4(networkString);
 
@@ -245,11 +249,11 @@ namespace ColumnLynx::Net::TCP {
                     tunConfig.dns1 = htonl(0x08080808);    // 8.8.8.8
                     tunConfig.dns2 = 0;
 
-                    uint64_t sessionIDNet = Utils::chtobe64(mConnectionSessionID);
+                    uint32_t sessionIDNet = htonl(mConnectionSessionID);
 
-                    std::vector<uint8_t> payload(sizeof(uint64_t) + sizeof(tunConfig));
-                    std::memcpy(payload.data(), &sessionIDNet, sizeof(uint64_t));
-                    std::memcpy(payload.data() + sizeof(uint64_t), &tunConfig, sizeof(tunConfig));
+                    std::vector<uint8_t> payload(sizeof(uint32_t) + sizeof(tunConfig));
+                    std::memcpy(payload.data(), &sessionIDNet, sizeof(uint32_t));
+                    std::memcpy(payload.data() + sizeof(uint32_t), &tunConfig, sizeof(tunConfig));
 
                     std::vector<uint8_t> encryptedPayload = Utils::LibSodiumWrapper::encryptMessage(
                         payload.data(), payload.size(),
@@ -261,6 +265,7 @@ namespace ColumnLynx::Net::TCP {
                     // Add to session registry
                     Utils::log("Handshake with " + reqAddr + " completed successfully. Session ID assigned (" + std::to_string(mConnectionSessionID) + ").");
                     auto session = std::make_shared<SessionState>(mConnectionAESKey, std::chrono::hours(12), clientIP, htonl(0x0A0A0001), mConnectionSessionID);
+                    session->setBaseNonce(); // Set it
                     SessionRegistry::getInstance().put(mConnectionSessionID, std::move(session));
                     SessionRegistry::getInstance().lockIP(mConnectionSessionID, clientIP);
 

src/server/net/tcp/tcp_server.cpp

@@ -1,5 +1,5 @@
 // tcp_server.cpp - TCP Server for ColumnLynx
-// Copyright (C) 2025 DcruBro
+// Copyright (C) 2026 DcruBro
 // Distributed under the terms of the GNU General Public License, either version 2 only or version 3. See LICENSES/ for details.
 
 #include <columnlynx/server/net/tcp/tcp_server.hpp>
@@ -27,16 +27,13 @@ namespace ColumnLynx::Net::TCP {
                     }
                     Utils::error("Accept failed: " + ec.message());
                     // Try again only if still running
-                    if (mHostRunning && *mHostRunning && mAcceptor.is_open())
+                    if (ServerSession::getInstance().isHostRunning() && mAcceptor.is_open())
                         mStartAccept();
                     return;
                 }
 
                 auto client = TCPConnection::create(
                     std::move(socket),
-                    mSodiumWrapper,
-                    &mRawServerConfig,
-                    mConfigDirPath,
                     [this](std::shared_ptr<TCPConnection> c) {
                         mClients.erase(c);
                         Utils::log("Client removed.");
@@ -46,7 +43,7 @@ namespace ColumnLynx::Net::TCP {
                 client->start();
                 Utils::log("Accepted new client connection.");
             
-                if (mHostRunning && *mHostRunning && mAcceptor.is_open())
+                if (ServerSession::getInstance().isHostRunning() && mAcceptor.is_open())
                     mStartAccept();
             }
         );

src/server/net/udp/udp_server.cpp

@@ -1,5 +1,5 @@
 // udp_server.cpp - UDP Server for ColumnLynx
-// Copyright (C) 2025 DcruBro
+// Copyright (C) 2026 DcruBro
 // Distributed under the terms of the GNU General Public License, either version 2 only or version 3. See LICENSES/ for details.
 
 #include <columnlynx/server/net/udp/udp_server.hpp>
@@ -16,26 +16,27 @@ namespace ColumnLynx::Net::UDP {
                 if (ec) {
                     if (ec == asio::error::operation_aborted) return; // Socket closed
                     // Other recv error
-                    if (mHostRunning && *mHostRunning) mStartReceive();
+                    if (ServerSession::getInstance().isHostRunning()) mStartReceive();
                     return;
                 }
                 if (bytes > 0) mHandlePacket(bytes);
-                if (mHostRunning && *mHostRunning) mStartReceive();
+                if (ServerSession::getInstance().isHostRunning()) mStartReceive();
             }
         );
     }
 
     void UDPServer::mHandlePacket(std::size_t bytes) {
-        if (bytes < sizeof(UDPPacketHeader))
+        if (bytes < sizeof(UDPPacketHeader) + sizeof(uint32_t))
             return;
         
         const auto* hdr = reinterpret_cast<UDPPacketHeader*>(mRecvBuffer.data());
 
-        // Get plaintext session ID (assuming first 8 bytes after nonce (header))
-        uint64_t sessionID = 0;
-        std::memcpy(&sessionID, mRecvBuffer.data() + sizeof(UDPPacketHeader), sizeof(uint64_t));
+        // Get plaintext session ID (first 4 bytes after header, in network byte order)
+        uint32_t sessionIDNet = 0;
+        std::memcpy(&sessionIDNet, mRecvBuffer.data() + sizeof(UDPPacketHeader), sizeof(uint32_t));
+        uint32_t sessionID = sessionIDNet; // ntohl(sessionIDNet); --- IGNORE ---
 
-        auto it = mRecvBuffer.begin() + sizeof(UDPPacketHeader) + sizeof(uint64_t);
+        auto it = mRecvBuffer.begin() + sizeof(UDPPacketHeader) + sizeof(uint32_t);
         std::vector<uint8_t> encryptedPayload(it, mRecvBuffer.begin() + bytes);
 
         // Get associated session state
@@ -54,7 +55,7 @@ namespace ColumnLynx::Net::UDP {
                 encryptedPayload.data(), encryptedPayload.size(),
                 session->aesKey,
                 hdr->nonce, "udp-data"
-                //std::string(reinterpret_cast<const char*>(&sessionID), sizeof(uint64_t))
+                //std::string(reinterpret_cast<const char*>(&sessionID), sizeof(uint32_t))
             );
 
             Utils::debug("Passed decryption");
@@ -76,7 +77,7 @@ namespace ColumnLynx::Net::UDP {
         }
     }
 
-    void UDPServer::sendData(const uint64_t sessionID, const std::string& data) {
+    void UDPServer::sendData(uint32_t sessionID, const std::string& data) {
         // Find the IPv4/IPv6 endpoint for the session
         std::shared_ptr<const SessionState> session = SessionRegistry::getInstance().get(sessionID);
         if (!session) {
@@ -92,23 +93,29 @@ namespace ColumnLynx::Net::UDP {
 
         // Prepare packet
         UDPPacketHeader hdr{};
-        randombytes_buf(hdr.nonce.data(), hdr.nonce.size());
+        uint8_t nonce[12];
+        uint32_t prefix = session->noncePrefix;
+        uint64_t sendCount = const_cast<SessionState*>(session.get())->send_ctr.fetch_add(1, std::memory_order_relaxed);
+        memcpy(nonce, &prefix, sizeof(uint32_t)); // Prefix nonce
+        memcpy(nonce + sizeof(uint32_t), &sendCount, sizeof(uint64_t)); // Use send count as nonce suffix to ensure uniqueness
+        std::copy_n(nonce, 12, hdr.nonce.data());
 
         auto encryptedPayload = Utils::LibSodiumWrapper::encryptMessage(
             reinterpret_cast<const uint8_t*>(data.data()), data.size(),
             session->aesKey, hdr.nonce, "udp-data"
-            //std::string(reinterpret_cast<const char*>(&sessionID), sizeof(uint64_t))
+            //std::string(reinterpret_cast<const char*>(&sessionID), sizeof(uint32_t))
         );
 
         std::vector<uint8_t> packet;
-        packet.reserve(sizeof(UDPPacketHeader) +  sizeof(uint64_t) + encryptedPayload.size());
+        packet.reserve(sizeof(UDPPacketHeader) + sizeof(uint32_t) + encryptedPayload.size());
         packet.insert(packet.end(), 
             reinterpret_cast<uint8_t*>(&hdr),
             reinterpret_cast<uint8_t*>(&hdr) + sizeof(UDPPacketHeader)
         );
+        uint32_t sessionIDNet = htonl(sessionID);
         packet.insert(packet.end(),
-            reinterpret_cast<const uint8_t*>(&sessionID),
-            reinterpret_cast<const uint8_t*>(&sessionID) + sizeof(sessionID)
+            reinterpret_cast<const uint8_t*>(&sessionIDNet),
+            reinterpret_cast<const uint8_t*>(&sessionIDNet) + sizeof(sessionIDNet)
         );
         packet.insert(packet.end(), encryptedPayload.begin(), encryptedPayload.end());
 

src/server/server_session.cpp

@@ -0,0 +1,92 @@
+// server_session.cpp - Client Session data for ColumnLynx
+// Copyright (C) 2026 DcruBro
+// Distributed under the terms of the GNU General Public License, either version 2 only or version 3. See LICENSES/ for details.
+
+#include <columnlynx/server/server_session.hpp>
+
+namespace ColumnLynx {
+    std::shared_ptr<ServerState> ServerSession::getServerState() const {
+        std::shared_lock lock(mMutex);
+        return mServerState;
+    }
+
+    void ServerSession::setServerState(std::shared_ptr<ServerState> state) {
+        std::unique_lock lock(mMutex);
+        mServerState = std::move(state);
+    }
+
+    std::shared_ptr<Utils::LibSodiumWrapper> ServerSession::getSodiumWrapper() const {
+        std::shared_lock lock(mMutex);
+        return mServerState ? mServerState->sodiumWrapper : nullptr;
+    }
+
+    const std::string& ServerSession::getConfigPath() const {
+        static const std::string emptyString;
+        std::shared_ptr<ServerState> state = getServerState();
+        return state ? state->configPath : emptyString;
+    }
+
+    const std::unordered_map<std::string, std::string>& ServerSession::getRawServerConfig() const {
+        static const std::unordered_map<std::string, std::string> emptyMap;
+        std::shared_ptr<ServerState> state = getServerState();
+        return state ? state->serverConfig : emptyMap;
+    }
+
+    const std::shared_ptr<Net::VirtualInterface>& ServerSession::getVirtualInterface() const {
+        static const std::shared_ptr<Net::VirtualInterface> nullTun = nullptr;
+        std::shared_ptr<ServerState> state = getServerState();
+        return state ? state->virtualInterface : nullTun;
+    }
+
+    bool ServerSession::isIPv4Only() const {
+        std::shared_ptr<ServerState> state = getServerState();
+        return state ? state->ipv4Only : false;
+    }
+
+    bool ServerSession::isHostRunning() const {
+        std::shared_ptr<ServerState> state = getServerState();
+        return state ? state->hostRunning : false;
+    }
+
+    void ServerSession::setSodiumWrapper(std::shared_ptr<Utils::LibSodiumWrapper> sodiumWrapper) {
+        std::unique_lock lock(mMutex);
+        if (!mServerState)
+            mServerState = std::make_shared<ServerState>();
+        mServerState->sodiumWrapper = std::move(sodiumWrapper);
+    }
+
+    void ServerSession::setConfigPath(const std::string& configPath) {
+        std::unique_lock lock(mMutex);
+        if (!mServerState)
+            mServerState = std::make_shared<ServerState>();
+        mServerState->configPath = configPath;
+    }
+
+    void ServerSession::setRawServerConfig(const std::unordered_map<std::string, std::string>& config) {
+        std::unique_lock lock(mMutex);
+        if (!mServerState)
+            mServerState = std::make_shared<ServerState>();
+        mServerState->serverConfig = config;
+    }
+
+    void ServerSession::setVirtualInterface(std::shared_ptr<Net::VirtualInterface> tun) {
+        std::unique_lock lock(mMutex);
+        if (!mServerState)
+            mServerState = std::make_shared<ServerState>();
+        mServerState->virtualInterface = std::move(tun);
+    }
+
+    void ServerSession::setIPv4Only(bool ipv4Only) {
+        std::unique_lock lock(mMutex);
+        if (!mServerState)
+            mServerState = std::make_shared<ServerState>();
+        mServerState->ipv4Only = ipv4Only;
+    }
+
+    void ServerSession::setHostRunning(bool hostRunning) {
+        std::unique_lock lock(mMutex);
+        if (!mServerState)
+            mServerState = std::make_shared<ServerState>();
+        mServerState->hostRunning = hostRunning;
+    }
+}