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The LoginServer class is the main entry point for the authentication server, managing client connections, account validation, and GameServer registration. Source: org.l2jmobius.loginserver.LoginServer
Location: java/org/l2jmobius/loginserver/LoginServer.java:47

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Overview

LoginServer is a singleton service that:
  • Accepts client connections on port 2106
  • Validates account credentials against the database
  • Manages GameServer registrations on port 9014
  • Enforces flood protection and security policies
  • Handles banned accounts and IP addresses

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Class Structure

public class LoginServer extends FloodProtectorListener

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Key Constants

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PROTOCOL_REV
int
default:"0x0102"
Login protocol revision number (258)
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LOGGER
Logger
Logger instance for LoginServer events

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Initialization Sequence

The LoginServer follows this startup sequence:
1

Database Initialization

DatabaseFactory.init();
Establishes connection pool to the authentication database
2

Thread Pool Setup

ThreadPool.init();
Configures thread pools for handling client connections
3

Login Controller

LoginController.load();
Loads RSA key pairs for password encryption
4

GameServer Table

GameServerTable.getInstance();
Initializes the registry of connected GameServers
5

Ban List Loading

loadBanFile();
Loads banned accounts and IP addresses
6

GameServer Listener

_gameServerListener = new GameServerListener();
_gameServerListener.start();
Starts listening for GameServer connections on port 9014

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Core Methods

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getInstance()

public static LoginServer getInstance()
Returns the singleton LoginServer instance. Returns: The active LoginServer instance

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shutdown()

public void shutdown(boolean restart)
Gracefully shuts down the LoginServer.
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restart
boolean
Whether to restart after shutdown
Behavior:
  1. Stops accepting new connections
  2. Disconnects all active clients
  3. Saves server state to database
  4. Closes database connections
  5. Exits JVM (if not restarting)

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addGameServerLogin()

public void addGameServerLogin(int id, byte[] hexId, String address)
Registers a GameServer with the LoginServer.
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id
int
required
GameServer ID (1-127)
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hexId
byte[]
required
Hexadecimal authentication key
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address
String
required
GameServer IP address

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Configuration

LoginServer is configured through login/config/Server.ini: 
# Network Configuration
LoginHost = 0.0.0.0
LoginPort = 2106

# GameServer Communication
GameServerLoginHost = *
GameServerLoginPort = 9014

# Security
EnableFloodProtection = True
FastConnectionLimit = 15
NormalConnectionTime = 700
FastConnectionTime = 350
MaxConnectionPerIP = 50

# Auto-Create Accounts
AutoCreateAccounts = True

# Scheduled Restart
LoginServerScheduleRestart = False
LoginServerScheduleRestartTime = 24

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Security Features

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Flood Protection

The LoginServer implements several flood protection mechanisms: 
FastConnectionLimit = 15        // Max connections in FastConnectionTime
NormalConnectionTime = 700      // Normal connection interval (ms)
FastConnectionTime = 350        // Fast connection detection window (ms)

MaxConnectionPerIP = 50         // Max simultaneous connections per IP
Prevents IP-based DDoS attacks
Automatically bans IPs after repeated failed login attemptsConfigurable thresholds in LoginConfig.java

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Password Encryption

Client passwords are encrypted using RSA before transmission: 
// RSA key pair generation in LoginController
private void generateRSAKeys() throws GeneralSecurityException
{
    KeyPairGenerator keygen = KeyPairGenerator.getInstance("RSA");
    keygen.initialize(new RSAKeyGenParameterSpec(1024, RSAKeyGenParameterSpec.F4));
    _keyPairs = new ScrambledKeyPair[KEYS_SIZE];
    
    for (int i = 0; i < KEYS_SIZE; i++)
    {
        _keyPairs[i] = new ScrambledKeyPair(keygen.generateKeyPair());
    }
}

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Database Schema

LoginServer uses these tables: accounts
  • login - Account username
  • password - Hashed password (SHA-256)
  • access_level - Account privilege level
  • lastactive - Last login timestamp
  • lastIP - Last login IP address
gameservers
  • server_id - GameServer ID (1-127)
  • hexid - Authentication hexadecimal key
  • host - Internal server IP

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Usage Example

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Starting the LoginServer

cd dist/login
./startLoginServer.sh    # Linux/Mac
# or
startLoginServer.bat     # Windows

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Monitoring Logs

tail -f log/java.log
Expected startup output: 
LoginServer is now listening on *:2106
Listening for GameServers on *:9014

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Stopping the Server

# Graceful shutdown
kill -SIGTERM <pid>

# Or use admin command (if configured)
telnet localhost 7001
shutdown
  • GameServer - Game server that connects to LoginServer
  • DatabaseFactory - Database connection management
  • LoginController - Account authentication and validation
  • GameServerTable - Registry of connected GameServers
  • LoginClient - Represents a connected client session

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Troubleshooting

Solution: Check if another service is using the port
sudo lsof -i :2106
netstat -an | grep 2106
Change LoginPort in Server.ini if needed
Solution: Verify GameServer hexid and IP configuration
  1. Check gameservers table in database
  2. Verify GameServerLoginHost and GameServerLoginPort in Server.ini
  3. Ensure firewall allows port 9014
Solution: Check Database.ini configuration
URL = jdbc:mysql://localhost/l2jmobiusc4
Login = l2jmobius
Password = your_password
Test connection:
mysql -u l2jmobius -p l2jmobiusc4
Solution: Enable in Server.ini
AutoCreateAccounts = True
Restart LoginServer for changes to take effect

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Best Practices

Production Deployment:
  • Disable auto-create accounts (AutoCreateAccounts = False)
  • Enable flood protection
  • Use strong database passwords
  • Configure firewall rules (allow 2106 for clients, 9014 for GameServers only)
  • Monitor failed login attempts
  • Schedule regular database backups
  • Use RSA key rotation for enhanced security

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Performance Monitoring

Monitor LoginServer health with these metrics: 
// In LoginServer.java
LOGGER.info("Active connections: " + getConnectionCount());
LOGGER.info("Registered GameServers: " + GameServerTable.getInstance().getRegisteredGameServers().size());
Recommended monitoring:
  • Active connections - Track concurrent users
  • Failed logins per hour - Detect brute force attacks
  • Average login time - Database performance indicator
  • Memory usage - JVM heap monitoring

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