DearFTP/DearFTP/Connection/Commands/QuitCommand.cs

namespace DearFTP.Connection.Commands
{
    class QuitCommand : ICommand
    {
        public string[] Aliases { get; } = new string[]
        {
            "QUIT",
            "EXIT"
        };

        public void Execute(Session session, FtpStream stream, string alias, string argument)
        {
            stream.Send(ResponseCode.ServiceClosingConnection, "Goodbye.");
        }
    }
}