Novel. 1996. Cycle: A maze of reflections
From the publisher:
Read the most famous novel by Sergey Lukianenko. “A maze of reflection” is a fantastic novel number one in the Net. “A maze of reflection” is a handbook of Russian hackers. “A maze of reflection” is a cyber-love and cyber-war, virtual duels and computer adventures – sometimes funny, but often dangerous. You won’t tear yourself away from this book!