Dynamic Network Authentication System (DNAS) was a proprietary

authentication Authentication (from ''authentikos'', "real, genuine", from αὐθέντης ''authentes'', "author") is the act of proving an assertion, such as the identity of a computer system user. In contrast with identification, the act of indicati ...

system created by Sony Computer Entertainment Inc. DNAS retrieved information about a user's hardware and software for authentication,

copy protection Copy protection, also known as content protection, copy prevention and copy restriction, describes measures to enforce copyright by preventing the reproduction of software, films, music, and other media. Copy protection is most commonly found on ...

, account blocking, system, rules, or game management and other purposes. DNAS used a set of codes in a protected area of the game

DVD The DVD (common abbreviation for Digital Video Disc or Digital Versatile Disc) is a digital optical disc data storage format. It was invented and developed in 1995 and first released on November 1, 1996, in Japan. The medium can store any kin ...

together with serial numbers from the console

EEPROM EEPROM (also called E2PROM) stands for electrically erasable programmable read-only memory and is a type of non-volatile memory used in computers, usually integrated in microcontrollers such as smart cards and remote keyless systems, or as a ...

for online

. Game backups or copies using regular

DVD-R DVD recordable and DVD rewritable are optical disc recording technologies. Both terms describe DVD optical discs that can be written to by a DVD recorder, whereas only 'rewritable' discs are able to erase and rewrite data. Data is written ('burne ...

burner Burner may refer to: * Gas burner, coal burner or oil burner, a mechanical device that burns a gas or liquid fuel in a controlled manner ** Laboratory gas burners: *** Bunsen burner *** Meker–Fisher burner *** Teclu burner ** Hot-air balloon de ...

s do not have this protected area, and the games failed to authenticate to the servers. To circumvent this, programs have been made available that

patch Patch or Patches may refer to: Arts, entertainment and media * Patch Johnson, a fictional character from ''Days of Our Lives'' * Patch (''My Little Pony''), a toy * "Patches" (Dickey Lee song), 1962 * "Patches" (Chairmen of the Board song) ...

the client portion of the game to report hardcoded values without attempting to access the protected area of the DVD. This made it possible to play online with game backups and illegal copies. Some games have a double DNAS check to prevent people from patching them. These techniques have been introduced by

Electronic Arts Electronic Arts Inc. (EA) is an American video game company headquartered in Redwood City, California. Founded in May 1982 by Apple employee Trip Hawkins, the company was a pioneer of the early home computer game industry and promoted the d ...

in most of their recent games, but it has not shown any positive results. Many new techniques for authentication were tried, with very little success for the game companies. The DNAS service was terminated on 4 April 2016 for NTSC/U and PAL regions after the last official online game,

Final Fantasy XI also known as ''Final Fantasy XI Online'', is a massively multiplayer online role-playing game (MMORPG), originally developed and published by Squaresoft and then published by Square Enix as the eleventh main installment of the ''Final Fantasy ...

, was taken offline on 31 March 2016, but continued to support NTSC/J PS2 titles and Japanese PSP Store. However unofficial private servers allowed game play on other PS2 games until 4 April. Certain games continued to work beyond 4 April and are still operational thanks to certain workarounds.List of PS2 multiplayer games with servers both running and terminated.
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References

Sony Interactive Entertainment {{videogame-software-stub