BACKUPS IN NETWORKED PCS
SARADA AVADHANAM

1. B. Routine Data Backups Routine Data BackupsEven on stand-alone systems, computer users often make backup copies of files to protect against hardware failure or other physical disruptions. Backup copies can be made on magnetic tape, disks, or cartridges.
1.1. 2. Networked pcs : This can be done with coaxial cable in a local area network, via common telephone lines, or even through a wireless network, using radio frequency (RF) communications. Due to this interconnectivity, it has become more important than ever to ascertain from sources or surveillance what type of system agents will encounter& consider the possibility of off-site storage locations.
2. The following are systems or devices used:
3. FILE SERVER: A file server is a computer on a network that stores the programs and data files shared by the users of the network. A file server acts like a remote disk drive, enabling someone to store information on a computer system other than his own. It can be located in another judicial district from the target machine.
4. ELECTRONIC MAIL: Electronic mail provides for the transmission of messages and files between computers over a communications network. The transmitted messages (and attached files) are either stored at the computer of the addressee (such as someone's personal computer) or at a mail server (a machine dedicated, at least in part, to storing mail). If the undelivered mail is stored on a server, it will remain there until the addressee retrieves it. When people "pick up" e-mail from the mail server, they usually receive only a copy of their mail, and the stored message is maintained in the mail server until the addressee deletes it (some systems allow senders to delete mail on the server before delivery). Of course, deleted mail may sometimes be recovered by undeleting the message (if not yet overwritten) or by obtaining a backup copy (if the server was backed up before the message was deleted).
5. ELECTRONIC BULLETIN BOARD SYSTEMS (BBS): A bulletin board system is a computer dedicated, in whole or in part, to serving as an electronic meeting place. A BBS computer system may contain information, programs, and e-mail, and is set up so that users can dial the bulletin board system, read and leave messages for other users, and download and upload software programs for common use. Some BBSS also have gateways which allow users to connect to other bulletin boards or networks. A BBS can have multiple telephone lines (so that many people can use it at the same time) or a single line where a user's access is first-come, first-served. BBSS can have several levels of access, sometimes called "sub-boards" or "conferences." Access to the different conferences is usually controlled by the system operator with a password system. A single user may have several different passwords, one for each different level or conference. A user may store documents, data, programs, messages, and even photographs in the different levels of the BBS. A bulletin board system may be located anywhere telephone lines go. A pen register on the suspect's phone may reveal the location of these stored files. They forward incoming calls through a simple phone in one spot to their BBS computers somewhere else. We cannot assume that the phone number called by the suspect is always the end of the line.
6. VOICE-MAIL SYSTEMS: A voice-mail system is a complex phone answering machine (computer) which allows individuals to send and receive telephone voice messages to a specific "mailbox" number. A person can call the voice-mail system (often a 1-800 number) and leave a message in a particular person's mailbox, retrieve messages left by other people, or transfer one message to many different mailboxes in a list. Usually, anyone can leave messages, but it takes a password to pick them up or change the initial greeting. The system turns the user's voice into digital data and stores it until the addressee erases it or another message overwrites it. Criminals sometimes use voice mailboxes (especially mailboxes of unsuspecting people, if the criminals can beat the mailbox password) as remote dead drops for information which may be valuable in a criminal case. Voice mailboxes are located in the message system computer of the commercial vendor which supplies the voice-mail service, or they can be found on the computer at the location called. Voice mail messages can be written on magnetic disk or remain in the computer's memory, depending on the vendor's system. Of course, all networked systems, whether data or voice, may keep routine and disaster backups.
7. A. Routine BackupsMaking backups is a routine, mandatory discipline on multi-user systems. The system administrators will usually have written procedures which set out how often backup copies will be made and where they will be kept. Backups for large systems are often stored at remote locations. B. Disaster BackupsThese are additional backups of important data meant to survive all contingencies, such as fire, flood, etc. As extra protection, the data is stored off-site, usually in another building belonging to the business or in rented storage space. It would be unusual to find the disaster backups near the routine backups or original data. Again, these copies can be stored on diskettes, magnetic tape, or cartridge.