Saber LAN Workstation:-

A network management package from Saber Software Corporation that includes hardware and software inventory, server monitoring, client monitoring and control, traffic statistics, application metering, and software distribution. The package also includes several smaller but very useful features, including reporting functions, an automatic task scheduler, and print-queue management.

SAP:-

Abbreviation for Service Advertising Protocol. A protocol that provides a method for servers, printers, and other devices to advertise their services on a Novell NetWare network and allows routers to create and maintain a database of current internetwork server information. SAP packets are normally broadcast every 60 seconds.

SAS:-

Abbreviation for single-attached station. In the Fiber Distributed Data Interface (FDDI), a device attached to only one of the dual, counter-rotating rings. Non-critical devices, such as workstations, are often connected using SASs, because they are less expensive than DASs (dual-attached stations).

SATAN:-

Abbreviation for Security Administrator Tool for Analyzing Networks. A software package, available free over the Internet, that allows network administrators to identify gaps in their security systems. Critics of the program argue that SATAN less hackers exploit the information contained in the program on how to infiltrate these security systems, but so far, the program seems to have acted as a wake-up call for network administrators.

Script:-

A small program or macro invoked at a particular Lime. For example, a login script may execute the same specific set of instructions every Lime a user logs in to a network or computer system. A communications script may send the -identification information to an online information service each time a subscriber dials up the service.

SCSI:-

Acronym for Small Computer System Interface, pronounced "scuzzy". A high-speed parallel interface defined by the ANSI X3T9.2 committee. SCSI is used to connect -a computer to peripheral devices using just one port. Devices connected in this way are said to be "daisy-chained" together, and each device must have a unique identifier or priority number.

SCSI has been standard on the Macintosh since the Mac Plus was introduced, and it is' available on the IBM RS/6000, IBM PS/2 Model 65, and higher computers. It can also be installed in an IBM-compatible computer as a single expansion board, with a special 50-pin connector extending through the back of the computer case.

Today, SCSI is often used to connect hard disks, tape drives, CD-ROM drives, and other mass storage media, as well as scanners and printers. There are several SCSI interface definitions:

• SCSI-1: A 1986 definition of an 8-bit parallel interface with a maximum data transfer rate of 5 megabytes per second.

• SCSI-2 : This 1994 definition broadened the 8-bit data bus to 16- or 32-bits (also known as Fast SCSI). Wide SCSI and Fast SCSI can be combined to give Fast-Wide SCSI, with a 16-bit data bus and a maximum data-transfer rate of 20 megabytes per second. SCSI-2 is backward compatible with SCSI-1, but for maximum benefit, you should use SCSI-2 devices with a SCSI-2 controller.

• SCSI-2 : This definition increased the number of connected peripherals from seven to sixteen, increased cable lengths, added support for a serial interface and for a fiber optic interface. Data transfer rates depend on the hardware implementation; bit data rates in excess of 100 megabytes per second are possible.

SCSI terminator:-

The SCSI interface must be correctly terminated at both ends to prevent signals echoing on the bus. Many SCSI devices have built-in terminators that engage when they are needed. With some older SCSI devices, you must add an external SCSI terminator that plugs into the device's SCSI connector.

SDLC:-

Abbreviation for Synchronous Data Link Control. The data-link protocol most widely used in networks that conform to IBM's SNA (Systems Network Architecture). SDLC is a bit-oriented synchronous protocol that organizes information into well-defined units known as frames. SDLC is similar to the HDLC (High-level Data Link. Control) protocol defined by the International Standards Organization (ISO).

Security:-

Operating system controls used by the network administrator to limit users' access to approved areas. Security is usually implemented in the operating system at several levels: login and password security, account security, directory security, and file attributes security. Many personal computer operating systems do not provide much security.

If the computer system allows many users to dial in from remote locations over normal telephone lines, security should also extend to preventing unauthorized access via these lines. Data may also be encrypted by any of several methods, including the Data Encryption Standard (DES). When top secret data is processed on a network, diskless workstations are often used to minimize the opportunity for copying the data.

The United States Department of Defense Standard 5200.28 also known as the Orange Book, specifies the following security levels:

• Class D : A system that is not secure; most PC operating systems fall into this category.

• Class C1 : Requires an individual login, but allows group identification.

• Class C2 : Requires an individual level of login by password, with an audit mechanism. This level of security is found in Novell NetWare 4.x, Windows NT Server, and Banyan VINES network operating systems.

• Class B1 : Requires Department of Defense security clearance levels.

• Class B2 : Guarantees a path between the user and the security system and ensures that clearances cannot be changed.

• Class B3 : Security based on a mathematical model that must be viable and repeatable; the system must be managed by a network administrator in charge of security, and must remain secure when shut down.

• Class Al : The highest level of security, based on a mathematical model that can be proven. An operating system that lets anyone have complete access, such as DOS or the Macintosh System 7, falls into the D category.

CI and C2 levels can be implemented in a commercial environment. After the B1 level, the computing environment changes radically, and many of the mandatory access-control mechanisms become impractical for normal commercial operations.

Semaphore:-

An interprocess communication signal that indicates the status of a shared system resource, such as shared memory, in a multitasking operating system. There are several types of semaphore:

• Event semaphore: Allows a thread to tell other threads that an even has occurred and it is safe for them to resume execution.

• Mutual exclusion (mutex) semaphore: Protects system resources, such as files, data, and peripheral devices, from simultaneous access by several processes.

• Multiple wait (muxwait) semaphore: Allows threads to wait for multiple events to take place, or for multiple resources to become free.

Serial Communications: -

The transmission of information from computer to computer, or from computer to peripheral device, one bit at a time. Serial communications can be synchronous and controlled by a clock, or asynchronous and coordinated by start and stop bits embedded in the data stream. The sending and receiving devices must both use the same baud rate,   parity setting, and other communication parameters.

SERVER:-

A DOS program that boots the server and starts the NetWare operating system. After you bring down a server, use this command to start it up again.

Server:-

Any computer that makes access to files, printing, communications, and other services available to users of the network. In large networks, a dedicated server may run a special network operating system; in smaller installations, a non-dedicated server may run a personal computer operating system with peer-to-peer networking software running on top.

A server typically has a more advanced processor, more memory, a larger cache, and more disk storage than a single-user workstation; a server may also have several processors rather than just one. Many servers also have large power supplies, UPS (uninterruptible power supply) support, and fault-tolerance features, such as RAID (redundant array of inexpensive disks) technology.

Session Layer:-

The fifth of seven layers the ISO/ OS1 model for computer-to-computer communications. The session layer coordinates communications and maintains the session for as long as it is needed, performing security, logging, and administrative functions.

SGML:-

Abbreviation for Standard Generalized Markup Language. A standard (ISO 8879) for defining the structure and managing the contents of any digital document. HTML, used in many World Wide Web documents on the Internet, is a part of SGML.

Shadow Memory:-

In PCs based on the 80386 (or later) processor, the technique of copying the contents of the BIOS ROM (read only memory) into faster RAM (Random-access memory) when the computer first boots up; also known as shadow RAM or shadows ROM. RAM is usually two to three times faster than ROM, and the speedier access reduces the time required to execute a BIOS routine, so the processor spends more time working and less time waiting.

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