Remote Access
 
Access to network resources not located on the same physical Ethernet. (Physical Ethernet here refers to an entire site network topology.)
 

Remote Control
 
Form of remote access where a device dialing in assumes control of another network node - all keystrokes on the remote are translated into keystrokes on the network node. Used primarily with IPX protocol.
 

Remote Node
 
Form of remote access where the device dialing in acts as a peer on the target network. Used with both IP and IPX protocols.
 

Repeater
 
A repeater is a network device that repeats signals from one cable onto one or more other cables, while restoring signal timing and waveforms.
 

Ring
 
A network topology in which the nodes are connected in a closed loop. Data is transmitted from node to node around the loop, always in the same direction.
 

RMON
 
SNMP-based standard for reporting various network conditions. RMON has 10 different management groups which provide detailed information about a network.
 

Rlogin
 
Rlogin is an application that provides a terminal interface between UNIX hosts using the TCP/IP network protocol. Unlike Telnet, Rlogin assumes the remote host is (or behaves like) a UNIX machine
 

ROM
 
Read-Only Memory, a memory device that retains its information even when power to it is removed. A ROM version of a network device does not need to download, since the ROM contains the entire executable code and thus never needs to reload it. Frequently the ROM is provided as "flash ROM", which can be reprogrammed by downloading if the user chooses. 

Rootkit
 
A rootkit is malware (malicious software) which consists of a program (or combination of several programs) designed to hide or obscure the fact that a system has been compromised. Contrary to what its name may imply, a rootkit does not grant a user administrator access as it requires such access to execute and tamper with system files and processes. An attacker may use a rootkit to replace vital system executables which may then be used to hide processes and files the attacker has installed along with the presence of the rootkit itself. Access to the hardware (e.g., the reset switch) is rarely required as a rootkit is intended to seize control of the operating system running on the hardware. Typically, rootkits act to obscure their presence on the system through subversion or evasion of standard operating system security mechanisms. Often, they are Trojans as well, thus fooling users into believing they are safe to run on their systems. Techniques used to accomplish this can include concealing running processes from monitoring programs, or hiding files or system data from the operating system. Rootkits may also install a 'backdoor' in a system by replacing the login mechanism (such as /bin/login) with an executable that accepts a secret login combination which in turn allows an attacker to access the system regardless of changes to the actual accounts on the system.
 

Router
 
Device capable of filtering/forwarding packets based upon data link layer information. Whereas a bridge or switch may only read MAC layer addresses to filter, routers are able to read data such as IP addresses and route accordingly.
 

RTEL
 
Lantronix' "reverse Telnet" software allows hosts using TCP/IP to establish a session with a device attached to a terminal server port.
 

Server
 
A computer that provides resources to be shared on the network, such as files (file server) or terminals (terminal server).
 

Session
 
A connection to a network service.
 

Shared Ethernet
 
Ethernet configuration in which a number of segments are bound together in a single collision domain. Hubs produce this type of configuration where only one node can transmit at a time.
 

SLIP
 
Serial Line Internet Protocol, a protocol for running TCP/IP over serial lines.
 

SNA
 
Systems Network Architecture. IBM's layered protocols for mainframe communications.
 

SNMP 
 
Simple Network Management Protocol, allows a TCP/IP host running an SNMP application to query other nodes for network-related statistics and error conditions. The other hosts, which provide SNMP agents, respond to these queries and allow a single host to gather network statistics from many other network nodes.
 

Source Code
 
Programs in an uncompiled or unassembled form.
 

Spanning Tree
 
An algorithm used by bridges to create a logical topology that connects all network segments, and ensures that only one path exists between any two stations.
 

Store and Forward
 
Technique for examining incoming packets on an Ethernet switch or bridge whereby the whole packet is read before forwarding or filtering takes place. Store and forward is a slightly slower process than cut-through, but it does ensure that all bad or misaligned packets are eliminated from the network by the switching device.
 

SPX
 
Sequential Packet exchange. Novell's implementation of SPP (Sequential Packet Protocol).
 

SQE
 
Ethernet-defined signal quality test function, frequently called "heartbeat."
 

Switch
 
Multiport Ethernet device designed to increase network performance by allowing only essential traffic on the attached individual Ethernet segments. Packets are filtered or forwarded based upon their source and destination addresses.
 

T-Connector
 
A T-shaped device with two female and one male BNC connectors.
 

TCP/IP
 
Transmission Control Protocol (TCP) and Internet Protocol (IP) are the standard network protocols in UNIX environments. They are almost always implemented and used together and called TCP/IP.
 

Telnet
 
Telnet is an application that provides a terminal interface between hosts using the TCP/IP network protocol. It has been standardized so that "telnetting" to any host should give one an interactive terminal session, regardless of the remote host type or operating system. Note that this is very different from the LAT software, which allows only local network access to LAT hosts only.
 

10BASE2
 
Ethernet running on thin coax network cable.
 

10BASE5
 
Ethernet running on Thickwire network cable.
 

10BASE-T
 
Ethernet running on unshielded twisted pair (UTP) cable. Note that 10BASE-T is a point-to-point network media, with one end of the cable typically going to a repeater/hub and the other to the network device.
 

Terminal Server
 
A concentrator that facilitates communication between hosts and terminals.
 

Terminator
 
Used on both ends of a standard Ethernet or Thinwire Ethernet segment, this special connector provides the 50 ohm termination resistance needed for the cable.

 
TFTP
 
Trivial File Transfer Protocol. On computers that run the TCP/IP networking software, TFTP is used to quickly send files across the network with fewer security features than FTP.
 

Thickwire
 
Half-inch diameter coax cable.
 

Thinwire 
 
Thin coaxial cable similar to that used for television/video hookups.
 

Throughput
 
The amount of data transmitted between two points in a given amount of time, e.g., 10 Mbps.
 

Token
 
The character sequence or frame, passed in sequence from node to node, to indicate that the node controlling it has the right to transmit for a given amount of time.
 

Token Ring
 
Developed by IBM, this 4 or 16 Mbps network uses a ring topology and a token-passing access method.
 

Topology
 
The arrangement of the nodes and connecting hardware that comprises the network. Types include ring, bus, star and tree. 

Tracking Cookies 
 
Tracking cookies are not viruses or malicious code. Cookies are only text files and therefore cannot be dangerous to your computer. 

The main purpose of cookies is to identify users and possibly prepare customized web pages for them. When you enter a web site using cookies, you may be asked to fill in a form providing such information as your name and interests. This information is sent to your web browser as a cookie file. The next time you go to the same web site, your browser will send the cookie to the web server. The server can use this information to present you with custom web pages. 

If you don’t want to use cookies you can check the settings of Internet Explorer browser to accept/deny the cookie file. 
 

Transceiver 
 
The actual device that interfaces between the network and the local node. The term generally refers to any connector, such as a MAU, that actively converts signals between the network and the local node. 
 

Transceiver Cable
 
Cable that attaches a device either to a standard or thin coax Ethernet segment. 

Trojan Horse
 
Trojan Horse is a malicious application, which can not spread itself. Original Trojan Horses were programs which acted as a useful utility. Although, in fact, their start used to cause damage to disc content (or part of it).

At the present time the most spreading Trojan Horses are BackDoor Trojans. They enable remote access to infected computers and PSW (Password Stealers) - they are trying to gather as much private information from the infected computer as possible and to send the info through the Internet.

To remove the Trojan Horse, it is enough to delete the detected file. 
 

Twisted-Pair Cable 
 
Inexpensive, multiple-conductor cable comprised of one or more pairs of 18 to 24 gauge copper strands. The strands are twisted to improve protection against electromagnetic and radio frequency interference. The cable, which may be either shielded or unshielded, is used in low-speed communications, as telephone cable. It is used only in baseband networks because of its narrow bandwidth.