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Certpedia: Terms That Start With T

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  • TACACS+ (Terminal Access Controller Access-Control System) - TACACS+ is a proprietary Cisco security application that provides centralized validation of users attempting to gain access to a router or network access server. The TACACS+ protocol provides authentication between the network access server and the TACACS+ daemon, and it ensures confidentiality because all protocol exchanges between a network access server and a TACACS+ daemon are encrypted. Whereas RADIUS combines authentication and authorization in a user profile, TACACS+ separates the two operations. Another difference is that TACACS+ uses the Transmission Control Protocol (TCP) while RADIUS uses the User Datagram Protocol (UDP).

  • TCP (Transmission Control Protocol) - TCP is a transport layer protocol used in conjunction with the Internet Protocol (IP). TCP allows applications to create connections with one another and stream data. TCP breaks data into manageable packets and tracks information such as source and destination of packets. It is able to reroute packets and is responsible for guaranteed delivery of the data. More information...

  • Telnet - Telnet is a protocol that allows you to connect to remote computers over the Internet. There is a telnet server on the remote host, which the telnet client negotiates with to establish a connection. Once connected, the client becomes a virtual terminal, and allows you to interface with the host computer via command line from your computer. In most cases, you'll be asked to log into the remote system. This usually requires an account on that host. Telnet uses port 23. Because of security issues with Telnet, Secure Shell (SSH) is replacing becoming the new standard.

  • TFTP (Trivial File Transfer Protocol) - TFTP is a "Lite" version of FTP and can be used for basic file transfer operations. It uses the User Datagram Protocol (UDP) and provides no security features. It is most often used by servers to boot diskless workstations, X-terminals, and routers.

  • TIFF (Tagged Image File Format) - Developed by Aldus for use with PostScript printing, TIFF files are uncompressed bitmap images commonly used in desktop publishing, faxing, 3-D applications, and medical imaging applications. A plug-in is required to view TIFF images in a browser. TIFF images typically use the .tif file extension.

  • TLS - Transport Layer Security is a cryptographic protocol that provides security for communications over networks such as the Internet. TLS and SSL encrypt the segments of network connections at the Transport Layer end-to-end. Several versions of the protocols are in wide-spread use in applications like web browsing, electronic mail, Internet faxing, instant messaging and voice-over-IP (VoIP).

  • Token Ring - Token Ring is an older standard that isn't very widely used anymore as most have migrated to some form of Ethernet or other advanced technology. Ring topologies can have transmission rates of either 4 or 16mbps. Token passing is the access method used by token ring networks, whereby, a 3bit packet called a token is passed around the network. A computer that wishes to transmit must wait until it can take control of the token, allowing only one computer to transmit at a time. This method of communication aims to prevent collisions. Token Ring networks use multistation access units (MSAUs) instead of hubs on an Ethernet network.
    Token Ring/IEEE 802.5

  • Traceroute - A command-line troubleshooting tool that enables you to view the route to a specified host. This will show how many hops the packets have to travel and how long it takes. In Windows operating systems, the command used is "tracert".


  • Traffic Shaping (also known as "packet shaping" or ITMPs: Internet Traffic Management Practices) is the control of computer network traffic in order to optimize or guarantee performance, increase/decrease latency, and/or increase usable bandwidth by delaying packets that meet certain criteria. More specifically, traffic shaping is any action on a set of packets (often called a stream or a flow) which imposes additional delay on those packets such that they conform to some predetermined constraint (a contract or traffic profile).Traffic shaping provides a means to control the volume of traffic being sent into a network in a specified period (bandwidth throttling), or the maximum rate at which the traffic is sent (rate limiting), or more complex criteria such as GCRA. This control can be accomplished in many ways and for many reasons; however traffic shaping is always achieved by delaying packets. Traffic shaping is commonly applied at the network edges to control traffic entering the network, but can also be applied by the traffic source (for example, computer or network card - cite_note-2) or by an element in the network. Traffic policing is the distinct but related practice of packet dropping and packet marking.

  • Trojan Horse - A Trojan is a type of file that appears to do one thing, but in reality does another. A Trojan can be a file that operates in an expected way, but also has a secret operation that subverts security. Once a Trojan is installed, it can perform a wide variety of destructive tasks and/or provide secure information to the attacker.

  • Trunking - VLANs are local to each switch's database, and VLAN information is not passed between switches. Trunk links provide VLAN identification for frames traveling between switches. The VLAN trunking protocol (VTP) is the protocol that switches use to communicate among themselves about VLAN configuration.