User Guide

Getting Started 39
Glossary
A TCP-based service that supports remote logins (usually to UNIX systems).
With telnet, you are sending your username and password over a network and
they may be stolen by someone and used to break in. Consider a VPN for
privacy.
tftp
Trivial file transfer protocol, a UDP-based file transfer protocol. tftp is a
security risk because it involves no interaction with the user - it can occur
without you knowing about it.
Toggle
A setting that switches between two positions or values.
trojan
A program or piece of executable code that is transmitted without the user’s
knowledge, often allowing outsiders to break into or control the system
Tunnel
Encapsulates one protocol or data stream within another. A Virtual Private
Network (VPN) tunnels data by encrypting it and then encapsulating it within
a protocol such as TCP (better) or UDP (worse).
UDP
A connectionless (datagram) Internet Protocol carried in IP packets. Examples
of services and applications that use UDP are ICQ, DNS, NetBIOS (for
broadcasts etc.) and RIP.
Virus (software)
A piece of code that works without the knowledge of the recipient. It is
transmitted inside other software, can duplicate itself, spread and damage
your data and/or system.
VPN
Virtual Private Network. A secure private connection, usually through an
untrusted network. You can link the LAN’s of two offices through the Internet
using a VPN, and systems in either office can access those in the other, as if
they were on the same LAN. The route through the Internet is invisible.
Hackers or snoopers on the Internet just see encrypted traffic and cannot get
your private information.