Fortinet FortiGate 4000 - Manual (Page 321)

Glossary
FortiGate-4000 Installation and Configuration Guide
321
SSH, Secure shell: A secure Telnet replacement that
you can use to log into another computer over a
network and run commands. SSH provides strong
secure authentication and secure communications
over insecure channels.
Subnet: A portion of a network that shares a common
address component. On TCP/IP networks, subnets are
defined as all devices whose IP addresses have the
same prefix. For example, all devices with IP
addresses that start with 100.100.100. would be part of
the same subnet. Dividing a network into subnets is
useful for both security and performance reasons.
IP networks are divided using a subnet mask.
Subnet Address: The part of the IP address that
identifies the subnetwork.
TCP, Transmission Control Protocol: One of the
main protocols in TCP/IP networks. TCP guarantees
delivery of data and also guarantees that packets will
be delivered in the same order in which they were sent.
UDP, User Datagram Protocol: A connectionless
protocol that, like TCP, runs on top of IP networks.
Unlike TCP, UDP provides very few error recovery
services, offering instead a direct way to send and
receive datagrams over an IP network. It is used
primarily for broadcasting messages over a network.
VPN, Virtual Private Network: A network that links
private networks over the Internet. VPNs use
encryption and other security mechanisms to ensure
that only authorized users can access the network and
that data cannot be intercepted.
Virus: A computer program that attaches itself to other
programs, spreading itself through computers or
networks by this mechanism usually with harmful
intent.
Worm: A program or algorithm that replicates itself
over a computer network, usually through email, and
performs malicious actions, such as using up the
computer's resources and possibly shutting the system
down.