Glossary
GL-18
Cisco Intrusion Prevention System Sensor CLI Configuration Guide for IPS 5.0
78-16527-01
UDP
User Datagram Protocol. Connectionless transport layer protocol in the TCP/IP protocol stack. UDP is
a simple protocol that exchanges datagrams without acknowledgments or guaranteed delivery,
requiring that error processing and retransmission be handled by other protocols. UDP is defined in
RFC 768.
unblock
To direct a router to remove a previously applied block.
UPS
Uninterruptable Power Source.
UTC
Coordinated Universal Time. Time zone at zero degrees longitude. Formerly called Greenwich Mean
Time (GMT) and Zulu time.
V
VACL
VLAN ACL. An ACL that filters all packets (both within a VLAN and between VLANs) that pass
through a switch. Also known as security ACLs.
VID
Version identifier. Part of the UDI.
virtual sensor
A logical grouping of sensing interfaces and the configuration policy for the signature engines and
alarm filters to apply to them. In other words, multiple virtual sensors running on the same appliance,
each configured with different signature behavior and traffic feeds. IPS 5.x supports only one virtual
sensor.
virus
Hidden, self-replicating section of computer software, usually malicious logic, that propagates by
infecting—that is, inserting a copy of itself into and becoming part of—another program. A virus
cannot run by itself; it requires that its host program be run to make the virus active.
virus update
A signature update specifically addressing viruses.
VLAN
Virtual Local Area Network. Group of devices on one or more LANs that are configured (using
management software) so that they can communicate as if they were attached to the same wire, when
in fact they are located on a number of different LAN segments. Because VLANs are based on logical
instead of physical connections, they are extremely flexible.
VMS
CiscoWorks VPN/Security Management Solution. A suite of network security applications that
combines web-based tools for configuring, monitoring, and troubleshooting enterprise VPN, firewalls,
network intrusion detection systems and host-based intrusion prevention systems.
VoIP
Voice over IP. The capability to carry normal telephony-style voice over an IP-based internet with
POTS-like functionality, reliability, and voice quality. VoIP enables a router to carry voice traffic (for
example, telephone calls and faxes) over an IP network. In VoIP, the DSP segments the voice signal into
frames, which then are coupled in groups of two and stored in voice packets. These voice packets are
transported using IP in compliance with ITU-T specification H.323.
VPN
Virtual Private Network(ing). Enables IP traffic to travel securely over a public TCP/IP network by
encrypting all traffic from one network to another. A VPN uses “tunneling” to encrypt all information
at the IP level.
vulnerability
One or more attributes of a computer or a network that permit a subject to initiate patterns of misuse
on that computer or network.
