ZyXEL Communications ZyWALL 10 User Manual page 247

Proxy Server A server that performs network operations in lieu of other systems on the network.
Proxy Servers are most often used as part of a firewall to mask the identity of users
inside a corporate network yet still provide access to the Internet. When a user connects
to a proxy server, via a web browser or other networked application, he submits
commands to the proxy server. The server then submits those same commands to the
Internet, yet without revealing any information about the system that originally requested
the information. Proxy servers are an ideal way to also have all users on a corporate
network channel through one point for all external communications. Proxy servers can
be configured to block certain kinds of connections and stop some hacks.
PSTN
Public Switched Telephone Network was put into place many years ago as a voice
telephone call-switching system. The system transmits voice calls as analog signals
across copper twisted cables from homes and businesses to neighborhood COs (central
offices); this is often called the local loop. The PSTN is a circuit-switched system,
meaning that an end-to-end private circuit is established between caller and callee.
Public Key System of encrypting electronic files using a key pair. The key pair contains a public key
Encryption used during encryption, and a corresponding private key used during decryption.
PVC
Permanent Virtual Circuit. A PVC is a logical point-to-point circuit between customer
sites. PVCs are low-delay circuits because routing decisions do not need to be made
along the way. Permanent means that the circuit is preprogrammed by the carrier as a
path through the network. It does not need to be set up or torn down for each session.
Reconnaissance The finding and observation of potential targets for a cracker to attack.
RFC
An RFC (Request for Comments) is an Internet formal document or standard that is the
result of committee drafting and subsequent review by interested parties. Some RFCs
are informational in nature. Of those that are intended to become Internet standards, the
final version of the RFC becomes the standard and no further comments or changes are
permitted. Change can occur, however, through subsequent RFCs.
RIP
Routing Information Protocol is an interior or intra-domain routing protocol that uses the
distance-vector routing algorithms. RIP is used on the Internet and is common in the
NetWare environment as a method for exchanging routing information between routers.
Router A device that connects two networks together. Routers monitor, direct, and filter
information that passes between these networks. Because of their location, routers are
a good place to install traffic or mail filters. Routers are also prone to attacks because
they contain a great deal of information about a network.
SAP
In NetWare, the SAP (Service Advertising Protocol) broadcasts information about
available services on the network that other network devices can listen to. A server
sends out SAP messages every 60 seconds. A server also sends out SAP messages to
inform other devices that it is closing down. Workstations use SAP to find services they
need on the network.
SATAN A UNIX program that gathers information on networks and stores it in databases. It is
helpful in finding security flaws such as incorrect settings, software bugs and poor policy
decisions. It shows network services that are running, the different types of hardware
and software on the network, and other information. It was written to help users find
Glossary
ZyWALL 10 Internet Security Gateway
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