Security Solutions

A-17
Appendix A: Glossary
policy repository A data store such as a directory server, a flat file, or a database that contains
a network’s security policies. The PDP draws on the policies in the repository
to make its authentication decisions.
post-connect
testing
NAC tests that are run on endpoints after they have already connected success-
fully to the network. The network administrator configures the length of the
retest frequency. If a device has become infected or no longer complies with
an organization’s security policies, the NAC 800 quarantines it.
posture See integrity posture.
PPP Point-to-Point Protocol. A layer-2 protocol that connects a device such as a
personal computer to a server through a phone line. PPP uses a serial interface
and is sometimes considered part of the TCP/IP protocol suite. For more
information, see RFC 1661 at http://tools.ietf.org/html/rfc1661.
PPTP Point-to-Point Tunneling Protocol. A method originally devised by Cisco for
implementing VPNs. For more information, see RFC 2637 at http://
tools.ietf.org/html/rfc2637.
pre-connect
testing
Testing performed before an endpoint is granted access to the network. See
also post-connect testing.
pre-shared key See PSK.
private key One of a pair of keys that is generated from a single, large random number.
The private key is kept secret, not distributed, and is used to decrypt a message
that was encrypted using the public key. If used to encrypt a message, it “signs”
that message as originating from the private key’s owner.
PSK Pre-Shared Key. An alphanumeric character string agreed upon by two parties
in advance. In IKE negotiations, peers can exchange a pre-shared key that is
between 8 and 255 characters long to authenticate each other before opening
the IKE security association.
public key One of a pair of keys that is generated from a single, large random number.
The public key is distributed widely and is used to encrypt a message that can
be decrypted using only the private key. The public key also verifies data signed
by the private key.
public key
infrastructure
See PKI.