Glossary
GL-15
Cisco ASA 5500 Series Configuration Guide using ASDM
OL-20339-01
PPPoE
Point-to-Point Protocol over Ethernet. An IP protocol that encapsulates PPP packets and sends them 
over a local network or the internet to establish a connection to a host, usually between a client and 
an ISP.
PPTP
Point-to-Point Tunneling Protocol. PPTP was introduced by Microsoft to provide secure remote 
access to Windows networks; however, because it is vulnerable to attack, PPTP is commonly used 
only when stronger security methods are not available or are not required. PPTP Ports are pptp, 
1723/tcp, 1723/udp, and pptp. For more information about PPTP, see RFC 2637. See also PAC, PPTP 
GRE, PPTP GRE tunnel, PNS, PPTP session, and PPTP TCP.
PPTP GRE
Version 1 of GRE for encapsulating PPP traffic.
PPTP GRE tunnel
A tunnel defined by a PNS-PAC pair. The tunnel protocol is defined by a modified version of GRE. 
The tunnel carries PPP datagrams between the PAC and the PNS. Many sessions are multiplexed on a 
single tunnel. A control connection operating over TCP controls the establishment, release, and 
maintenance of sessions and of the tunnel itself.
PPTP session
PPTP is connection-oriented. The PNS and PAC  maintain the state for each user that is attached to a 
PAC. A session is created when an end-to-end PPP connection is attempted between a dial-up user and 
the PNS. The datagrams related to a session are sent over the tunnel between the PAC and PNS.
PPTP TCP
Standard TCP session over which PPTP call control and management information is passed. The 
control session is logically associated with, but separate from, the sessions being tunneled through a 
PPTP tunnel.
preshared key
A preshared key provides a method of IKE authentication that is suitable for networks with a limited, 
static number of IPsec peers. This method is limited in scalability because the key must be configured 
for each pair of IPsec peers. When a new IPsec peer is added to the network, the preshared key must 
be configured for every IPsec peer with which it communicates. Using certificates and CAs provides 
a more scalable method of IKE authentication.
primary, primary 
unit
The adaptive security appliance normally operating when two units, a primary and secondary, are 
operating in failover mode.
privileged EXEC 
mode
The highest privilege level at the ASA CLI. Any user EXEC mode command will work in privileged 
EXEC mode. The privileged EXEC mode prompt appears as follows after you enter the enable 
command:
hostname> enable
hostname#
See also command-specific configuration mode, global configuration mode, user EXEC mode.
protocol, protocol 
literals
A standard that defines the exchange of packets between network nodes for communication. Protocols 
work together in layers. Protocols are specified in the adaptive security appliance configuration as part 
of defining a security policy by their literal values or port numbers. Possible adaptive security 
appliance protocol literal values are ahp, eigrp, esp, gre, icmp, igmp, igrp, ip, ipinip, ipsec, nos, ospf, 
pcp, snp, tcp, and udp.