Cisco ROUTER-SDM-CD User Manual page 976

Glossary
PPPoA
PPPoE
PPTP
pre-shared key
private key
pseudo random
Cisco Router and Security Device Manager 2.5 User's Guide
GL-28
Point-to-Point Protocol over Asynchronous Transfer Mode (ATM). Primarily
implemented as part of ADSL, PPPoA relies on RFC1483, operating in either
Logical Link Control-Subnetwork Access Protocol (LLC-SNAP) or VC-Mux
mode.
Point-to-Point Protocol over Ethernet. PPP encapsulated in Ethernet frames.
PPPoE enables hosts on an Ethernet network to connect to remote hosts through
a broadband modem.
Point-to-Point Tunneling Protocol. Creates client-initiated tunnels by
encapsulating packets into IP datagrams for transmission over TCP/IP-based
networks. Can be used as an alternative to the L2F and L2TP tunneling
protocols. Proprietary Microsoft protocol.
One of three authentication methods offered in IPSec, with the other two
methods being RSA encrypted nonces, and RSA signatures. Pre-shared keys
allow for one or more clients to use individual shared secrets to authenticate
encrypted tunnels to a gateway using IKE. Pre-shared keys are commonly used
in small networks of up to 10 clients. With pre-shared keys, there is no need to
involve a CA for security.
The Diffie-Hellman key exchange combines public and private keys to create a
shared secret to be used for authentication between IPSec peers. The shared
secret can be shared between two or more peers. At each participating peer, you
would specify a shared secret as part of an IKE policy. Distribution of this
pre-shared key usually takes place through a secure out-of-band channel. When
using a pre-shared key, if one of the participating peers is not configured with
the same pre-shared key, the IKE SA cannot be established. An IKE SA is a
prerequisite to an IPSec SA. You must configure the pre-shared key at all peers.
Digital certification and wildcard pre-shared keys (which allow for one or more
clients to use a shared secret to authenticate encrypted tunnels to a gateway) are
alternatives to pre-shared keys. Both digital certification and wildcard
pre-shared keys are more scalable than pre-shared keys.
See public key encryption.
An ordered sequence of bits that appears superficially similar to a truly random
sequence of the same bits. A key generated from a pseudo random number is
called a nonce.
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