Cisco ASA 5505 - Manual (Page 1949)

Glossary
GL-11
Cisco ASA 5500 Series Configuration Guide using the CLI
K
key A data object used for encryption , decryption , or authentication .
L
L2TP Layer Two Tunneling Protocol. An IETF standards track protocol defined in RFC 2661 that provides
tunneling of PPP. L2TP is an extension to the PPP. L2TP merges the older Cisco Layer Two
Forwarding (L2F) protocol with PPTP. L2TP can be used with IPsec encryption and is considered
more secure against attack than PPTP.
LAN Local area network. A network residing in one location, such as a single building or campus. See also
Internet , intranet , and network .
layer, layers Networking models implement layers with which different protocols are associated. The most
common networking model is the OSI model, which consists of the following seven layers, in order:
physical, data link, network, transport, session, presentation, and application.
LCN Logical channel number.
LDAP Lightweight Directory Access Protocol. LDAP provides management and browser applications with
access to X.500 directories.
M
mask A 32-bit mask that shows how an Internet address is divided into network, subnet, and host parts. The
mask has ones in the bit positions to be used for the network and subnet parts, and zeros for the host
part. The mask should contain at least the standard network portion, and the subnet field should be
contiguous with the network portion.
MCR See multicast .
MC router Multicast (MC) routers route multicast data transmissions to the hosts on each LAN in an internetwork
that are registered to receive specific multimedia or other broadcasts. See also
multicast .
MD5 Message Digest 5. A one-way hashing algorithm that produces a 128-bit hash. Both MD5 and SHA-1
are variations on MD4 and are designed to strengthen the security of the MD4 hashing algorithm.
SHA-1 is more secure than MD4 and MD5. Cisco uses hashes for authentication within the IPsec
framework. Also used for message authentication in SNMP v.2. MD5 verifies the integrity of the
communication, authenticates the origin, and checks for timeliness.
MD5 has a smaller digest and is
considered to be slightly faster than SHA-1 .
MDI media dependent interface.
MDIX media dependent interface crossover.
message digest A message digest is created by a hash algorithm, such as MD5 or SHA-1 , that is used for ensuring
message integrity.