Cisco ASA 5505 - Manual (Page 1946)

Glossary
GL-8
Cisco ASA 5500 Series Configuration Guide using the CLI
H.323 Allows dissimilar communication devices to communicate with each other by using a standardized
communication protocol. H.323 defines a common set of CODECs, call setup and negotiating
procedures, and basic data transport methods.
H.323 RAS Registration, admission, and status signaling protocol. Enables devices to perform registration,
admissions, bandwidth changes, and status and disengage procedures between
VoIP gateway and the
gatekeeper.
H.450.2 Call transfer supplementary service for H.323 .
H.450.3 Call diversion supplementary service for H.323 .
Hash, Hash
Algorithm A hash algorithm is a one-way function that operates on a message of arbitrary length to create a
fixed-length message digest used by cryptographic services to ensure its data integrity. MD5 has a
smaller digest and is considered to be slightly faster than
SHA-1 . Cisco uses both SHA-1 and MD5
hashes within our implementation of the IPsec framework. See also encryption , HMAC , and VPN .
headend A firewall, concentrator, or other host that serves as the entry point into a private network for VPN
client connections over the public network. See also ISP and VPN .
HMAC A mechanism for message authentication using cryptographic hashes such as SHA-1 and MD5 .
host The name for any device on a TCP/IP network that has an IP address. See also network and node .
host/network An IP address and netmask used with other information to identify a single host or network subnet for
ASA configuration, such as an address translation (
xlate ) or ACE .
HTTP Hypertext Transfer Protocol. A protocol used by browsers and web servers to transfer files. When a
user views a web page, the browser can use HTTP to request and receive the files used by the web
page. HTTP transmissions are not encrypted.
HTTPS Hypertext Transfer Protocol Secure. An SSL -encrypted version of HTTP.
I
IANA Internet Assigned Number Authority. Assigns all port and protocol numbers for use on the Internet .
ICMP Internet Control Message Protocol. Network-layer Internet protocol that reports errors and provides
other information relevant to IP packet processing.
IDS Intrusion Detection System. A method of detecting malicious network activity by signatures and then
implementing a policy for that signature.
IETF The Internet Engineering Task Force. A technical standards organization that develops RFC
documents defining protocols for the Internet .
IGMP Internet Group Management Protocol. IGMP is a protocol used by IPv4 systems to report IP multicast
memberships to neighboring multicast routers.