Cisco ASA 5505 - Manual (Page 1956)

Glossary
GL-18
Cisco ASA 5500 Series Configuration Guide using the CLI
security context You can partition a single ASA into multiple virtual firewalls, known as security contexts. Each
context is an independent firewall, with its own security policy, interfaces, and administrators.
Multiple contexts are similar to having multiple stand-alone firewalls.
security services See cryptography .
serial transmission A method of data transmission in which the bits of a data character are transmitted sequentially over
a single channel.
SGCP Simple Gateway Control Protocol. Controls VoIP gateways by an external call control element (called
a call-agent).
SGSN Serving GPRS Support Node. The SGSN ensures mobility management, session management, and
packet relaying functions.
SHA-1 Secure Hash Algorithm 1. SHA-1 [NIS94c] is a revision to SHA that was published in 1994. SHA is
closely modeled after MD4 and produces a 160-bit digest. Because SHA produces a 160-bit digest, it
is more resistant to brute-force attacks than 128-bit hashes (such as
MD5 ), but it is slower. Secure
Hash Algorithm 1 is a joint creation of the National Institute of Standards and Technology and the
National Security Agency. This algorithm, like other hash algorithms, is used to generate a hash value,
also known as a message digest, that acts like a
CRC used in lower-layer protocols to ensure that
message contents are not changed during transmission. SHA-1 is generally considered more secure
than
MD5 .
SIP Session Initiation Protocol. Enables call handling sessions, particularly two-party audio conferences,
or calls. SIP works with
SDP for call signaling. SDP specifies the ports for the media stream. Using
SIP, the ASA can support any SIP VoIP gateways and VoIP proxy servers.
site-to-site VPN A site-to-site VPN is established between two IPsec peers that connect remote networks into a single
VPN . In this type of VPN , neither IPsec peer is the destination nor source of user traffic. Instead, each
IPsec peer provides encryption and authentication services for hosts on the LAN s connected to each
IPsec peer. The hosts on each LAN send and receive data through the secure tunnel established by the
pair of IPsec peers.
SKEME A key exchange protocol that defines how to derive authenticated keying material, with rapid key
refreshment.
SMR Stub Multicast Routing. SMR allows the ASA to function as a stub router. A stub router is a device
that acts as an
IGMP proxy agent. IGMP is used to dynamically register specific hosts in a multicast
group on a particular LAN with a multicast router. Multicast routers route multicast data transmissions
to hosts that are registered to receive specific multimedia or other broadcasts. A stub router forwards
IGMP messages between hosts and MC router s.
SMTP Simple Mail Transfer Protocol. SMTP is an Internet protocol that supports email services.
SNMP Simple Network Management Protocol. A standard method for managing network devices using data
structures called Management Information Bases.
split tunneling Allows a remote VPN client simultaneous encrypted access to a private network and clear unencrypted
access to the Internet . If you do not enable split tunneling, all traffic between the VPN client and the
ASA is sent through an IPsec tunnel. All traffic originating from the VPN client is sent to the outside
interface through a tunnel, and client access to the Internet from its remote site is denied.