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Glossary
GL-16
Cisco ASA 5500 Series Configuration Guide using ASDM
Q
QoS
quality of service. Measure of performance for a transmission system that reflects its transmission
quality and service availability.
R
RA
Registration Authority. An authorized proxy for a CA. RAs can perform certificate enrollment and can
issue CRLs. See also CA, certificate, public key.
RADIUS
Remote Authentication Dial-In User Service. RADIUS is a distributed client/server system that
secures networks against unauthorized access. RFC 2058 and RFC 2059 define the RADIUS protocol
standard. See also AAA and TACACS+.
refresh
Retrieve the running configuration from the ASA and update the screen. The icon and the button
perform the same function.
registration
authority
See RA.
replay-detection
A security service where the receiver can reject old or duplicate packets to defeat replay attacks.
Replay attacks rely on the attacker sending out older or duplicate packets to the receiver and the
receiver thinking that the bogus traffic is legitimate. Replay-detection is done by using sequence
numbers combined with authentication and is a standard feature of IPsec.
RFC
Request for Comments. RFC documents define protocols and standards for communications over the
Internet. RFCs are developed and published by IETF.
RIP
Routing Information Protocol. Interior Gateway Protocol (IGP) supplied with UNIX BSD systems.
The most common IGP in the Internet. RIP uses hop count as a routing metric.
RLLA
Reserved Link Local Address. Multicast addresses range from 224.0.0.0 to 239.255.255.255; however
only the range 224.0.1.0 to 239.255.255.255 is available to users. The first part of the multicast
address range, 224.0.0.0 to 224.0.0.255, is reserved and referred to as the RLLA. These addresses are
unavailable.
route, routing
The path through a network.
routed firewall
mode
In routed firewall mode, the ASA is counted as a router hop in the network. It performs NAT between
connected networks and can use OSPF or RIP. See also transparent firewall mode.
RPC
Remote Procedure Call. RPCs are procedure calls that are built or specified by clients and executed
on servers, with the results returned over the network to the clients.
RSA
A public key cryptographic algorithm (named after its inventors, Rivest, Shamir, and Adelman) with
a variable key length. The main weakness of RSA is that it is significantly slow to compute compared
to popular secret-key algorithms, such as DES. The Cisco implementation of IKE uses a
Diffie-Hellman exchange to get the secret keys. This exchange can be authenticated with RSA (or
preshared keys). With the Diffie-Hellman exchange, the DES key never crosses the network (not even
in encrypted form), which is not the case with the RSA encrypt and sign technique. RSA is not public
domain, and must be licensed from RSA Data Security.