Cisco Cisco ASA Series User manual

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Cisco ASA Series CLI Configuration Guide
Software Version 9.0 for the ASA 5505, ASA 5510, ASA 5520, ASA 5540, ASA 5550,
ASA 5512-X, ASA 5515-X, ASA 5525-X, ASA 5545-X, ASA 5555-X, ASA 5580, ASA
5585-X, and the ASA Services Module
Released: October 29, 2012
Updated: February 25, 2013
Text Part Number: N/A, Online only

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Cisco ASA Series CLI Configuration Guide
Copyright © 2012-2013 Cisco Systems, Inc. All rights reserved.

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Cisco ASA Series CLI Configuration Guide
About This Guide
This preface introduces Cisco ASA Series CLI Configuration Guide and includes the following sections:
•Document Objectives, page 1
•Audience, page 1
•Related Documentation, page 1
•Conventions, page 2
•Obtaining Documentation and Submitting a Service Request, page 2
Document Objectives
The purpose of this guide is to help you configure the ASA using the command-line interface. This guide
does not cover every feature, but describes only the most common configuration scenarios.
You can also configure and monitor the ASA by using ASDM, a web-based GUI application. ASDM
includes configuration wizards to guide you through some common configuration scenarios, and online
help for less common scenarios.
This guide applies to the Cisco ASA series. Throughout this guide, the term “ASA” applies generically
to supported models, unless specified otherwise.
Audience
This guide is for network managers who perform any of the following tasks:
•Manage network security
•Install and configure firewalls/ASAs
•Configure VPNs
•Configure intrusion detection software
Related Documentation
For more information, see Navigating the Cisco ASA Series Documentation at
http://www.cisco.com/en/US/docs/security/asa/roadmap/asaroadmap.html.

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Conventions
This document uses the following conventions:
Note Means reader take note.
Tip Means the following information will help you solve a problem.
Caution Means reader be careful. In this situation, you might perform an action that could result in equipment
damage or loss of data.
Obtaining Documentation and Submitting a Service Request
For information on obtaining documentation, using the Cisco Bug Search Tool (BST), submitting a
service request, and gathering additional information, see What’s New in Cisco Product Documentation
at: http://www.cisco.com/c/en/us/td/docs/general/whatsnew/whatsnew.html.
Subscribe to What’s New in Cisco Product Documentation, which lists all new and revised
Cisco technical documentation, as an RSS feed and deliver content directly to your desktop using a
reader application. The RSS feeds are a free service.
Convention Indication
bold font Commands and keywords and user-entered text appear in bold font.
italic font Document titles, new or emphasized terms, and arguments for which you supply
values are in italic font.
[ ] Elements in square brackets are optional.
{x | y | z } Required alternative keywords are grouped in braces and separated by
vertical bars.
[ x | y | z ] Optional alternative keywords are grouped in brackets and separated by
vertical bars.
string A nonquoted set of characters. Do not use quotation marks around the string or
the string will include the quotation marks.
courier font Terminal sessions and information the system displays appear in courier font.
courier bold font Commands and keywords and user-entered text appear in bold courier font.
courier italic font Arguments for which you supply values are in courier italic font.
< > Nonprinting characters such as passwords are in angle brackets.
[ ] Default responses to system prompts are in square brackets.
!, # An exclamation point (!) or a pound sign (#) at the beginning of a line of code
indicates a comment line.

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GLOSSARY
Numerics | A| B| C| D| E| F| G| H| I| J| K| L| M| N| O| P| Q| R| S| T| U| V| W| X
Numerics
3DES See DES.
A
AAA Authentication, authorization, and accounting. See also TACACS+ and RADIUS.
ABR Area Border Router. In OSPF, a router with interfaces in multiple areas.
ACE access control entry. Information entered into the configuration that lets you specify what type of traffic
to permit or deny on an interface. By default, traffic that is not explicitly permitted is denied.
Access Modes The ASA CLI uses several command modes. The commands available in each mode vary. See also user
EXEC mode, privileged EXEC mode, global configuration mode, command-specific configuration mode.
ACL access control list. A collection of ACEs. An ACL lets you specify what type of traffic to allow on an
interface. By default, traffic that is not explicitly permitted is denied. ACLs are usually applied to the
interface which is the source of inbound traffic. See also rule, outbound ACL.
ActiveX A set of object-oriented programming technologies and tools used to create mobile or portable
programs. An ActiveX program is roughly equivalent to a Java applet.
Address Resolution
Protocol
See ARP.
address translation The translation of a network address and/or port to another network address/or port. See also IP address,
interface PAT, NAT, PAT, Static PAT, xlate.
AES Advanced Encryption Standard. A symmetric block cipher that can encrypt and decrypt information.
The AES algorithm is capable of using cryptographic keys of 128, 192 and 256 bits to encrypt and
decrypt data in blocks of 128 bits. See also DES.
AH Authentication Header. An IP protocol (type 51) that can ensure data integrity, authentication, and
replay detection. AH is embedded in the data to be protected (a full IP datagram, for example). AH can
be used either by itself or with ESP. AH is an older IPsec protocol that is less important in most
networks than ESP. AH provides authentication services but does not provide encryption services. It is
provided to ensure compatibility with IPsec peers that do not support ESP, which provides both
authentication and encryption. See also encryption and VPN. Refer to the RFC 2402.
AIP Advanced Inspection and Prevention. For example, the AIP SSM or AIP SSC, which runs IPS software.

Glossary
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A record address “A” stands for address, and refers to name-to-address mapped records in DNS.
APCF Application Profile Customization Framework. Lets the security appliance handle nonstandard
applications so that they render correctly over a clientless SSL VPN connection.
ARP Address Resolution Protocol. A low-level TCP/IP protocol that maps a hardware address, or MAC
address, to an IP address. An example hardware address is 00:00:a6:00:01:ba. The first three groups of
characters (00:00:a6) identify the manufacturer; the rest of the characters (00:01:ba) identify the
system card. ARP is defined in RFC 826.
ASA Adaptive Security Algorithm. Used by the ASA to perform inspections. ASA allows one-way (inside
to outside) connections without an explicit configuration for each internal system and application. See
also inspection engine.
ASA adaptive ASA.
ASDM Adaptive Security Device Manager. An application for managing and configuring a single ASA.
asymmetric
encryption
Also called public key systems, asymmetric encryption allows anyone to obtain access to the public
key of anyone else. Once the public key is accessed, you can send an encrypted message to that person
using the public key. See also encryption, public key.
authentication Cryptographic protocols and services that verify the identity of users and the integrity of data. One of
the functions of the IPsec framework. Authentication establishes the integrity of the datastream and
ensures that it is not tampered with in transit. It also provides confirmation about the origin of the
datastream. See also AAA, encryption, and VPN.
Auto Applet
Download
Automatically downloads the clientless SSL VPN port-forwarding applet when the user first logs in to
clientless SSL VPN.
auto-signon This command provides a single sign-on method for clientless SSL VPN users. It passes the clientless
SSL VPN login credentials (username and password) to internal servers for authentication using
NTLM authentication, basic authentication, or both.
B
backup server IPsec backup servers let a VPN client connect to the central site when the primary security appliance
is unavailable.
BGP Border Gateway Protocol. BGP performs interdomain routing in TCP/IP networks. BGP is an Exterior
Gateway Protocol, which means that it performs routing between multiple autonomous systems or
domains and exchanges routing and access information with other BGP systems. The ASA does not
support BGP. See also EGP.
BLT stream Bandwidth Limited Traffic stream. Stream or flow of packets whose bandwidth is constrained.
BOOTP Bootstrap Protocol. Lets diskless workstations boot over the network as is described in RFC 951 and
RFC 1542.
BPDU Bridge Protocol Data Unit. Spanning-Tree Protocol hello packet that is sent out at configurable
intervals to exchange information among bridges in the network. Protocol data unit is the OSI term for
packet.

Glossary
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C
CA Certificate Authority, Certification Authority. A third-party entity that is responsible for issuing and
revoking certificates. Each device with the public key of the CA can authenticate a device that has a
certificate issued by the CA. The term CA also refers to software that provides CA services. See also
certificate, CRL, public key, RA.
cache A temporary repository of information accumulated from previous task executions that can be reused,
decreasing the time required to perform the tasks. Caching stores frequently reused objects in the system
cache, which reduces the need to perform repeated rewriting and compressing of content.
CBC Cipher Block Chaining. A cryptographic technique that increases the encryption strength of an
algorithm. CBC requires an initialization vector (IV) to start encryption. The IV is explicitly given in
the IPsec packet.
certificate A signed cryptographic object that contains the identity of a user or device and the public key of the
CA that issued the certificate. Certificates have an expiration date and may also be placed on a CRL if
known to be compromised. Certificates also establish non-repudiation for IKE negotiation, which
means that you can prove to a third party that IKE negotiation was completed with a specific peer.
CHAP Challenge Handshake Authentication Protocol.
CIFS Common Internet File System. It is a platform-independent file sharing system that provides users with
network access to files, printers, and other machine resources. Microsoft implemented CIFS for
networks of Windows computers, however, open source implementations of CIFS provide file access
to servers running other operating systems, such as Linux, UNIX, and Mac OS X.
Citrix An application that virtualizes client-server applications and optimizes web applications.
CLI command-line interface. The primary interface for entering configuration and monitoring commands
to the ASA.
client/server
computing
Distributed computing (processing) network systems in which transaction responsibilities are divided
into two parts: client (front end) and server (back end). Also called distributed computing. See also
RPC.
Client update Lets you update revisions of clients to which the update applies; provide a URL or IP address from
which to get the update; and, in the case of Windows clients, optionally notify users that they should
update their VPN client version.
command-specific
configuration mode
From global configuration mode, some commands enter a command-specific configuration mode. All
user EXEC, privileged EXEC, global configuration, and command-specific configuration commands
are available in this mode. See also global configuration mode, privileged EXEC mode, user EXEC
mode.
compression The process of encoding information using fewer bits or other information-bearing units than an
unencoded representation would use. Compression can reduce the size of transferring packets and
increase communication performance.
configuration, config,
config file
A file on the ASA that represents the equivalent of settings, preferences, and properties administered
by ASDM or the CLI.

Glossary
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Content
Rewriting/Transform
ation
Interprets and modifies applications so that they render correctly over a clientless SSL VPN
connection.
cookie A cookie is a object stored by a browser. Cookies contain information, such as user preferences, to
persistent storage.
CPU Central Processing Unit. Main processor.
CRC Cyclical Redundancy Check. Error-checking technique in which the frame recipient calculates a
remainder by dividing frame contents by a prime binary divisor and compares the calculated remainder
to a value stored in the frame by the sending node.
CRL Certificate Revocation List. A digitally signed message that lists all of the current but revoked
certificates listed by a given CA. A CRL is analogous to a book of stolen charge card numbers that
allow stores to reject bad credit cards. When certificates are revoked, they are added to a CRL. When
you implement authentication using certificates, you can choose to use CRLs or not. Using CRLs lets
you easily revoke certificates before they expire, but the CRL is generally only maintained by the CA
or an RA. If you are using CRLs and the connection to the CA or RA is not available when
authentication is requested, the authentication request will fail. See also CA, certificate, public key, RA.
CRV Call Reference Value. Used by H.225.0 to distinguish call legs signaled between two entities.
cryptography Encryption, authentication, integrity, keys and other services used for secure communication over
networks. See also VPN and IPsec.
crypto map A data structure with a unique name and sequence number that is used for configuring VPNs on the
ASA. A crypto map selects data flows that need security processing and defines the policy for these
flows and the crypto peer that traffic needs to go to. A crypto map is applied to an interface. Crypto
maps contain the ACLs, encryption standards, peers, and other parameters necessary to specify security
policies for VPNs using IKE and IPsec. See also VPN.
CTIQBE Computer Telephony Interface Quick Buffer Encoding. A protocol used in IP telephony between the
Cisco CallManager and CTI TAPI and JTAPI applications. CTIQBE is used by the TAPI/JTAPI
protocol inspection module and supports NAT, PAT, and bidirectional NAT. This protocol enables
Cisco IP SoftPhone and other Cisco TAPI/JTAPI applications to communicate with Cisco CallManager
for call setup and voice traffic across the ASA.
cut-through proxy Enables the ASA to provide faster traffic flow after user authentication. The cut-through proxy
challenges a user initially at the application layer. After the security appliance authenticates the user,
it shifts the session flow and all traffic flows directly and quickly between the source and destination
while maintaining session state information.
D
data confidentiality Describes any method that manipulates data so that no attacker can read it. This is commonly achieved
by data encryption and keys that are only available to the parties involved in the communication.
data integrity Describes mechanisms that, through the use of encryption based on secret key or public key
algorithms, allow the recipient of a piece of protected data to verify that the data has not been modified
in transit.

Glossary
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data origin
authentication
A security service where the receiver can verify that protected data could have originated only from
the sender. This service requires a data integrity service plus a key distribution mechanism, where a
secret key is shared only between the sender and receiver.
decryption Application of a specific algorithm or cipher to encrypted data so as to render the data comprehensible
to those who are authorized to see the information. See also encryption.
DES Data encryption standard. DES was published in 1977 by the National Bureau of Standards and is a
secret key encryption scheme based on the Lucifer algorithm from IBM. Cisco uses DES in classic
crypto (40-bit and 56-bit key lengths), IPsec crypto (56-bit key), and 3DES (triple DES), which
performs encryption three times using a 56-bit key. 3DES is more secure than DES but requires more
processing for encryption and decryption. See also AES, ESP.
DHCP Dynamic Host Configuration Protocol. Provides a mechanism for allocating IP addresses to hosts
dynamically, so that addresses can be reused when hosts no longer need them and so that mobile
computers, such as laptops, receive an IP address applicable to the LAN to which it is connected.
Diffie-Hellman A public key cryptography protocol that allows two parties to establish a shared secret over insecure
communications channels. Diffie-Hellman is used within IKE to establish session keys.
Diffie-Hellman is a component of Oakley key exchange.
Diffie-Hellman
Group 1, Group 2,
Group 5, Group 7
Diffie-Hellman refers to a type of public key cryptography using asymmetric encryption based on
large prime numbers to establish both Phase 1 and Phase 2 SAs. Group 1 provides a smaller prime
number than Group 2 but may be the only version supported by some IPsec peers. Diffe-Hellman
Group 5 uses a 1536-bit prime number, is the most secure, and is recommended for use with AES.
Group 7 has an elliptical curve field size of 163 bits and is for use with the Movian VPN client, but
works with any peer that supports Group 7 (ECC). See also VPN and encryption.
Note The group 7 command option was deprecated in ASA Version 8.0(4). Attempts to configure
group 7 will generate an error message and use group 5 instead.
digital certificate See certificate.
DMZ See interface.
DN Distinguished Name. Global, authoritative name of an entry in the OSI Directory (X.500).
DNS Domain Name System (or Service). An Internet service that translates domain names into IP
addresses.
DoS Denial of Service. A type of network attack in which the goal is to render a network service
unavailable.
DSL digital subscriber line. Public network technology that delivers high bandwidth over conventional
copper wiring at limited distances. DSL is provisioned via modem pairs, with one modem located at
a central office and the other at the customer site. Because most DSL technologies do not use the
whole bandwidth of the twisted pair, there is room remaining for a voice channel.
DSP digital signal processor. A DSP segments a voice signal into frames and stores them in voice packets.
DSS Digital Signature Standard. A digital signature algorithm designed by The US National Institute of
Standards and Technology and based on public-key cryptography. DSS does not do user datagram
encryption. DSS is a component in classic crypto, as well as the Redcreek IPsec card, but not in IPsec
implemented in Cisco IOS software.

Glossary
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Dynamic NAT See NAT and address translation.
Dynamic PAT Dynamic Port Address Translation. Dynamic PAT lets multiple outbound sessions appear to originate
from a single IP address. With PAT enabled, the ASA chooses a unique port number from the PAT IP
address for each outbound translation slot (xlate). This feature is valuable when an ISP cannot allocate
enough unique IP addresses for your outbound connections. The global pool addresses always come
first, before a PAT address is used. See also NAT, Static PAT, and xlate.
E
ECHO See ping, ICMP. See also inspection engine.
EGP Exterior Gateway Protocol. Replaced by BGP. The ASA does not support EGP. See also BGP.
EIGRP Enhanced Interior Gateway Routing Protocol. The ASA does not support EIGRP.
EMBLEM Enterprise Management BaseLine Embedded Manageability. A syslog format designed to be
consistent with the Cisco IOS system log format and is more compatible with CiscoWorks
management applications.
encryption Application of a specific algorithm or cipher to data so as to render the data incomprehensible to those
unauthorized to see the information. See also decryption.
ESMTP Extended SMTP. Extended version of SMTP that includes additional functionality, such as delivery
notification and session delivery. ESMTP is described in RFC 1869, SMTP Service Extensions.
ESP Encapsulating Security Payload. An IPsec protocol, ESP provides authentication and encryption
services for establishing a secure tunnel over an insecure network. For more information, refer to
RFCs 2406 and 1827.
F
failover, failover
mode
Failover lets you configure two ASAs so that one will take over operation if the other one fails. The
ASA supports two failover configurations, Active/Active failover and Active/Standby failover. Each
failover configuration has its own method for determining and performing failover. With
Active/Active failover, both units can pass network traffic. Active/Active failover lets you configure
load balancing on your network. Active/Active failover is only available on units running in multiple
context mode. With Active/Standby failover, only one unit passes traffic while the other unit waits in
a standby state. Active/Standby failover is available on units running in either single or multiple
context mode.
Fixup See inspection engine.
Flash, Flash memory A nonvolatile storage device used to store the configuration file when the ASA is powered down.
FQDN/IP Fully qualified domain name/IP address. IPsec parameter that identifies peers that are security
gateways.

Glossary
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FragGuard Provides IP fragment protection and performs full reassembly of all ICMP error messages and virtual
reassembly of the remaining IP fragments that are routed through the ASA.
FTP File Transfer Protocol. Part of the TCP/IP protocol stack, used for transferring files between hosts.
G
GGSN gateway GPRS support node. A wireless gateway that allows mobile cell phone users to access the
public data network or specified private IP networks.
global configuration
mode
Global configuration mode lets you change the ASA configuration. All user EXEC, privileged EXEC,
and global configuration commands are available in this mode. See also user EXEC mode, privileged
EXEC mode, command-specific configuration mode.
GMT Greenwich Mean Time. Replaced by UTC (Coordinated Universal Time) in 1967 as the world time
standard.
GPRS general packet radio service. A service defined and standardized by the European Telecommunication
Standards Institute. GPRS is an IP-packet-based extension of GSM networks and provides mobile,
wireless, data communications
GRE Generic Routing Encapsulation described in RFCs 1701 and 1702. GRE is a tunneling protocol that
can encapsulate a wide variety of protocol packet types inside IP tunnels, creating a virtual
point-to-point link to routers at remote points over an IP network. By connecting multiprotocol
subnetworks in a single-protocol backbone environment, IP tunneling using GRE allows network
expansion across a single protocol backbone environment.
GSM Global System for Mobile Communication. A digital, mobile, radio standard developed for mobile,
wireless, voice communications.
GTP GPRS tunneling protocol. GTP handles the flow of user packet data and signaling information
between the SGSN and GGSN in a GPRS network. GTP is defined on both the Gn and Gp interfaces
of a GPRS network.
H
H.225 A protocol used for TCP signaling in applications such as video conferencing. See also H.323 and
inspection engine.
H.225.0 An ITU standard that governs H.225.0 session establishment and packetization. H.225.0 actually
describes several different protocols: RAS, use of Q.931, and use of RTP.
H.245 An ITU standard that governs H.245 endpoint control.
H.320 Suite of ITU-T standard specifications for video conferencing over circuit-switched media, such as
ISDN, fractional T-1, and switched-56 lines. Extensions of ITU-T standard H.320 enable video
conferencing over LANs and other packet-switched networks, as well as video over the Internet.

Glossary
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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 Vo I P 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.

Glossary
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IKE Internet Key Exchange. IKE establishes a shared security policy and authenticates keys for services
(such as IPsec) that require keys. Before any IPsec traffic can be passed, each ASA must verify the
identity of its peer. Identification can be done by manually entering preshared keys into both hosts or
by a CA service. IKE is a hybrid protocol that uses part Oakley and part of another protocol suite
called SKEME inside the ISAKMP framework. IKE (formerly known as ISAKMP/Oakley) is defined
in RFC 2409.
IKE Extended
Authentication
IKE Extended Authenticate (Xauth) is implemented per the IETF draft-ietf-ipsec-isakmp-xauth-04.txt
(extended authentication). This protocol provides the capability of authenticating a user within IKE
using TACACS+ or RADIUS.
IKE Mode
Configuration
IKE Mode Configuration is implemented per the IETF draft-ietf-ipsec-isakmp-mode-cfg-04.txt. IKE
Mode Configuration provides a method for a security gateway to download an IP address (and other
network level configuration) to the VPN client as part of an IKE negotiation.
ILS Internet Locator Service. ILS is based on LDAP and is ILSv2 compliant. ILS was developed by
Microsoft for use with its NetMeeting, SiteServer, and Active Directory products.
IMAP Internet Message Access Protocol. Method of accessing e-mail or bulletin board messages kept on a
mail server that can be shared. IMAP permits client e-mail applications to access remote message
stores as if they were local without actually transferring the message.
implicit rule An access rule automatically created by the ASA based on default rules or as a result of user-defined
rules.
IMSI International Mobile Subscriber Identity. One of two components of a GTP tunnel ID, the other being
the NSAPI. See also NSAPI.
inside The first interface, usually port 1, that connects your internal, trusted network protected by the ASA.
See also interface, interface name.
inspection engine The ASA inspects certain application-level protocols to identify the location of embedded addressing
information in traffic. Inspection allows NAT to translate these embedded addresses and to update any
checksum or other fields that are affected by the translation. Because many protocols open secondary
TCP or UDP ports, each application inspection engine also monitors sessions to determine the port
numbers for secondary channels. The initial session on a well-known port is used to negotiate
dynamically assigned port numbers. The application inspection engine monitors these sessions,
identifies the dynamic port assignments, and permits data exchange on these ports for the duration of
the specific session. Some of the protocols that the ASA can inspect are CTIQBE, FTP, H.323, HTTP,
MGCP, SMTP, and SNMP.
interface The physical connection between a particular network and a ASA.
interface IP address The IP address of the ASA network interface. Each interface IP address must be unique. Two or more
interfaces must not be given the same IP address or IP addresses that are on the same IP network.
interface name Human-readable name assigned to the ASA network interface. The inside interface default name is
“inside” and the outside interface default name is “outside.” See also inside and outside.
interface PAT The use of PAT where the PAT IP address is also the IP address of the outside interface. See Dynamic
PAT, Static PAT.
Internet The global network that uses IP. Not a LAN. See also intranet.

Glossary
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intranet Intranetwork. A LAN that uses IP. See also network and Internet.
IP Internet Protocol. IP protocols are the most popular nonproprietary protocols because they can be used
to communicate across any set of interconnected networks and are equally well suited for LAN and
WA N communications.
IPS Intrusion Prevention Service. An in-line, deep-packet inspection-based solution that helps mitigate a
wide range of network attacks.
IP address An IP protocol address. A ASA interface ip_address. IP version 4 addresses are 32 bits in length. This
address space is used to designate the network number, optional subnetwork number, and a host
number. The 32 bits are grouped into four octets (8 binary bits), represented by 4 decimal numbers
separated by periods, or dots. The meaning of each of the four octets is determined by their use in a
particular network.
IP pool A range of local IP addresses specified by a name, and a range with a starting IP address and an ending
address. IP pools are used by DHCP and VPNs to assign local IP addresses to clients on the inside
interface.
IPsec IP Security. A framework of open standards that provides data confidentiality, data integrity, and data
authentication between participating peers. IPsec provides these security services at the IP layer. IPsec
uses IKE to handle the negotiation of protocols and algorithms based on local policy and to generate
the encryption and authentication keys to be used by IPsec. IPsec can protect one or more data flows
between a pair of hosts, between a pair of security gateways, or between a security gateway and a host.
IPsec Phase 1 The first phase of negotiating IPsec, includes the key exchange and the ISAKMP portions of IPsec.
IPsec Phase 2 The second phase of negotiating IPsec. Phase 2 determines the type of encryption rules used for
payload, the source and destination that will be used for encryption, the definition of interesting traffic
according to access lists, and the IPsec peer. IPsec is applied to the interface in Phase 2.
IPsec transform set A transform set specifies the IPsec protocol, encryption algorithm, and hash algorithm to use on traffic
matching the IPsec policy. A transform describes a security protocol (AH or ESP) with its
corresponding algorithms. The IPsec protocol used in almost all transform sets is ESP with the DES
algorithm and HMAC-SHA for authentication.
ISAKMP Internet Security Association and Key Management Protocol. A protocol framework that defines
payload formats, the mechanics of implementing a key exchange protocol, and the negotiation of a
security association. See IKE.
ISP Internet Service Provider. An organization that provides connection to the Internet via their services,
such as modem dial in over telephone voice lines or DSL.
J
JTAPI Java Telephony Application Programming Interface. A Java-based API supporting telephony
functions. See also TAPI.

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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.

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MGCP Media Gateway Control Protocol. Media Gateway Control Protocol is a protocol for the control of
VoIP calls by external call-control elements known as media gateway controllers or call agents.
MGCP merges the IPDC and SGCP protocols.
Mode See Access Modes.
Mode Config See IKE Mode Configuration.
Modular Policy
Framework
A means of configuring ASA features in a manner similar to Cisco IOS software Modular QoS CLI.
MS mobile station. Refers generically to any mobile device, such as a mobile handset or computer, that is
used to access network services. GPRS networks support three classes of MS, which describe the type
of operation supported within the GPRS and the GSM mobile wireless networks. For example, a Class
A MS supports simultaneous operation of GPRS and GSM services.
MS-CHAP Microsoft CHAP.
MTU maximum transmission unit. The maximum number of bytes in a packet that can flow efficiently
across the network with best response time. For Ethernet, the default MTU is 1500 bytes, but each
network can have different values, with serial connections having the smallest values. The MTU is
described in RFC 1191.
multicast Refers to a network addressing method in which the source transmits a packet to multiple destinations,
a multicast group, simultaneously. See also PIM, SMR.
N
N2H2 A third-party, policy-oriented filtering application that works with the ASA to control user web
access. N2H2 can filter HTTP requests based on the destination hostname, destination IP address,
username, and password. The N2H2 corporation was acquired by Secure Computing in October, 2003.
NAT Network Address Translation. Mechanism for reducing the need for globally unique IP addresses.
NAT allows an organization with addresses that are not globally unique to connect to the Internet by
translating those addresses into a globally routable address space.
NEM Network Extension Mode. Lets VPN hardware clients present a single, routable network to the remote
private network over the VPN tunnel.
NetBIOS Network Basic Input/Output System. A Microsoft protocol that supports Windows hostname
registration, session management, and data transfer. The ASA supports NetBIOS by performing NAT
of the packets for NBNS UDP port 137 and NBDS UDP port 138.
netmask See mask.
network In the context of ASA configuration, a network is a group of computing devices that share part of an
IP address space and not a single host. A network consists of multiple nodes or hosts. See also host,
Internet, intranet, IP, LAN, and node.
NMS network management system. System responsible for managing at least part of a network. An NMS is
generally a reasonably powerful and well-equipped computer, such as an engineering workstation.
NMSs communicate with agents to help keep track of network statistics and resources.

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node Devices such as routers and printers that would not normally be called hosts. See also host, network.
nonvolatile storage,
memory
Storage or memory that, unlike RAM, retains its contents without power. Data in a nonvolatile storage
device survives a power-off, power-on cycle.
NSAPI network service access point identifier. One of two components of a GTP tunnel ID, the other
component being the IMSI. See also IMSI.
NSSA not-so-stubby-area. An OSPF feature described by RFC 1587. NSSA was first introduced in Cisco
IOS software release 11.2. It is a nonproprietary extension of the existing stub area feature that allows
the injection of external routes in a limited fashion into the stub area.
NTLM NT Lan Manager. A Microsoft Windows challenge-response authentication method.
NTP Network Time Protocol.
O
Oakley A key exchange protocol that defines how to acquire authenticated keying material. The basic
mechanism for Oakley is the Diffie-Hellman key exchange algorithm. Oakley is defined in RFC 2412.
object grouping Simplifies access control by letting you apply access control statements to groups of network objects,
such as protocol, services, hosts, and networks.
OSPF Open Shortest Path First. OSPF is a routing protocol for IP networks. OSPF is a routing protocol
widely deployed in large networks because of its efficient use of network bandwidth and its rapid
convergence after changes in topology. The ASA supports OSPF.
OU Organizational Unit. An X.500 directory attribute.
outbound Refers to traffic whose destination is on an interface with lower security than the source interface.
outbound ACL An ACL applied to outbound traffic.
outside The first interface, usually port 0, that connects to other untrusted networks outside the ASA; the
Internet. See also interface, interface name, outbound.
P
PAC PPTP Access Concentrator. A device attached to one or more PSTN or ISDN lines capable of PPP
operation and of handling the PPTP protocol. The PAC needs to implement TCP/IP to pass traffic to
one or more PNSs. It may also tunnel non-IP protocols.
PAT See Dynamic PAT, interface PAT, and Static PAT.
PDP Packet Data Protocol.
Perfmon The ASA feature that gathers and reports a wide variety of feature statistics, such as
connections/second, xlates/second, and so on.

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PFS Perfect Forwarding Secrecy. PFS enhances security by using a different security key for the IPsec
Phase 1 and Phase 2 SAs. Without PFS, the same security key is used to establish SAs in both phases.
PFS ensures that a given IPsec SA key was not derived from any other secret (like some other keys).
In other words, if someone were to break a key, PFS ensures that the attacker would not be able to
derive any other key. If PFS were not enabled, someone could hypothetically break the IKE SA secret
key, copy all the IPsec protected data, and then use knowledge of the IKE SA secret to compromise
the IPsec SA setup by this IKE SA. With PFS, breaking IKE would not give an attacker immediate
access to IPsec. The attacker would have to break each IPsec SA individually.
Phase 1 See IPsec Phase 1.
Phase 2 See IPsec Phase 2.
PIM Protocol Independent Multicast. PIM provides a scalable method for determining the best paths for
distributing a specific multicast transmission to a group of hosts. Each host has registered using IGMP
to receive the transmission. See also PIM-SM.
PIM-SM Protocol Independent Multicast-Sparse Mode. With PIM-SM, which is the default for Cisco routers,
when the source of a multicast transmission begins broadcasting, the traffic is forwarded from one MC
router to the next, until the packets reach every registered host. See also PIM.
ping An ICMP request sent by a host to determine if a second host is accessible.
PIX Private Internet eXchange. The Cisco PIX 500 series ASAs ranged from compact, plug-and-play
desktop models for small/home offices to carrier-class gigabit models for the most demanding
enterprise and service provider environments. Cisco PIX ASAs provided robust, enterprise-class
integrated network security services to create a strong multilayered defense for fast changing network
environments. The PIX has been replaced by the Cisco ASA 5500 series.
PKCS12 A standard for the transfer of PKI-related data, such as private keys, certificates, and other data.
Devices supporting this standard let administrators maintain a single set of personal identity
information.
PNS PPTP Network Server. A PNS is envisioned to operate on general-purpose computing/server
platforms. The PNS handles the server side of PPTP. Because PPTP relies completely on TCP/IP and
is independent of the interface hardware, the PNS may use any combination of IP interface hardware
including LAN and WA N devices.
Policy NAT Lets you identify local traffic for address translation by specifying the source and destination
addresses (or ports) in an access list.
POP Post Office Protocol. Protocol that client e-mail applications use to retrieve mail from a mail server.
Pool See IP pool.
Port A field in the packet headers of TCP and UDP protocols that identifies the higher level service which
is the source or destination of the packet.
PPP Point-to-Point Protocol. Developed for dial-up ISP access using analog phone lines and modems.
PPPoE Point-to-Point Protocol over Ethernet. An IP protocol that encapsulates PPP packets and sends them
over a local network or the internet to establish a connection to a host, usually between a client and
an ISP.

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PPTP Point-to-Point Tunneling Protocol. PPTP was introduced by Microsoft to provide secure remote
access to Windows networks; however, because it is vulnerable to attack, PPTP is commonly used
only when stronger security methods are not available or are not required. PPTP Ports are pptp,
1723/tcp, 1723/udp, and pptp. For more information about PPTP, see RFC 2637. See also PAC, PPTP
GRE, PPTP GRE tunnel, PNS, PPTP session, and PPTP TCP.
PPTP GRE Version 1 of GRE for encapsulating PPP traffic.
PPTP GRE tunnel A tunnel defined by a PNS-PAC pair. The tunnel protocol is defined by a modified version of GRE.
The tunnel carries PPP datagrams between the PAC and the PNS. Many sessions are multiplexed on a
single tunnel. A control connection operating over TCP controls the establishment, release, and
maintenance of sessions and of the tunnel itself.
PPTP session PPTP is connection-oriented. The PNS and PAC maintain the state for each user that is attached to a
PAC. A session is created when an end-to-end PPP connection is attempted between a dial-up user and
the PNS. The datagrams related to a session are sent over the tunnel between the PAC and PNS.
PPTP TCP Standard TCP session over which PPTP call control and management information is passed. The
control session is logically associated with, but separate from, the sessions being tunneled through a
PPTP tunnel.
preshared key A preshared key provides a method of IKE authentication that is suitable for networks with a limited,
static number of IPsec peers. This method is limited in scalability because the key must be configured
for each pair of IPsec peers. When a new IPsec peer is added to the network, the preshared key must
be configured for every IPsec peer with which it communicates. Using certificates and CAs provides
a more scalable method of IKE authentication.
primary, primary unit The ASA normally operating when two units, a primary and secondary, are operating in failover mode.
privileged EXEC
mode
The highest privilege level at the ASA CLI. Any user EXEC mode command will work in privileged
EXEC mode. The privileged EXEC mode prompt appears as follows after you enter the enable
command:
hostname> enable
hostname#
See also command-specific configuration mode, global configuration mode, user EXEC mode.
protocol, protocol
literals
A standard that defines the exchange of packets between network nodes for communication. Protocols
work together in layers. Protocols are specified in the ASA configuration as part of defining a security
policy by their literal values or port numbers. Possible ASA protocol literal values are ahp, eigrp, esp,
gre, icmp, igmp, igrp, ip, ipinip, ipsec, nos, ospf, pcp, snp, tcp, and udp.
Proxy-ARP Enables the ASA to reply to an ARP request for IP addresses in the global pool. See also ARP.
public key A public key is one of a pair of keys that are generated by devices involved in public key infrastructure.
Data encrypted with a public key can only be decrypted using the associated private key. When a
private key is used to produce a digital signature, the receiver can use the public key of the sender to
verify that the message was signed by the sender. These characteristics of key pairs provide a scalable
and secure method of authentication over an insecure media, such as the Internet.

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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.