Configuring Objects

Objects are reusable components for use in your configuration. They can be defined and used in ASA configurations in the place of inline IP addresses. Objects make it easy to maintain your configurations because you can modify an object in one place and have it be reflected in all other places that are referencing it. Without objects you would have to modify the parameters for every feature when required, instead of just once. For example, if a network object defines an IP address and subnet mask, and you want to change the address, you only need to change it in the object definition, not in every feature that refers to that IP address.

This chapter describes how to configure objects, and it includes the following sections:

Configuring Objects and Groups

This section includes the following topics:

Information About Objects and Groups

The ASA supports objects and object groups. You can attach or detach objects from one or more object groups when needed, ensuring that the objects are not duplicated but can be re-used wherever needed.

This section includes the following topics:

Information About Objects

Objects are created in and used by the ASA in the place of an inline IP address in any given configuration. You can define an object with a particular IP address and netmask pair or a protocol (and, optionally, a port) and use this object in several configurations. The advantage is that whenever you want to modify the configurations created to this IP address or protocol, you do not need to modify all rules in the running configuration. You can modify the object, and then the change automatically applies to all rules that use the specified object. You can configure two types of objects: network objects and service objects. These objects can be used in Network Address Translation (NAT), access lists, and object groups.

Information About Object Groups

By grouping like objects together, you can use the object group in an ACE instead of having to enter an ACE for each object separately. You can create the following types of object groups:

  • Protocol
  • Network
  • Service
  • ICMP type

For example, consider the following three object groups:

  • MyServices—Includes the TCP and UDP port numbers of the service requests that are allowed access to the internal network.
  • TrustedHosts—Includes the host and network addresses allowed access to the greatest range of services and servers.
  • PublicServers—Includes the host addresses of servers to which the greatest access is provided.

After creating these groups, you could use a single ACE to allow trusted hosts to make specific service requests to a group of public servers.

You can also nest object groups in other object groups.

Licensing Requirements for Objects and Groups

The following table shows the licensing requirements for this feature:

 

Model
License Requirement

All models

Base License.

Guidelines and Limitations for Objects and Groups

This section includes the guidelines and limitations for this feature.

Context Mode Guidelines

Supported in single and multiple context mode.

Firewall Mode Guidelines

Supported in routed and transparent firewall modes.

IPv6 Guidelines

Supports IPv6, with limitations. (See the “Additional Guidelines and Limitations” section.)

Additional Guidelines and Limitations

The following guidelines and limitations apply to object groups:

  • Objects and object groups share the same name space.
  • Object groups must have unique names. While you might want to create a network object group named “Engineering” and a service object group named “Engineering,” you need to add an identifier (or “tag”) to the end of at least one object group name to make it unique. For example, you can use the names “Engineering_admins” and “Engineering_hosts” to make the object group names unique and to aid in identification.
  • You cannot remove an object group or make an object group empty if it is used in a command.
  • The ASA does not support IPv6 nested object groups, so you cannot group an object with IPv6 entities under another IPv6 object group.

Configuring Objects

This section includes the following topics:

Configuring a Network Object

A network object contains a single IP address/mask pair. Network objects can be of three types: host, subnet, or range.

You can also configure auto NAT as part of the object definition; see “Configuring Network Object NAT,” for more information.

Detailed Steps

 

Command
Purpose

Step 1
object network obj_name
 
hostname(config)# object-network OBJECT1

Creates a new network object. The obj_name is a text string up to 64 characters in length and can be any combination of letters, digits, and the following characters:

  • underscore “_”
  • dash “-”
  • period “.”

The prompt changes to network object configuration mode.

Step 2
{ host ip_addr | subnet net_addr net_mask | range ip_addr_1 ip_addr_2 }
 
hostname(config-network-object)# host 10.2.2.2

Assigns the IP address to the named object. You can configure a host address, a subnet, or a range of addresses.

Step 3
description text
 
hostname(config-network-object)# description Engineering Network

Adds a description to the object.

Examples

To create a network object, enter the following commands:

hostname (config)# object network OBJECT1
hostname (config-network-object)# host 10.2.2.2

Configuring a Service Object

A service object contains a protocol and optional source and/or destination port.

Detailed Steps

 

Command
Purpose

Step 1
object service obj_name
 
hostname(config)# object-service SERVOBJECT1

Creates a new service object. The obj_name is a text string up to 64 characters in length and can be any combination of letters, digits, and the following characters:

  • underscore “_”
  • dash “-”
  • period “.”

The prompt changes to service object configuration mode.

Step 2
service { protocol | icmp icmp-type | icmp6 icmp6-type | { tcp | udp } [ source operator port ] [ destination operator port ]}
 
hostname(config-service-object)# service tcp source eq www destination eq ssh

Creates a service object for the source mapped address.

The protocol argument specifies an IP protocol name or number.

The icmp, tcp, or udp keywords specify that this service object is for either the ICMP, TCP, or UDP protocol.

The icmp-type argument names the ICMP type.

The icmp6 keyword specifies that the service type is for ICMP version 6 connections.

The icmp6-type argument names the ICMP version 6 type.

The source keyword specifies the source port.

The destination keyword specifies the destination port.

The operator port argument specifies a single port/code value that supports configuring the port for the protocol. You can specify “eq,” “neq,” “lt,” “gt,” and “range” when configuring a port for TCP or UDP. The “range” operator lists the beginning port and ending port.

Example

To create a service object, enter the following commands:

hostname (config)# object service SERVOBJECT1
hostname (config-service-object)# service tcp source eq www destination eq ssh

Configuring Object Groups

This section includes the following topics:

Adding a Protocol Object Group

To add or change a protocol object group, perform the steps in this section. After you add the group, you can add more objects as required by following this procedure again for the same group name and specifying additional objects. You do not need to reenter existing objects; the commands you already set remain in place unless you remove them with the no form of the command.

Detailed Steps

 

Command
Purpose

Step 1
object-group protocol obj _ grp_id
 
hostname(config)# object-group protocol tcp_udp_icmp

Adds a protocol group. The obj_grp_id is a text string up to 64 characters in length and can be any combination of letters, digits, and the following characters:

  • underscore “_”
  • dash “-”
  • period “.”

The prompt changes to protocol configuration mode.

Step 2
description text
 
hostname(config-protocol)# description New Group

(Optional) Adds a description. The description can be up to 200 characters.

Step 3
protocol-object protocol
 
hostname(config-protocol)# protocol-object tcp
 

Defines the protocols in the group. Enter the command for each protocol. The protocol is the numeric identifier of the specified IP protocol (1 to 254) or a keyword identifier (for example, icmp, tcp, or udp). To include all IP protocols, use the keyword ip. For a list of protocols that you can specify, see the “Protocols and Applications” section.

Example

To create a protocol group for TCP, UDP, and ICMP, enter the following commands:

hostname (config)# object-group protocol tcp_udp_icmp
hostname (config-protocol)# protocol-object tcp
hostname (config-protocol)# protocol-object udp
hostname (config-protocol)# protocol-object icmp

Adding a Network Object Group

A network object group supports IPv4 and IPv6 addresses.

To add or change a network object group, perform the steps in this section. After you add the group, you can add more objects as required by following this procedure again for the same group name and specifying additional objects. You do not need to reenter existing objects; the commands you already set remain in place unless you remove them with the no form of the command.

Detailed Steps

 

Command
Purpose

Step 1
object-group network grp_id
 
hostname(config)# object-group network admins

Adds a network group.

The grp_id is a text string up to 64 characters in length and can be any combination of letters, digits, and the following characters:

  • underscore “_”
  • dash “-”
  • period “.”

The prompt changes to protocol configuration mode.

Step 2
description text
 
hostname(config-network)# Administrator Addresses

(Optional) Adds a description. The description can be up to 200 characters.

Step 3
network-object { object name | host ip_address | ip_address mask}
 
hostname(config-network)# network-object host 10.2.2.4

The object keyword adds an additional object to the network object group.

Defines the networks in the group. Enter the command for each network or address.

Example

To create a network group that includes the IP addresses of three administrators, enter the following commands:

hostname (config)# object-group network admins
hostname (config-protocol)# description Administrator Addresses
hostname (config-protocol)# network-object host 10.2.2.4
hostname (config-protocol)# network-object host 10.2.2.78
hostname (config-protocol)# network-object host 10.2.2.34

Adding a Service Object Group

To add or change a service object group, perform the steps in this section. After you add the group, you can add more objects as required by following this procedure again for the same group name and specifying additional objects. You do not need to reenter existing objects; the commands you already set remain in place unless you remove them with the no form of the command.

Detailed Steps

 

Command
Purpose

Step 1
object-group service grp_id { tcp | udp | tcp-udp }
 
hostname(config)# object-group service services1 tcp-udp

Adds a service group.

The object keyword adds an additional object to the service object group.

The grp_id is a text string up to 64 characters in length and can be any combination of letters, digits, and the following characters:

  • underscore “_”
  • dash “-”
  • period “.”

Specify the protocol for the services (ports) you want to add with either the tcp, udp, or tcp-udp keywords. Enter the tcp-udp keyword if your service uses both TCP and UDP with the same port number, for example, DNS (port53).

The prompt changes to service configuration mode.

Step 2
description text
 
hostname(config-service)# description DNS Group

(Optional) Adds a description. The description can be up to 200 characters.

Step 3
port-object { eq port | range begin_port end_port }
 
hostname(config-service)# port-object eq domain

Defines the ports in the group. Enter the command for each port or range of ports. For a list of permitted keywords and well-known port assignments, see the “Protocols and Applications” section.

Example

To create service groups that include DNS (TCP/UDP), LDAP (TCP), and RADIUS (UDP), enter the following commands:

hostname (config)# object-group service services1 tcp-udp
hostname (config-service)# description DNS Group
hostname (config-service)# port-object eq domain
 
hostname (config)# object-group service services2 udp
hostname (config-service)# description RADIUS Group
hostname (config-service)# port-object eq radius
hostname (config-service)# port-object eq radius-acct
 
hostname (config)# object-group service services3 tcp
hostname (config-service)# description LDAP Group
hostname (config-service)# port-object eq ldap

Adding an ICMP Type Object Group

To add or change an ICMP type object group, perform the steps in this section. After you add the group, you can add more objects as required by following this procedure again for the same group name and specifying additional objects. You do not need to reenter existing objects; the commands you already set remain in place unless you remove them with the no form of the command.

Detailed Steps

 

Command
Purpose

Step 1
object-group icmp-type grp_id
 
hostname(config)# object-group icmp-type ping
 

Adds an ICMP type object group. The grp_id is a text string up to 64 characters in length and can be any combination of letters, digits, and the following characters:

  • underscore “_”
  • dash “-”
  • period “.”

The prompt changes to ICMP type configuration mode.

Step 2
description text
 
hostname(config-icmp-type)# description Ping Group

(Optional) Adds a description. The description can be up to 200 characters.

Step 3
icmp-object icmp-type
 
hostname(config-icmp-type)# icmp-object echo-reply

Defines the ICMP types in the group. Enter the command for each type. For a list of ICMP types, see the“ICMP Types” section.

Example

Create an ICMP type group that includes echo-reply and echo (for controlling ping) by entering the following commands:

hostname (config)# object-group icmp-type ping
hostname (config-service)# description Ping Group
hostname (config-service)# icmp-object echo
hostname (config-service)# icmp-object echo-reply
 

Nesting Object Groups

You can nest object groups hierarchically so that one object group can contain other object groups of the same type and you can mix and match nested group objects and regular objects within an object group. The ASA does not support IPv6 nested object groups, however, so you cannot group an object with IPv6 entities under another IPv6 object-group.

To nest an object group within another object group of the same type, first create the group that you want to nest (see the “Configuring Object Groups” section), and then perform the steps in this section.

Detailed Steps

 

Command
Purpose

Step 1
object-group group {{ protocol | network | icmp-type } grp_id | service grp_id { tcp | udp | tcp-udp }}
 
hostname(config)# object-group network Engineering_group
 

Adds or edits the specified object group type under which you want to nest another object group.

The service _grp_id is a text string up to 64 characters in length and can be any combination of letters, digits, and the following characters:

  • underscore “_”
  • dash “-”
  • period “.”

Step 2
group-object group_id
 
hostname(config-network)# group-object Engineering_groups

Adds the specified group under the object group you specified in Step 1. The nested group must be of the same type. You can mix and match nested group objects and regular objects within an object group.

Examples

Create network object groups for privileged users from various departments by entering the following commands:

hostname (config)# object-group network eng
hostname (config-network)# network-object host 10.1.1.5
hostname (config-network)# network-object host 10.1.1.9
hostname (config-network)# network-object host 10.1.1.89
 
hostname (config)# object-group network hr
hostname (config-network)# network-object host 10.1.2.8
hostname (config-network)# network-object host 10.1.2.12
 
hostname (config)# object-group network finance
hostname (config-network)# network-object host 10.1.4.89
hostname (config-network)# network-object host 10.1.4.100
 

You then nest all three groups together as follows:

hostname (config)# object-group network admin
hostname (config-network)# group-object eng
hostname (config-network)# group-object hr
hostname (config-network)# group-object finance
 

You only need to specify the admin object group in your ACE as follows:

hostname (config)# access-list ACL_IN extended permit ip object-group admin host 209.165.201.29

Removing Object Groups

You can remove a specific object group or remove all object groups of a specified type; however, you cannot remove an object group or make an object group empty if it is used in an access list.

Detailed Step

 

Step 1

Do one of the following:

 

no object-group grp_id

 
hostname(config)# no object-group Engineering_host
 

Removes the specified object group. The grp_id is a text string up to 64 characters in length and can be any combination of letters, digits, and the following characters:

  • underscore “_”
  • dash “-”
  • period “.”

 
clear object-group [ protocol | network | services | icmp-type ]
 

hostname(config)# clear-object group network

Removes all object groups of the specified type.

note.gif

Noteblank.gif If you do not enter a type, all object groups are removed.

Monitoring Objects and Groups

To monitor objects and groups, enter the following commands:

 

Command
Purpose
show access-list

Displays the access list entries that are expanded out into individual entries without their object groupings.
show running-config object-group

Displays all current object groups.
show running-config object-group grp_id

Displays the current object groups by their group ID.
show running-config object-group grp_type

Displays the current object groups by their group type.

Feature History for Objects and Groups

Table 1 lists each feature change and the platform release in which it was implemented.

 

Table 1 Feature History for Object Groups

Feature Name
Releases
Feature Information

Object groups

7.0(1)

Object groups simplify access list creation and maintenance.

We introduced or modified the following commands: object-group protocol, object-group network, object-group service, object-group icmp_type.

Objects

8.3(1)

Object support was introduced.

We introduced or modified the following commands:

object-network, object-service, object-group network, object-group service, network object, access-list extended, access-list webtype, access-list remark.

Configuring Regular Expressions

A regular expression matches text strings either literally as an exact string, or by using metacharacters so that you can match multiple variants of a text string. You can use a regular expression to match the content of certain application traffic; for example, you can match a URL string inside an HTTP packet. This section describes how to create a regular expression and includes the following topics:

Creating a Regular Expression

A regular expression matches text strings either literally as an exact string, or by using metacharacters so you can match multiple variants of a text string. You can use a regular expression to match the content of certain application traffic; for example, you can match a URL string inside an HTTP packet.

Guidelines

Use Ctrl+V to escape all of the special characters in the CLI, such as question mark (?) or a tab. For example, type d[Ctrl+V]?g to enter d?g in the configuration.

See the regex command in the command reference for performance impact information when matching a regular expression to packets.

note.gif

Noteblank.gif As an optimization, the ASA searches on the deobfuscated URL. Deobfuscation compresses multiple forward slashes (/) into a single slash. For strings that commonly use double slashes, like “http://”, be sure to search for “http:/” instead.

Table 13-2 lists the metacharacters that have special meanings.

 

Table 13-2 regex Metacharacters

Character
Description
Notes

.

Dot

Matches any single character. For example, d.g matches dog, dag, dtg, and any word that contains those characters, such as doggonnit.

( exp )

Subexpression

A subexpression segregates characters from surrounding characters, so that you can use other metacharacters on the subexpression. For example, d(o|a)g matches dog and dag, but do|ag matches do and ag. A subexpression can also be used with repeat quantifiers to differentiate the characters meant for repetition. For example, ab(xy){3}z matches abxyxyxyz.

|

Alternation

Matches either expression it separates. For example, dog|cat matches dog or cat.

?

Question mark

A quantifier that indicates that there are 0 or 1 of the previous expression. For example, lo?se matches lse or lose.

Note You must enter Ctrl+V and then the question mark or else the help function is invoked.

*

Asterisk

A quantifier that indicates that there are 0, 1 or any number of the previous expression. For example, lo*se matches lse, lose, loose, and so on.

+

Plus

A quantifier that indicates that there is at least 1 of the previous expression. For example, lo+se matches lose and loose, but not lse.

{ x } or { x ,}

Minimum repeat quantifier

Repeat at least x times. For example, ab(xy){2,}z matches abxyxyz, abxyxyxyz, and so on.

[ abc ]

Character class

Matches any character in the brackets. For example, [abc] matches a, b, or c.

[^ abc ]

Negated character class

Matches a single character that is not contained within the brackets. For example, [^abc] matches any character other than a, b, or c. [^A-Z] matches any single character that is not an uppercase letter.

[ a - c ]

Character range class

Matches any character in the range. [a-z] matches any lowercase letter. You can mix characters and ranges: [abcq-z] matches a, b, c, q, r, s, t, u, v, w, x, y, z, and so does [ a-cq-z].

The dash (-) character is literal only if it is the last or the first character within the brackets: [abc-] or [-abc].

“”

Quotation marks

Preserves trailing or leading spaces in the string. For example, “ test” preserves the leading space when it looks for a match.

^

Caret

Specifies the beginning of a line.

\

Escape character

When used with a metacharacter, matches a literal character. For example, \[ matches the left square bracket.

char

Character

When character is not a metacharacter, matches the literal character.

\r

Carriage return

Matches a carriage return 0x0d.

\n

Newline

Matches a new line 0x0a.

\t

Tab

Matches a tab 0x09.

\f

Formfeed

Matches a form feed 0x0c.

\x NN

Escaped hexadecimal number

Matches an ASCII character using hexadecimal (exactly two digits).

\ NNN

Escaped octal number

Matches an ASCII character as octal (exactly three digits). For example, the character 040 represents a space.

Detailed Steps

Step 1blank.gif To test a regular expression to make sure it matches what you think it will match, enter the following command:

hostname(config)# test regex input_text regular_expression
 

Where the input_text argument is a string you want to match using the regular expression, up to 201 characters in length.

The regular_expression argument can be up to 100 characters in length.

Use Ctrl+V to escape all of the special characters in the CLI. For example, to enter a tab in the input text in the test regex command, you must enter test regex “test[Ctrl+V Tab]” “test\t”.

If the regular expression matches the input text, you see the following message:

INFO: Regular expression match succeeded.
 

If the regular expression does not match the input text, you see the following message:

INFO: Regular expression match failed.
 

Step 2blank.gif To add a regular expression after you tested it, enter the following command:

hostname(config)# regex name regular_expression
 

Where the name argument can be up to 40 characters in length.

The regular_expression argument can be up to 100 characters in length.

 

Examples

The following example creates two regular expressions for use in an inspection policy map:

hostname(config)# regex url_example example\.com
hostname(config)# regex url_example2 example2\.com
 

Creating a Regular Expression Class Map

A regular expression class map identifies one or more regular expressions. You can use a regular expression class map to match the content of certain traffic; for example, you can match URL strings inside HTTP packets.

Detailed Steps

Step 1blank.gif Create one or more regular expressions according to the “Configuring Regular Expressions” section.

Step 2blank.gif Create a class map by entering the following command:

hostname(config)# class-map type regex match-any class_map_name
hostname(config-cmap)#
 

Where class_map_name is a string up to 40 characters in length. The name “class-default” is reserved. All types of class maps use the same name space, so you cannot reuse a name already used by another type of class map.

The match-any keyword specifies that the traffic matches the class map if it matches at least one of the regular expressions.

The CLI enters class-map configuration mode.

Step 3blank.gif (Optional) Add a description to the class map by entering the following command:

hostname(config-cmap)# description string
 

Step 4blank.gif Identify the regular expressions you want to include by entering the following command for each regular expression:

hostname(config-cmap)# match regex regex_name
 

 

Examples

The following example creates two regular expressions, and adds them to a regular expression class map. Traffic matches the class map if it includes the string “example.com” or “example2.com.”

hostname(config)# regex url_example example\.com
hostname(config)# regex url_example2 example2\.com
hostname(config)# class-map type regex match-any URLs
hostname(config-cmap)# match regex url_example
hostname(config-cmap)# match regex url_example2
 

Scheduling Extended Access List Activation

This section includes the following topics:

Information About Scheduling Access List Activation

You can schedule each ACE in an access list to be activated at specific times of the day and week by applying a time range to the ACE.

Licensing Requirements for Scheduling Access List Activation

The following table shows the licensing requirements for this feature:

 

Model
License Requirement

All models

Base License.

Guidelines and Limitations for Scheduling Access List Activation

This section includes the guidelines and limitations for this feature.

Context Mode Guidelines

Supported in single and multiple context mode.

Firewall Mode Guidelines

Supported in routed and transparent firewall modes.

IPv6 Guidelines

Supports IPv6.

Additional Guidelines and Limitations

The following guidelines and limitations apply to using object groups with access lists:

  • Users could experience a delay of approximately 80 to 100 seconds after the specified end time for the ACL to become inactive. For example, if the specified end time is 3:50, because the end time is inclusive, the command is picked up anywhere between 3:51:00 and 3:51:59. After the command is picked up, the ASA finishes any currently running task and then services the command to deactivate the ACL.
  • Multiple periodic entries are allowed per time-range command. If a time-range command has both absolute and periodic values specified, then the periodic commands are evaluated only after the absolute start time is reached, and they are not further evaluated after the absolute end time is reached.

Configuring and Applying Time Ranges

You can add a time range to implement a time-based access list. To identify the time range, perform the steps in this section.

Detailed Steps

 

Command
Purpose

Step 1
time-range name
 
hostname(config)# time range Sales
 

Identifies the time-range name.

Step 2

Do one of the following:

 
periodic days-of-the-week time to [ days-of-the-week ] time
 
Example :
hostname(config-time-range)# periodic monday 7:59 to friday 17:01
 

Specifies a recurring time range.

You can specify the following values for days-of-the-week :

  • monday, tuesday, wednesday, thursday, friday, saturday, or sunday.
  • daily
  • weekdays
  • weekend

The time is in the format hh : mm. For example, 8:00 is 8:00 a.m. and 20:00 is 8:00 p.m.

 
absolute start time date [ end time date ]
 
hostname(config-time-range)# absolute start 7:59 2 january 2009

Specifies an absolute time range.

The time is in the format hh : mm. For example, 8:00 is 8:00 a.m. and 20:00 is 8:00 p.m.

The date is in the format day month year ; for example, 1 january 2006.

Step 3
access-list access_list_ name [ extended ] {deny | permit}... [ time-range name ]
 
hostname(config)# access list Marketing extended deny tcp host 209.165.200.225 host 209.165 201.1 time-range Pacific_Coast

Applies the time range to an ACE.

note.gif

Noteblank.gif If you also enable logging for the ACE, use the log keyword before the time-range keyword. If you disable the ACE using the inactive keyword, use the inactive keyword as the last keyword.

See “Adding an Extended Access List,” for complete access-list command syntax.

Example

The following example binds an access list named “Sales” to a time range named “New_York_Minute”:

hostname(config)# access-list Sales line 1 extended deny tcp host 209.165.200.225 host 209.165.201.1 time-range New_York_Minute

Configuration Examples for Scheduling Access List Activation

The following is an example of an absolute time range beginning at 8:00 a.m. on January 1, 2006. Because no end time and date are specified, the time range is in effect indefinitely.

hostname(config)# time-range for2006
hostname(config-time-range)# absolute start 8:00 1 january 2006
 

The following is an example of a weekly periodic time range from 8:00 a.m. to 6:00 p.m on weekdays:

hostname(config)# time-range workinghours
hostname(config-time-range)# periodic weekdays 8:00 to 18:00

Feature History for Scheduling Access List Activation

Table 13-3 lists each feature change and the platform release in which it was implemented.

 

Table 13-3 Feature History for Scheduling Access List Activation
Feature Name
Releases
Feature Information

Scheduling access list activation

7.0

You can schedule each ACE in an access list to be activated at specific times of the day and week.

We introduced or mofied the following commands: object-group protocol, object-group network, object-group service, object-group icmp_type.