Flexible Packet Matching

Last Updated: January 19, 2012

Flexible Packet Matching (FPM) is an access control list (ACL) pattern matching tool, providing more thorough and customized packet filters. FPM enables users to match on arbitrary bits of a packet at an arbitrary depth in the packet header and payload. FPM removes constraints to specific fields that had limited packet inspection.

FPM enables users to create their own stateless packet classification criteria and to define policies with multiple actions (such as drop, log, or send Internet Control Message Protocol [ICMP] unreachable1) to immediately block new viruses, worms, and attacks.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the Feature Information Table at the end of this document.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.

Restrictions for Flexible Packet Matching

  • In Cisco IOS Release 12.4(4)T, FPM is available only in advanced security images.
  • In Cisco IOS Release 12.2(18)ZY, FPM is available in ipbase and ipservices images for the Supervisor Engine 32 Programmable Intelligent Services Accelerator (PISA) platform.
  • Although access to an XML editor is not required, XML will ease the creation of protocol header description files (PHDFs).
  • FPM cannot be used to mitigate an attack that requires stateful classification.
  • Because FPM is stateless, it cannot keep track of port numbers being used by protocols that dynamically negotiate ports. Thus port numbers must be explicitly specified when using FPM.
  • FPM cannot perform IP fragmentation or TCP flow reassembly.
  • FPM inspects only IPv4 unicast packets.
  • FPM cannot classify packets with IP options.
  • FPM does not support multicast packet inspection.
  • FPM is not supported on tunnel and Multiprotocol Label Switching (MPLS) interfaces.
  • FPM cannot be configured on FlexWAN cards.
  • Noninitial fragments will not be matched by the FPM engine.
  • Offset can be a constant only in a match start construct.
  • FPM cannot match across packets.
  • Mapping of FPM policies to the control plane is not supported.

Information About Flexible Packet Matching

Flexible Packet Matching Functional Overview

FPM allows customers to create their own filtering policies that can immediately detect and block new viruses and attacks.

A filtering policy is defined via the following tasks:

  • Load a PHDF (for protocol header field matching)
  • Define a class map and define the protocol stack chain (traffic class)
  • Define a service policy (traffic policy)
  • Apply the service policy to an interface

Protocol Header Description File

Protocol headers are defined in separate files called PHDFs; the field names that are defined within the PHDFs are used for defining the packet filters. A PHDF is a file that allows the user to leverage the flexibility of XML to describe almost any protocol header. The important components of the PHDF are the version, the XML file schema location, and the protocol field definitions. The protocol field definitions name the appropriate field in the protocol header, allow for a comment describing the field, provide the location of the protocol header field in the header (the offset is relative to the start of the protocol header), and provide the length of the field. Users can choose to specify the measurement in bytes or in bits.


Note
The total length of the header must be specified at the end of each PHDF.

Note
When redundant sup PHDF files are used by the FPM policy, the files should also be on the standby sup's corresponding disk. If the files are not available the FPM policy will not work after the switchover.

Users can write their own custom PHDFs via XML for existing or proprietary protocols. However, the following standard PHDFs can also be loaded onto the router via the load protocol command: ether.phdf, ip.phdf, tcp.phdf, and udp.phdf.


Note
Because PHDFs are defined via XML, they are not shown in a running configuration. However, you can use the show protocol phdf command to verify the loaded PHDF.

Standard PHDFs are available on Cisco.com at the following URL: http://www.cisco.com/cgi-bin/tablebuild.pl/fpm

Filter Description

A filter description is a definition of a traffic class that can contain the header fields defined in a PHDF (using the match field command). If a PHDF is not loaded, the traffic class can be defined through the datagram header start (Layer 2) or the network header start (Layer 3) (using the match start command). If a PHDF has been loaded onto the router, the class specification begins with a list of the protocol headers in the packet.

A filter definition also includes the policy map; that is, after a class map has been defined, a policy map is needed to bind the match to an action. A policy map is an ordered set of classes and associated actions, such as drop, log, or send ICMP unreachable.

For information on how to configure a class map and a policy map for FPM, see the How to Configure a Flexible Packet Matching Traffic Class and Traffic Policy section.

Traffic Classification Definition Files for the Flexible Packet Matching XML Configuration

FPM uses a traffic classification definition file (TCDF) to define policies that can block attacks on the network. Before Cisco IOS Release 12.4(6)T, FPM defined traffic classes (class maps), policies (policy maps), and service policies (attach policy maps to class maps) through the use of the command line interface (CLI). With TCDFs, FPM can use XML as an alternative to the CLI to define classes of traffic and specify actions to apply to the traffic classes. Traffic classification behavior is the same whether you create the behavior using a TCDF or configure it using CLI commands. Once a TCDF is created, it can be loaded on any FPM-enabled device in the network.


Note
TCDFs are supported only in Cisco IOS Release 12.4(6)T and later T-train releases.

For more information on configuring FPM using TCDFs, see "Flexible Packet Matching XML Configuration".

FPM on the Catalyst 6500 Equipped with PISA Overview

The PISA functions as a network processor-based daughter card that is mounted on the Catalyst 6500 Supervisor. PISA provides a superset of the multilater switch feature card 2a (MSFC2a) capabilities. In addition to performing all of the same functions as the MSFC2a, PISA provides dedicated hardware to accelerate certain features such as FPM.

Network-Based Application Recognition (NBAR) occurs before FPM; thus, packets that are dropped by FPM are processed by NBAR.

Logging FPM Activity

In software-based FPM logging, every flow is logged and aggregated statistics are provided for each flow. Logging every flow for FPM on PISA would overwhelm the CPU; thus, only selective packets are logged. That is, when a packet matches a policy that is to be logged or the first time, the packet is logged, time-stamped, and stored. For every subsequent packet that matches any policy with a log action, the packet is checked for the difference between the current time (which is clocked by the global timer) and the last time stamp. If the current time is later than the last time stamp, the packet is logged and the "stamp time" is updated with the current time.

Memory Requirements


Note
Because memory requirements vary among system configurations, the requirements listed in this document are estimates.
  • PISA will support a maximum of 1024 interfaces; however, it is expected that no more than 256 interfaces will be configured with FPM.
  • A maximum of 32 classes per policy map, and a total of 1024 classes globally, are supported.
  • A maximum of 32 filters (such as match entries) per class map are supported. (However, some optimizations for better performance are possible with match-any type of class maps that have filters starting at the same offset and the same size.)

Encrypted TCDF Support

TCDFs provide preconfigured FPM filters written in XML format that can be directly loaded onto a router. The XML format prohibits the Cisco Product Security Incident Response Team (PSIRT) from being able to provide public TCDF filters because it would expose the vulnerability to potential attackers. This information could then be used to exploit PSIRT vulnerabilities in some systems.

FPM encrypted TCDF (eTCDF) filter support will provide encrypted FPM filters. Applying the PSIRT provided eTCDF FPM filter will protect routers from PSIRT incidents, allowing time to certify new Cisco IOS releases that contains the PSIRT fixes.

To enter FPM match encryption filter configuration mode, use the match encrypted command in class-map configuration mode. This mode enables you to enter encrypted filter-related information like the cipher key cipher value, and filter hash.


Note
The encrypted filter contents are not stored in the class map until the exit or endcommandis entered. When you exit from the encrypted filter submode without entering all the mandatory parameters, an error message is printed before exiting the submode. The cipher key, cipher value, and filter hash are the mandatory values. A filter is not configured in this case.

TCDF Packaging Support

TCDFs are FPM filters in XML format. Each TCDF file is designed to filter for a single individual worm or virus. TCDF packaging support provides packages containing at least one or more worm or virus filters and efficiently updates FPM filters as threat characteristics change. When FPM filters are updated, all systems in a network are automatically updated. This behavior reduces the amount of router configuration needed to deploy FRM filters.

To access TCDF packages, configure the router using the time-range command to periodically check for package updates. At the specified time, the router connects to the server containing the FPM packages to request the latest version. When the router gets feedback from the server, it compares the FPM package version number from the server with the local FPM package version. If there is an updated package on the server, then the router downloads the package content, replaces the old package with the new package, and updates the local configuration.

Full Packet FPM Search Window Increase

FPM supports searching for patterns up to 256 bytes long anywhere within the entire packet. Also, the number of filters that can be configured per class map is 32. The additional filters can help offset adverse CPU performance that may occur if the "window" for pattern searching is increased. This will also allow FPM users to take advantage of the regular expressions (regex) strings used by Intrusion Prevention Systems (IPS) in their signatures.

Session-based Flexible Packet Matching

FPM works at its best when the filter information exists in all packets of a packet flow. However, if matching contents only exist in a limited number of packets (regex strings and strings in the payload), then FPM can only apply actions to these packets, and miss the other packets in the same packet flow, which are a sequence of packets with the same attributes.

With the introduction of Cisco IOS Release 15.1(3)T, FPM can now match every packet against the filters specified in the class map and pass the match result to consecutive packets of the same network session. If a filter matches with malicious content in the packet's protocol header or payload, then the required action is taken to resolve the problem.

The match class session command configures match criteria that identify a session containing packets of interest, which is then applied to all packets transmitted during the session. The packet-range and byte-range keywords are used to create a filter mechanism that increases the performance and matching accuracy of regex-based FPM class maps by classifying traffic that resides in the narrow packet number or byte ranges of each packet flow. If packets go beyond the classification window, then the packet flow can be identified as unknown and packet classification is terminated early to increase performance. For example, a specific application can be blocked efficiently by filtering all packets that belong to this application on a session. These packets are dropped without matching every individual packet with the filters, which improves the performance of a session.

These filters also reduce the number of false positives introduced by general regex-based approaches. For example, internet company messenger traffic can be classified with a string like intco, intcomsg, and ic. These strings are searched for in a packet's payload. These small strings can appear in the packet payload of any other applications, such as e-mail, and can introduce false positives. False positives can be avoided by specifying which regex is searched within which packet of a particular packet flow. See "Creating a Traffic Class for Flexible Packet Matching" for more information.

Once the match criteria are applied to packets belonging to the specific traffic class, these packets can be discarded by configuring the drop allcommand in a policy map. Packets match only on the packet flow entry of an FPM, and skip user-configured classification filters. See "Creating a Traffic Policy for Flexible Packet Matching" for more information.

A match class does not have to be applied exclusively for a regex-based filter. Any FPM filter can be used in the nested match class filter. For example, if the match class c1 has the filter match field TCP source-port eq 80, then the match class c1 session command takes the same action for the packets that follow the first matching packet.

How to Configure a Flexible Packet Matching Traffic Class and Traffic Policy

Creating a Traffic Class for Flexible Packet Matching


Note
If the PHDF protocol fields are referenced in the access-control classmap, the stack classmap is required in order to make FPM work properly
SUMMARY STEPS

1.    enable

2.    configure terminal

3.    load protocol location:filename

4.    class-map [type {stack | access-control}] class-map-name [match-all | match-any]

5.    description character-string

6.   match field protocol protocol-field {eq [mask] | neq | [mask] | gt | lt | range range | regex string} value [next next-protocol]

7.    match start {l2-start | l3-start} offset number size number {eq | neq | gt | lt | range range | regex string} {value [value2] | [string]}

8.    match class class-name [packet-range low high | byte-range low high] session

9.    exit

10.    exit

11.    show class-map [type {stack | access-control} | class-map-name]


DETAILED STEPS
  Command or Action Purpose
Step 1
enable


Example:

Router> enable

 

Enables privileged EXEC mode.

  • Enter your password if prompted.
 
Step 2
configure terminal


Example:

Router# configure terminal

 

Enters global configuration mode.

 
Step 3
load protocol location:filename


Example:

Router(config)# load protocol disk2:udp.phdf

 

(Optional) Loads a PHDF onto a router.

  • The specified location must be local to the router.
Note    If a PHDF is not loaded, only the match start command can be used; that is, you cannot issue the match field command.
Note    For the ASR platform, PHDF files should be manually copied (through the load protocol command) to the active and standby route processor (RP) file systems.
 
Step 4
class-map [type {stack | access-control}] class-map-name [match-all | match-any]


Example:

Router(config)# class-map type access-control c1

 

Creates a class map to be used for matching packets to a specified class and enters class-map configuration mode.

  • type stack -- Enables FPM to determine the correct protocol stack in which to examine.
  • type access-control -- Determines the exact pattern to look for in the protocol stack of interest.
  • class-map-name -- Can be a maximum of 40 alphanumeric characters.
  • If match-all or match-anyor are not specified, traffic must match all the match criterion to be classified as part of the traffic class.
 
Step 5
description character-string


Example:

Router(config-cmap)# description "match on slammer packets"

 

(Optional) Adds a description to the class map.

 
Step 6
match field protocol protocol-field {eq [mask] | neq | [mask] | gt | lt | range range | regex string} value [next next-protocol]


Example:

Router(config-cmap)# match field udp dest-port eq 0x59A

 

(Optional) Configures the match criteria for a class map on the basis of the fields defined in the PHDFs.

  • The next next-protocol keyword-argument pair is available only after configuring the class-map type stack command.
 
Step 7
match start {l2-start | l3-start} offset number size number {eq | neq | gt | lt | range range | regex string} {value [value2] | [string]}


Example:

Router(config-cmap)# match start l3-start offset 224 size 4 eq 0x4011010

 

(Optional) Configures the match criteria for a class map on the basis of the datagram header (Layer 2) or the network header (Layer 3).

 
Step 8
match class class-name [packet-range low high | byte-range low high] session


Example:

Router(config-cmap)# match class c2 packet-range 1 5 session

 

(Optional) Configures match criteria for a class map that identifies a session (flow) containing packets of interest, which is then applied to all packets transmitted during the session.

The packet-range and byte-range keywords create a filter mechanism that increases the performance and matching accuracy of regex-based FPM class maps by classifying traffic that resides in the narrow packet number or packet byte ranges of each packet flow.

When the session keyword is used with the class-name argument, the classification results are preserved for the subsequent packets of the same packet session.

When the session keyword is used with the packet-range or byte-range keywords, the classification results are preserved for the specified packets or bytes of the same packet session.

 
Step 9
exit


Example:

Router(config-cmap)# exit

 

Exits class-map configuration mode.

 
Step 10
exit


Example:

Router(config)# exit

 

Exits global configuration mode.

 
Step 11
show class-map [type {stack | access-control} | class-map-name]


Example:

Router# show class-map type access-control slammer

 

(Optional) Displays configured FPM class maps.

 

Creating a Traffic Policy for Flexible Packet Matching

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    policy-map type access-control policy-map-name

4.    description character-string

5.    class class-name insert-before class-name

6.    drop [all]

7.    log [all]

8.    service-policy policy-map-name

9.    exit

10.    interface type number

11.    service-policy type access-control {input | output} policy-map-name

12.    exit

13.    exit

14.    show policy-map [type access-control | interface type number | input | output]


DETAILED STEPS
  Command or Action Purpose
Step 1
enable


Example:

Router> enable

 

Enables privileged EXEC mode.

  • Enter your password if prompted.
 
Step 2
configure terminal


Example:

Router# configure terminal

 

Enters global configuration mode.

 
Step 3
policy-map type access-control policy-map-name


Example:

Router(config)# policy-map type access-control fpm-udp-policy

 

Creates or modifies a policy map that can be attached to one or more interfaces to specify a service policy, and enters policy-map configuration mode.

 
Step 4
description character-string


Example:

Router(config-pmap)# description "policy for UDP based attacks"

 

(Optional) Adds a description to the policy map.

 
Step 5
class class-name insert-before class-name


Example:

Router(config-pmap)# class slammer

 

Specifies the name of a predefined traffic class, which was configured with the class-map command. The class command also classifies traffic to the traffic policy and enters policy-map class configuration mode.

  • The insert-before class-name keyword and argument adds a class map to any location within the policy map. If this option is not issued, the class map is appended to the end of the policy map.
 
Step 6
drop [all]


Example:

Router(config-pmap-c)# drop all

 

(Optional) Configures a traffic class to discard packets belonging to a specific class.

The all keyword is used to discard the entire stream of packets belonging to the traffic class.

If this command is issued, note the following restrictions:

  • Discarding packets is the only action that can be configured in a traffic class.
  • When a traffic class is configured with the drop command, a "child" (nested) policy cannot be configured for this specific traffic class through the service policy command.
  • Discarding packets cannot be configured for the default class specified via the class class-default command.
  • If the drop allcommand is specified, then this command can only be associated with a class map type access-control command.
 
Step 7
log [all]


Example:

Router(config-pmap-c)# log all

 

(Optional) Generates log messages for the traffic class.

The all keyword is used to log the entire stream of discarded packets belonging to the traffic class. This keyword is only available for a class map that is created with the class-map type access-control command.

 
Step 8
service-policy policy-map-name


Example:

Router(config-pmap-c)# service policy fpm-udp-policy

 

Creates hierarchical service policies.

 
Step 9
exit


Example:

Router(config-pmap-c)# exit



Example:

Router(config-pmap)# exit

 

Exits policy-map class configuration mode and policy-map configuration mode.

 
Step 10
interface type number


Example:

Router(config)# interface gigabitEthernet 0/1

 

Configures an interface type and enters interface configuration mode.

 
Step 11
service-policy type access-control {input | output} policy-map-name


Example:

Router(config-if)# service-policy type access-control input fpm-policy

 

Specifies the type and the name of the traffic policy to be attached to the input or output direction of an interface.

 
Step 12
exit


Example:

Router(config-if)# exit

 

Exits interface configuration mode.

 
Step 13
exit


Example:

Router(config)# exit

 

Exits global configuration mode.

 
Step 14
show policy-map [type access-control | interface type number | input | output]


Example:

Router# show policy-map type access-control interface gigabitethernet 0/1

 

(Optional) Verifies the FPM configuration.

Note    Once a traffic policy is created for FPM, a matched packet can be copied or redirected to a different destination interface.
 

Copying a Matched Packet To a Different Destination Interface

Perform this task to configure a traffic class to copy packets belonging to a specific class to a different destination interface.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    policy-map type access-control policy-map-name

4.    description character-string

5.    class class-name insert-before class-name

6.    copy interface type number

7.    service-policy policy-map-name

8.    exit

9.    interface type number

10.    service-policy type access-control {input | output} policy-map-name

11.    exit

12.    exit

13.    show policy-map type access-control [interface type number] [input | output]


DETAILED STEPS
  Command or Action Purpose
Step 1
enable


Example:

Router> enable

 

Enables privileged EXEC mode.

  • Enter your password if prompted.
 
Step 2
configure terminal


Example:

Router# configure terminal

 

Enters global configuration mode.

 
Step 3
policy-map type access-control policy-map-name


Example:

Router(config)# policy-map type access-control fpm-udp-policy

 

Creates or modifies a policy map that can be attached to one or more interfaces to specify a service policy and enters policy-map configuration mode.

 
Step 4
description character-string


Example:

Router(config-pmap)# description "policy for UDP based attacks"

 

(Optional) Adds a description to the policy map.

 
Step 5
class class-name insert-before class-name


Example:

Router(config-pmap)# class cmtest

 

Specifies the name of a predefined traffic class, which was configured with the class-map command, used to classify traffic to the traffic policy.

  • insert-before class-name --Adds a class map to any location within the policy map. If this option is not issued, the class map is appended to the end of the policy map.
 
Step 6
copy interface type number


Example:

Router(config-pmap-c)# copy interface FastEthernet 4/15

 

(Optional) Configures a traffic class to copy packets belonging to a specific class to a different destination interface.

If this command is issued, note the following restrictions:

  • This command cannot be used with drop or redirect interface command.
  • This command cannot be configured with a service policy for a stack class.
  • The packets can only be copied to the following interfaces: Ethernet, Fast Ethernet, Gigabit Ethernet, and Ten Gigabit Ethernet.
 
Step 7
service-policy policy-map-name


Example:

Router(config-pmap-c)# service policy fpm-udp-policy

 

Creates hierarchical service policies.

 
Step 8
exit


Example:

Router(config-pmap-c)# exit



Example:

Router(config-pmap)# exit

 

Exits policy-map class configuration mode and policy-map configuration mode.

 
Step 9
interface type number


Example:

Router(config)# interface gigabitEthernet 0/1

 

Configures an interface type and enters interface configuration mode.

 
Step 10
service-policy type access-control {input | output} policy-map-name


Example:

Router(config-if)# service-policy type access-control input fpm-policy

 

Specifies the type and the name of the traffic policy to be attached to the input or output direction of an interface.

 
Step 11
exit


Example:

Router(config-if)# exit

 

Exits interface configuration mode.

 
Step 12
exit


Example:

Router(config)# exit

 

Exits global configuration mode.

 
Step 13
show policy-map type access-control [interface type number] [input | output]


Example:

Router# show policy-map type access-control interface gigabit 0/1

 

(Optional) Verifies the FPM configuration.

 

Redirecting a Matched Packet To a Different Destination Interface

Perform this task to configure a traffic class to redirect packets belonging to a specific class to a different destination.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    policy-map type access-control policy-map-name

4.    description character-string

5.    class class-name insert-before class-name

6.    redirect interface type number

7.    service-policy policy-map-name

8.    exit

9.    interface type number

10.    service-policy type access-control {input | output} policy-map-name

11.    exit

12.    exit

13.    show policy-map type access-control [interface type number][input | output]]


DETAILED STEPS
  Command or Action Purpose
Step 1
enable


Example:

Router> enable

 

Enables privileged EXEC mode.

  • Enter your password if prompted.
 
Step 2
configure terminal


Example:

Router# configure terminal

 

Enters global configuration mode.

 
Step 3
policy-map type access-control policy-map-name


Example:

Router(config)# policy-map type access-control fpm-udp policy

 

Creates or modifies a policy map that can be attached to one or more interfaces to specify a service policy and enters policy-map configuration mode.

 
Step 4
description character-string


Example:

Router(config-pmap)# description "policy for UDP based attacks"

 

(Optional) Adds a description to the policy map.

 
Step 5
class class-name insert-before class-name


Example:

Router(config-pmap)# class cmtest

 

Specifies the name of a predefined traffic class, which was configured with the class-map command, used to classify traffic to the traffic policy.

  • insert-before class-name --Adds a class map to any location within the policy map. If this option is not issued, the class map is appended to the end of the policy map.
 
Step 6
redirect interface type number


Example:

Router(config-pmap-c)# redirect interface FastEthernet 4/15

 

(Optional) Configures a traffic class to redirect packets belonging to a specific class to a different destination interface.

If this command is issued, note the following restrictions:

  • This command cannot be using with the drop or copy interface command.
  • This command cannot be configured with a service policy for a stack class.
  • The packets can only be copied to the following interfaces: Ethernet, Fast Ethernet, Gigabit Ethernet, and Ten Gigabit Ethernet.
 
Step 7
service-policy policy-map-name


Example:

Router(config-pmap-c)# service policy fpm-udp-policy

 

Creates hierarchical service policies.

 
Step 8
exit


Example:

Router(config-pmap-c)# exit



Example:

Router(config-pmap)# exit

 

Exits policy-map class configuration mode and policy-map configuration mode.

 
Step 9
interface type number


Example:

Router(config)# interface gigabitEthernet 0/1

 

Configures an interface type and enters interface configuration mode.

 
Step 10
service-policy type access-control {input | output} policy-map-name


Example:

Router(config-if)# service-policy type access-control input fpm-policy

 

Specifies the type and the name of the traffic policy to be attached to the input or output direction of an interface.

 
Step 11
exit


Example:

Router(config-if)# exit

 

Exits interface configuration mode.

 
Step 12
exit


Example:

Router(config)# exit

 

Exits global configuration mode.

 
Step 13
show policy-map type access-control [interface type number][input | output]]


Example:

Router# show policy-map type access-control interface gigabit 0/1

 

(Optional) Verifies the FPM configuration.

 

Configuring Packaging Support for Flexible Packet Matching

Perform this task to configure FPM packaging support.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    fpm package-info

4.    time-range time-setting

5.    host ip-address

6.    local-path memory-option

7.    remote-path path-name

8.    exit

9.    fpm package-group fpm-group-name

10.    package fpm-package-name

11.    action log

12.    exit

13.    auto-load

14.    end


DETAILED STEPS
  Command or Action Purpose
Step 1
enable


Example:

Router> enable

 

Enables privileged EXEC mode.

  • Enter your password if prompted.
 
Step 2
configure terminal


Example:

Router# configure terminal

 

Enters global configuration mode.

 
Step 3
fpm package-info


Example:

Router(config)# fpm package-info

 

Enters FPM configuration mode.

 
Step 4
time-range time-setting


Example:

Router(config-fpm-pak-info)# time-range weekly

 

Specifies the time interval to check for new FPM packages.

 
Step 5
host ip-address


Example:

Router(config-fpm-pak-info)# host 10.0.0.1

 

Specifies the location from where FPM package updates are downloaded.

 
Step 6
local-path memory-option


Example:

Router(config-fpm-pak-info)# local-path flash:

 

Specifies where the FPM packages are stored locally.

 
Step 7
remote-path path-name


Example:

Router(config-fpm-pak-info)# remote-path fpm-security

 

Specifies the location of the FPM packages on the FPM server.

 
Step 8
exit


Example:

Router(config-fpm-pak-info)# exit

 

Exits FPM configuration.

 
Step 9
fpm package-group fpm-group-name


Example:

Router(config)# fpm package-group fpm-update

 

Specifies an FPM group and enters FPM group definition mode.

 
Step 10
package fpm-package-name


Example:

Router(config-fpm-pak-grp)# package fpm-group-44

 

Specifies an FPM package and enters FPM package definition mode.

 
Step 11
action log


Example:

Router(config-fpm-pak-grp-pak)# action log

 

Enables logging for this FPM package.

 
Step 12
exit


Example:

Router(config-fpm-pak-grp-pak)# exit

 

Exits FPM package mode and enters FPM group definition configuration mode.

 
Step 13
auto-load


Example:

Router(config-fpm-pak-grp)# auto-load

 

Enable automatic loading of the FPM package.

 
Step 14
end


Example:

Router(config-fpm-pak-grp)# end

 

Exits FPM configuration mode and enters privileged EXEC mode.

 

Configuring eTCDF Through the Command-Line Interface

If you have access to an encrypted traffic classification definition file (eTCDF) or if you know valid values to configure encrypted FPM filters, you can configure the same eTCDF through the command-line interface instead of using the preferred method of loading the eTCDF on the router. You can copy the values from the eTCDF by opening the eTCDF in any text editor.

Perform this task to configure eTCDF through the command-line interface.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    class-map type access-control [match-all | match-any] class-map-name

4.    match encrypted

5.    algorithm algorithm

6.    cipherkey key-name

7.    ciphervalue contents

8.    filter-hash hash-value

9.    filter-id id-value

10.    filter-version version

11.    end


DETAILED STEPS
  Command or Action Purpose
Step 1
enable


Example:

Router> enable

 

Enables privileged EXEC mode.

  • Enter your password if prompted.
 
Step 2
configure terminal


Example:

Router# configure terminal

 

Enters global configuration mode.

 
Step 3
class-map type access-control [match-all | match-any] class-map-name


Example:

Router(config)# class-map type access-control match-all class1

 

Creates a class map to be used for matching packets to a specified class and enters class-map configuration mode.

 
Step 4
match encrypted


Example:

Router(config-cmap)# match encrypted

 

Configures the match criteria for a class map on the basis of encrypted Flexible Packet Matching (FPM) filters and enters the FPM match encryption filter configuration mode.

 
Step 5
algorithm algorithm


Example:

Router(c-map-match-enc-config)# algorithm aes256cbc

 

Specifies the algorithm to be used for decrypting the filters.

 
Step 6
cipherkey key-name


Example:

Router(c-map-match-enc-config)# cipherkey realm-abc.sym

 

Specifies the symmetric key-name that is used to decrypt the filter.

 
Step 7
ciphervalue contents


Example:

Router(c-map-match-enc-config)# ciphervalue #2bcXhFL8Ld1v+DqU+dnxgmONCxl4JrYfcLl95xg



Example:

ET0b2B1z0sjoCkozE8YxiH/SXL+eG2wf3ogaA7/Fh



Example:

awIH7OF3tUcS5Jwim/u95Xlzh2RLNw819tuIBCdorV



Example:

Cu0ZzWCF3vqwpGQzaxtSE4sFgPAvSE2LxZc/VT22



Example:

F7EQKBhRo=#

 

Specifies the encrypted filter contents.

 
Step 8
filter-hash hash-value


Example:

Router(c-map-match-enc-config)# filter-hash AABBCCDD11223344

 

Specifies the hash for verification and validation of decrypted contents.

 
Step 9
filter-id id-value


Example:

Router(c-map-match-enc-config)# filter-id id2

 

Specifies a filter-level ID for encrypted filters.

 
Step 10
filter-version version


Example:

Router(c-map-match-enc-config)# filter-version v1

 

Specifies the filter-level version value for the encrypted filter.

 
Step 11
end


Example:

Router(c-map-match-enc-config)# end

 

Exits FPM match encryption filter configuration mode and returns to privileged EXEC mode.

 

Configuration Examples for Flexible Packet Matching

Example: Configuring FPM for Slammer Packets

The following example shows how to define FPM traffic classes for slammer packets (UDP port 1434). The match criteria defined within the class maps is for slammer packets with an IP length not to exceed 404 bytes, UDP port 1434, and pattern 0x4011010 at 224 bytes from start of IP header. This example also shows how to define the service policy "fpm-policy" and apply it to the Gigabit Ethernet interface. Show commands have been issued to verify the FPM configuration. (Note that PHDFs are not displayed in show output because they are in XML format.)

Router(config)# load protocol disk2:ip.phdf
Router(config)# load protocol disk2:udp.phdf
Router(config)# class-map type stack match-all ip-udp
Router(config-cmap)# description "match UDP over IP packets"
Router(config-cmap)# match field ip protocol eq 0x11 next udp
Router(config)# class-map type access-control match-all slammer
Router(config-cmap)# description "match on slammer packets"
Router(config-cmap)# match field udp dest-port eq 0x59A
Router(config-cmap)# match field ip length gt 0x194
Router(config-cmap)# match start l3-start offset 224 size 4 eq 0x4011010
Router(config)# policy-map type access-control fpm-udp-policy
Router(config-pmap)# description "policy for UDP based attacks"
Router(config-pmap)# class slammer
Router(config-pmap-c)# drop
Router(config)# policy-map type access-control fpm-policy
Router(config-pmap)# description "drop worms and malicious attacks"
Router(config-pmap)# class ip-udp
Router(config-pmap-c)# service-policy fpm-udp-policy
Router(config)# interface gigabitEthernet 0/1
Router(config-if)# service-policy type access-control input fpm-policy
Router# show policy-map type access-control interface gigabit 0/1
GigabitEthernet0/1
Service-policy access-control input: fpm-policy
Class-map: ip-udp (match-all)
0 packets, 0 bytes
3 minute offered rate 0 bps
Match: field IP protocol eq 0x11 next UDP
Service-policy access-control : fpm-udp-policy
Class-map: slammer (match-all)
0 packets, 0 bytes
3 minute offered rate 0 bps, drop rate 0 bps
Match: field UDP dest-port eq 0x59A
Match: field IP length eq 0x194
Match: start l3-start offset 224 size 4 eq 0x4011010
drop
Class-map: class-default (match-any)
0 packets, 0 bytes
3 minute offered rate 0 bps, drop rate 0 bps
Match: any
Class-map: class-default (match-any)
0 packets, 0 bytes
3 minute offered rate 0 bps, drop rate 0 bps
Match: any
Router# show protocol phdf ip
Protocol ID: 1
Protocol name: IP
Description: Definition-for-the-IP-protocol
Original file name: disk2:ip.phdf
Header length: 20
Constraint(s):
Total number of fields: 12
Field id: 0, version, IP-version
Fixed offset. offset 0
Constant length. Length: 4
Field id: 1, ihl, IP-Header-Length
Fixed offset. offset 4
Constant length. Length: 4
Field id: 2, tos, IP-Type-of-Service
Fixed offset. offset 8
Constant length. Length: 8
Field id: 3, length, IP-Total-Length
Fixed offset. offset 16
Constant length. Length: 16
Field id: 4, identification, IP-Identification
Fixed offset. offset 32
Constant length. Length: 16
Field id: 5, flags, IP-Fragmentation-Flags
Fixed offset. offset 48
Constant length. Length: 3
Field id: 6, fragment-offset, IP-Fragmentation-Offset
Fixed offset. offset 51
Constant length. Length: l3
Field id: 7, ttl, Definition-for-the-IP-TTL
Fixed offset. offset 64
Constant length. Length: 8
Field id: 8, protocol, IP-Protocol
Fixed offset. offset 72
Constant length. Length: 8
Field id: 9, checksum, IP-Header-Checksum
Fixed offset. offset 80
Constant length. Length: 16
Field id: 10, source-addr, IP-Source-Address
Fixed offset. offset 96
Constant length. Length: 32
Field id: 11, dest-addr, IP-Destination-Address
Fixed offset. offset 128
Constant length. Length: 32
Router# show protocol phdf udp
Protocol ID: 3
Protocol name: UDP
Description: UDP-Protocol
Original file name: disk2:udp.phdf
Header length: 8
Constraint(s):
Total number of fields: 4
Field id: 0, source-port, UDP-Source-Port
Fixed offset. offset 0
Constant length. Length: 16
Field id: 1, dest-port, UDP-Destination-Port
Fixed offset. offset 16
Constant length. Length: 16
Field id: 2, length, UDP-Length
Fixed offset. offset 32
Constant length. Length: 16
Field id: 3, checksum, UDP-Checksum
Fixed offset. offset 48
Constant length. Length: 16

Example: Configuring FPM for Blaster Packets

The following example shows how to configure FPM for blaster packets. The class map contains the following match criteria: TCP port 135, 4444 or UDP port 69; and pattern 0x0030 at 3 bytes from the start of the IP header.

Router(config)# load protocol disk2:ip.phdf
Router(config)# load protocol disk2:tcp.phdf
Router(config)# load protocol disk2:udp.phdf
 
Router(config)# class-map type stack match-all ip-tcp
Router(config-cmap)# match field ip protocol eq 0x6 next tcp
Router(config)# class-map type stack match-all ip-udp
Router(config-cmap)# match field ip protocol eq 0x11 next udp
Router(config)# class-map type access-control match-all blaster1
Router(config-cmap)# match field tcp dest-port eq 135
Router(config-cmap)# match start l3-start offset 3 size 2 eq 0x0030
Router(config)# class-map type access-control match-all blaster2
Router(config-cmap)# match field tcp dest-port eq 4444
Router(config-cmap)# match start l3-start offset 3 size 2 eq 0x0030
Router(config)# class-map type access-control match-all blaster3
Router(config-cmap)# match field udp dest-port eq 69
Router(config-cmap)# match start l3-start offset 3 size 2 eq 0x0030
Router(config)# policy-map type access-control fpm-tcp-policy
Router(config-pmap)# class blaster1
Router(config-pmap-c)# drop
Router(config-pmap-c)# class blaster2
Router(config-pmap-c)# drop
Router(config)# policy-map type access-control fpm-udp-policy
Router(config-pmap)# class blaster3
Router(config-pmap-c)# drop
Router(config)# policy-map type access-control fpm-policy
Router(config-pmap)# class ip-tcp
Router(config-pmap-c)# service-policy fpm-tcp-policy
Router(config-pmap)# class ip-udp
Router(config-pmap-c)# service-policy fpm-udp-policy
Router(config)# interface gigabitEthernet 0/1
Router(config-if)# service-policy type access-control input fpm-policy

Example: Configuring FPM for MyDoom Packets

The following example shows how to configure FPM for MyDoom packets. The match criteria is as follows:

  • 90 > IP length > 44
  • pattern 0x47455420 at 40 bytes from start of IP header

or

  • IP length > 44
  • pattern 0x6d3a3830 at 48 bytes from start of IP header
  • pattern 0x47455420 at 40 bytes from start of IP header 
Router(config)# load protocol disk2:ip.phdf
Router(config)# load protocol disk2:tcp.phdf
Router(config)# class-map type stack match-all ip-tcp
Router(config-cmap)# match field ip protocol eq 0x6 next tcp
Router(config)# class-map type access-control match-all mydoom1
Router(config-cmap)# match field ip length gt 44
Router(config-cmap)# match field ip length lt 90
Router(config-cmap)# match start l3-start offset 40 size 4 eq 0x47455420
Router(config)# class-map type access-control match-all mydoom2
Router(config-cmap)# match field ip length gt 44
Router(config-cmap)# match start l3-start offset 40 size 4 eq 0x47455420
Router(config-cmap)# match start l3-start offset 48 size 4 eq 0x6d3a3830 
Router(config)# policy-map type access-control fpm-tcp-policy
Router(config-pmap)# class mydoom1
Router(config-pmap-c)# drop
Router(config-pmap-c)# class mydoom2
Router(config-pmap-c)# drop
Router(config)# policy-map type access-control fpm-policy
Router(config-pmap)# class ip-tcp
Router(config-pmap-c)# service-policy fpm-tcp-policy
Router(config)# interface gigabitEthernet 0/1
Router(config-if)# service-policy type access-control input fpm-policy

Example: Configuring and Verifying FPM on ASR Platform

The following example shows how to configure FPM on the ASR platform.

load protocol bootflash:ip.phdf
load protocol bootflash:tcp.phdf
class-map type stack match-all ip-tcp
 match field IP protocol eq 6 next TCP
class-map type access-control match-all test-class
 match field TCP dest-port gt 10
 match start l3-start offset 40 size 32 regex "ABCD"
policy-map type access-control child
 class test-class
  drop
policy-map type access-control parent
 class ip-tcp
  service-policy child
interface GigabitEthernet0/3/0
 ip address 10.1.1.1 255.0.0.0
 service-policy type access-control input parent

In the following sample output, all TCP packets are seen under the class map named ip_tcp and all packets matching the specific pattern are seen under the class map named test_class. TCP packets without the specific pattern are seen under the child policy named class-default, while all non-TCP packets are seen under the parent policy named class-default. (The counter is 0 in this example.)

Router# show policy-map type access-control interface gig0/3/0
GigabitEthernet0/3/0
 Service-policy access-control input: parent
  Class-map: ip_tcp (match-all)
  2024995578 packets, 170099628552 bytes
  5 minute offered rate 775915000 bps
  Match: field IP version eq 4
  Match: field IP ihl eq 5
  Match: field IP protocol eq 6 next TCP
 Service-policy access-control : child
 Class-map: test_class (match-all)
  1598134279 packets, 134243279436 bytes
  5 minute offered rate 771012000 bps, drop rate 771012000 bps
  Match: field TCP dest-port gt 10
  Match: start l3-start offset 40 size 32 regex "ABCD"
 drop
 Class-map: class-default (match-any)
  426861294 packets, 35856348696 bytes
  5 minute offered rate 4846000 bps, drop rate 0 bps
  Match: any
 Class-map: class-default (match-any)
  0 packets, 0 bytes
  5 minute offered rate 0 bps, drop rate 0 bps
  Match: any
Router#

Example: Configuring Session-based FPM

The following example shows how to configure a class map and policy map to specify the protocol stack class, the match criteria and action to take, and a combination of classes using session-based (flow-based) and nonsession-based actions. The drop all command is associated with the action to be taken on the policy.

Router(config)# class-map type access-control match-all my-HTTP
Router(config-cm)# match field tcp destport eq 8080
Router(config-cm)# match start tcp payload-start offset 20 size 10 regex "GET"
Router(config)# class-map type access-control match-all my-FTP
Router(config-cmap)# match field tcp destport eq 21
Router(config)# class-map type access-control match all class1
Router(config-cmap)# match class my-HTTP session
Router(config-cmap)# match start tcp payload-start offset 40 size 20 regex "abc.*def"
Router(config)# policy-map type access-control my_http_policy
Router(config-pmap)# class class1
Router(config-pmap-c)# drop all
Router(config)# interface gigabitEthernet 0/1
Router(config-if)# service-policy type access-control input my_http_policy

Example: Configuring Session-based FPM with a Filter for Increased Performance and Accuracy

The following example shows how to configure a class map and policy map to specify the protocol stack class, the match criteria and action to take, and a combination of classes using session-based (flow-based) and nonsession-based actions. However, this example uses the match class packet-range command, which acts as a filter mechanism to increases the performance and matching accuracy of the regex-based FPM class map.

Router(config)# load disk2:ip.phdf
Router(config)# load protocol disk2:tcp.phdf
Router(config)# class-map type stack match-all ip_tcp
Router(config-cmap)# description "match TCP over IP packets"
Router(config-cmap)# match field ip protocol eq 6 next tcp
Router(config)# class-map type access-control match-all WM
Router(config-cmap) # match start tcp payload-start offset 20 size 20 regex
".*(WEBCO|WMSG|WPNS).......[LWT].*\xc0\x80"
Router(config)# class-map type access-control match-all wtube
Router(config-cmap) # match start tcp payload-start offset 20 size 20 regex
".*GET\x20.*HTTP\x2f(0\.9|1\.0|1\.1)\x0d\x0aHost:\x20webtube.com\x0d\x0a"
Router(config)# class-map type access-control match-all doom
Router(config-cmap) # match start tcp payload-start offset 20 size 20 string virus
Router(config)# class-map type access-control match-all class_webco
Router(config-cmap)# match class WM session
Router(config-cmap)# match field ip length eq 0x194
Router(config-cmap)# match start network-start offset 224 size 4 eq 0x4011010
Router(config)# class-map type access-control match-all class_webtube
Router(config-cmap)# match class wtube packet-range 1 5 session
Router(config-cmap)# match class doom session
Router(config-cmap)# match field ip length eq 0x194
Router(config-cmap)# match start network-start offset 224 size 4 eq 0x4011010
Router(config)# policy-map type access-control my_policy
Router(config-pmap)# class class_webco
Router(config-pmap-c)# log
Router(config)# policy-map type access-control my_policy
Router(config-pmap)# class class_webtube
Router(config-pmap-c)# drop all
Router(config)# policy-map type access-control P1
Router(config-pmap)# class ip_tcp
Router(config-pmap-c)# service-policy my_policy
Router(config)# interface gigabitEthernet 0/1
Router(config-if)# service-policy type access-control input P1

Example: Verifying FPM Package Support

The following example shows how to verify FPM Package support.

Router# show fpm package-info
 fpm package-info
  host 10.0.0.1
  remote-path fpm-group/
  local-path archive/
  user cisco
  password 
  protocol 
  time-range weekly
Router# show fpm package-group
 group name: fpm-weekly-update
  auto-load
  fpm package: fpm-package-45
  fpm package: fpm-group-secure
   package action: log

Additional References

Related Documents

Related Topic

Document Title

Cisco IOS commands

Cisco IOS Master Commands List, All Releases

Security commands

Cisco IOS Security Command Reference

Configuring FPM using traffic classification definition files.

"Flexible Packet Matching XML Configuration" module in the Cisco IOS Security Configuration Guide: Securing the Data Plane

Complete suite of quality of service (QoS) commands

Cisco IOS Quality of Service Solutions Command Reference

Standards

Standards

Title

None

--

MIBs

MIBs

MIBs Link

None

To locate and download MIBs for selected platforms, Cisco software releases, and feature sets, use Cisco MIB Locator found at the following URL:

http://www.cisco.com/go/mibs

RFCs

RFCs

Title

None

--

Technical Assistance

Description

Link

The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

http://www.cisco.com/cisco/web/support/index.html

Feature Information for Flexible Packet Matching

The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.

Table 1 Feature Information for Flexible Packet Matching

Feature Name

Releases

Feature Information

Flexible Packet Matching

12.4(4)T 12.2(18)ZY

FPM is a packet classification feature that allows users to define one or more classes of network traffic by pairing a set of standard matching operators with user-defined protocol header fields.

In Cisco IOS Release 12.2(18)ZY, FPM was implemented on the Catalyst 6500 series of switches equipped with the PISA.

The following commands were introduced or modified:

class , class-map, copy interface, debug fpm event, description, load protocol, match field, match start, policy-map, service-policy, show class-map, show policy-map interface, redirect interface, show protocol phdf.

FPM Full Packet Filtering

12.4(15)T

In Cisco IOS Release 12.4(15)T, FPM supports searching for patterns up to 56 bytes long anywhere within the entire packet. Prior to 12.4(15)T, FPM only supported searching for patterns up to 32 bytes long within the first 256 bytes of the packet.

Enhance FPM Search Window Size to 128 Bytes

12.2(18)ZYA

FPM supports searching for patterns up to 128 bytes long anywhere within the entire packet. Also, the number of filters that can be configured per class map has increased from 8 to 32. The additional filters can help offset adverse CPU performance that may occur if the "window" for pattern searching is increased. (However, some optimizations for better performance are possible with match-any type of class maps that have filters starting at same the same offset and the same size.)

FPM Copy or Redirect Matched Packets

12.2(18)ZYA1

When a match of the policy is found, the packet can be redirected to a different destination or a copy of the packet can be sent to a different destination.

This is possible with the copy interface and redirect interface commands introduced in this release.

The actions supported in this release are copy, copy and log, drop, drop and log, log, redirect, redirect and log.

FPM--Packaging, eTCDF, and Full Packet Search Enhancements

15.0(1)M

FPM--Packaging, eTCDF and Full Packet Search Enhancements provide preconfigured FPM filters written in XML format which can be directly loaded onto a router.

The following commands were introduced or modified: algorithm, cipherkey, ciphervalue, filter-hash, filter-id, filter-version, fpm package-group, fpm package-info, show fpm-package-group, match encrypted, show fpm package-info.

Session-based Flexible Packet Matching

15.1(3)T

With the introduction of Cisco IOS Release 15.1(3)T, FPM can now match every packet against the filters specified in the class map and passes the match result to consecutive packets of the same network session. If a filter matches with malicious content in the packet's protocol header or payload, then the required action is taken to resolve the problem.

The following commands were introduced or modified: match class session, drop, log.

Cisco and the Cisco logo are trademarks or registered trademarks of Cisco and/or its affiliates in the U.S. and other countries. To view a list of Cisco trademarks, go to this URL: www.cisco.com/go/trademarks. Third-party trademarks mentioned are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company. (1110R)

Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be actual addresses and phone numbers. Any examples, command display output, network topology diagrams, and other figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses or phone numbers in illustrative content is unintentional and coincidental.

1 Send ICMP unreachable is currently not supported on the Supervisor Engine 32 PISA.
© 2012 Cisco Systems, Inc. All rights reserved.