Security Configuration Guide: Flexible Packet Matching Cisco IOS Release 15.1M&T

Flexible Packet Matching

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 for Flexible Packet Matching" section.

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

Contents

•Restrictions for Flexible Packet Matching

•Information About Flexible Packet Matching

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

•Configuration Examples for Flexible Packet Matching

•Additional References

•Feature Information for Flexible Packet Matching

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

•Traffic Classification Definition Files for the Flexible Packet Matching XML Configuration

•FPM on the Catalyst 6500 Equipped with PISA Overview

•Encrypted TCDF Support

•TCDF Packaging Support

•Full Packet FPM Search Window Increase

•Session-based 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 via 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 "How to Configure a Flexible Packet Matching Traffic Class and Traffic Policy."

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 end command is 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" section 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 all command 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" section 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

•Creating a Traffic Policy for Flexible Packet Matching

•Configuring Packaging Support for Flexible Packet Matching

•Configuring eTCDF Through the Command-Line Interface

Creating a Traffic Class for Flexible Packet Matching

Perform this task to create an FPM traffic class; that is, create stateless packet classification criteria that, when used in conjunction with an appropriately defined policy, can mitigate network attacks.

Note If the PHDF protocol fields are referenced in the access-control class map, the stack class map 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 access-control | type stack} [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]

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

9. exit

10. exit

11. show class-map [type access-control [class-map-name]]

DETAILED STEPS

Troubleshooting Tips

To track all FPM events, issue the debug fpm event command.

The following is sample output from the debug fpm event command:

Router# debug fpm event

*Jun 21 09:22:21.607: policy-classification-inline(): matches class: class-default *Jun 21 
09:22:21.607: packet-access-control(): policy-map: fpm-policy, dir: input, match. retval: 
0x0, ip-flags: 0x80000000

What to Do Next

After you have defined at least one class map for your network, you must create a traffic policy and apply that policy to an interface as shown in the ""Creating a Traffic Policy for Flexible Packet Matching" section."

Creating a Traffic Policy for Flexible Packet Matching

Perform this task to create an FPM traffic policy and apply the policy to a given interface.

After you create a traffic policy for FPM, you can copy or redirect a matched packet to a different destination interface:

•"Copying a Matched Packet To a Different Destination Interface" section (optional)

•"Redirecting a Matched Packet To a Different Destination Interface" section (optional)

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

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

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

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-packet-name

11. action log

12. exit

13. auto-load

14. end

DETAILED STEPS

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 keyname

7. ciphervalue contents

8. filter-hash hash-value

9. filter-id id-value

10. filter-version version

11. end

DETAILED STEPS

Configuration Examples for Flexible Packet Matching

•Example: Configuring FPM for Slammer Packets

•Example: Configuring FPM for Blaster Packets

•Example: Configuring FPM for MyDoom Packets

•Example: Configuring and Verifying FPM on ASR Platform

•Example: Configuring Session-based FPM

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

•Example: Verifying FPM Package Support

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

Standards

MIBs

RFCs

Technical Assistance

Feature Information for Flexible Packet Matching

Table 1 lists the release history for this feature.

Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Note Table 1 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.

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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.

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