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IPv6 Snooping

Last Updated: August 6, 2012

The IPv6 snooping feature bundles several layer 2 IPv6 first-hop security features, including IPv6 neighbor discovery, IPv6 device tracking, and IPv6 address glean. IPv6 snooping operates at layer 2, or between layer 2 and layer 3, and provides IPv6 features with security and scalability.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and 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 module.

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.

Information About IPv6 Snooping

IPv6 Snooping

The IPv6 snooping feature bundles several layer 2 IPv6 first-hop security features, including IPv6 address glean, IPv6 device tracking, and IPv6 neighbor discovery. IPv6 snooping operates at layer 2, or between layer 2 and layer 3, and provides IPv6 features with security and scalability.

When IPv6 snooping is configured on a target (which vary depending on platform target support and may include device ports, switchports, layer 2 interfaces, layer 3 interfaces, and VLANs), capture instructions are downloaded to the hardware to redirect the neighbor discovery (ND) protocol and Dynamic Host Configuration Protocol (DHCP) for IPv6 traffic up to the switch integrated security features (SISF) infrastructure in the routing device. For ND traffic, messages such as NS; NA, RS, RA and REDIRECT are directed to SISF. For DHCP, UDP messages sourced from port 546 or 547 are redirected.

IPv6 snooping capture registers its "capture rules" to the classifier, which aggregates all rules from all features on a given target, and installs the corresponding ACL down into the platform-dependent modules. Upon receiving redirected traffic, the classifier calls all entry points from any registered feature (for the target on which the traffic is being received), including the IPv6 snooping entry point. The IPv6 snooping entry point is the last to be called, so any decision (such as drop) made by another feature supersedes the IPv6 snooping decision.

IPv6 Neighbor Discovery Inspection

IPv6 ND inspection learns and secures bindings for stateless autoconfiguration addresses in Layer 2 neighbor tables. IPv6 ND inspection analyzes ND messages in order to build a trusted binding table. IPv6 ND messages that do not have valid bindings are dropped.

IPv6 Global Policies

IPv6 global policies provide storage and access policy database services. IPv6 neighbor discovery (ND) inspection and the IPv6 Router Advertisement (RA) Guard are IPv6 global policies features. Every time an ND inspection or RA guard is configured globally, the policy attributes are stored in the software policy database. The policy is then applied to an interface, and the software policy database entry is updated to include this interface to which the policy is applied.

IPv6 ND Inspection

IPv6 ND inspection learns and secures bindings for stateless autoconfiguration addresses in Layer 2 neighbor tables. IPv6 ND inspection analyzes neighbor discovery messages in order to build a trusted binding table database, and IPv6 neighbor discovery messages that do not have valid bindings are dropped. A neighbor discovery message is considered trustworthy if its IPv6-to-MAC mapping is verifiable.

This feature mitigates some of the inherent vulnerabilities for the neighbor discovery mechanism, such as attacks on duplicate address detection (DAD), address resolution, device discovery, and the neighbor cache.

IPv6 Device Tracking

IPv6 device tracking provides IPv6 host liveness tracking so that a neighbor table can be immediately updated when an IPv6 host disappears.

IPv6 First-Hop Security Binding Table

A database table of IPv6 neighbors connected to the device is created from information sources such as Neighbor Discovery (ND) protocol snooping. This database, or binding, table is used by various IPv6 guard features to validate the link-layer address (LLA), the IPv4 or IPv6 address, and prefix binding of the neighbors to prevent spoofing and redirect attacks.

IPv6 Device Tracking

The IPv6 device tracking feature provides IPv6 host liveness tracking so that a neighbor table can be immediately updated when an IPv6 host disappears. The feature tracks the liveness of the neighbors connected through the Layer 2 device on regular basis in order to revoke network access privileges as they become inactive.

IPv6 Address Glean

The IPv6 address glean feature is the foundation for many other IPv6 features that depend on an accurate binding table. It inspects ND and DHCP messages on a link to glean addresses, and then populates the binding table with these addresses. This feature also enforces address ownership and limits the number of addresses any given node is allowed to claim.

The following figure shows how IPv6 address glean works.



How to Configure IPv6 Snooping

Configuring IPv6 Snooping

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    ipv6 snooping policy snooping-policy

4.   ipv6 snooping attach-policy snooping-policy


DETAILED STEPS
Step 1   enable


Example:
Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.
Step 2   configure terminal


Example:
Device# configure terminal

Enters global configuration mode.

Step 3   ipv6 snooping policy snooping-policy


Example:
Device(config)# ipv6 snooping policy policy1
Configures an IPv6 snooping policy named policy1 and enters IPv6 snooping configuration mode.
Step 4   ipv6 snooping attach-policy snooping-policy


Example:
Device(config-ipv6-snooping)# ipv6 snooping attach-policy policy1
Attaches the IPv6 snooping policy named policy1 to a target.

Configuring IPv6 Neighbor Discovery Inspection

Configuring IPv6 ND Inspection Globally
SUMMARY STEPS

1.    enable

2.    configure terminal

3.    ipv6 nd inspection policy policy-name

4.    drop-unsecure

5.    sec-level minimum value

6.    device-role {host | monitor | router}

7.    tracking {enable [reachable-lifetime {value | infinite}] | disable [stale-lifetime {value | infinite}]}

8.    trusted-port


DETAILED STEPS
 Command or ActionPurpose
Step 1
enable


Example:

Device> enable

 

Enables privileged EXEC mode.

  • Enter your password if prompted.
 
Step 2
configure terminal


Example:

Device# configure terminal

 

Enters global configuration mode.

 
Step 3
ipv6 nd inspection policy policy-name


Example:

Device(config)# ipv6 nd inspection policy policy1

 

Defines the ND inspection policy name and places the device in ND inspection policy configuration mode.

 
Step 4
drop-unsecure


Example:

Device(config-nd-inspection)# drop-unsecure

 

Drops messages with no options, invalid options, or an invalid signature.

 
Step 5
sec-level minimum value


Example:

Device(config-nd-inspection)# sec-level minimum 2

 

Specifies the minimum security level parameter value when cryptographically generated address (CGA) options are used.

 
Step 6
device-role {host | monitor | router}


Example:

Device(config-nd-inspection)# device-role monitor

 

Specifies the role of the device attached to the port.

 
Step 7
tracking {enable [reachable-lifetime {value | infinite}] | disable [stale-lifetime {value | infinite}]}


Example:

Device(config-nd-inspection)# tracking disable stale-lifetime infinite

 

Overrides the default tracking policy on a port.

 
Step 8
trusted-port


Example:

Device(config-nd-inspection)# trusted-port

 

Configures a port to become a trusted port.

 
Applying IPv6 ND Inspection on a Specified Interface
SUMMARY STEPS

1.    enable

2.    configure terminal

3.    interface type number

4.    ipv6 nd inspection [attach-policy [policy policy-name] | vlan {add | except | none | remove | all} vlan [vlan1, vlan2, vlan3...]]


DETAILED STEPS
 Command or ActionPurpose
Step 1
enable


Example:

Device> enable

 

Enables privileged EXEC mode.

  • Enter your password if prompted.
 
Step 2
configure terminal


Example:

Device# configure terminal

 

Enters global configuration mode.

 
Step 3
interface type number


Example:

Device(config)# interface fastethernet 0/0

 

Specifies an interface type and number, and places the device in interface configuration mode.

 
Step 4
ipv6 nd inspection [attach-policy [policy policy-name] | vlan {add | except | none | remove | all} vlan [vlan1, vlan2, vlan3...]]


Example:

Device(config-if)# ipv6 nd inspection

 

Applies the ND inspection feature on the interface.

 
Verifying and Troubleshooting IPv6 ND Inspection
These optional commands can be entered in any order to verify and troubleshoot the IPv6 ND inspection feature.
SUMMARY STEPS

1.    enable

2.    show ipv6 snooping capture-policy [interface type number]

3.    show ipv6 snooping counter [interface type number]

4.    show ipv6 snooping features

5.    show ipv6 snooping policies [interface type number]

6.    debug ipv6 snooping [binding-table | classifier | errors | feature-manager | filter acl | ha | hw-api | interface interface | memory | ndp-inspection | policy | vlan vlanid | switcher | filter acl | interface interface | vlanid]


DETAILED STEPS
 Command or ActionPurpose
Step 1
enable


Example:

Device> enable

 

Enables privileged EXEC mode.

  • Enter your password if prompted.
 
Step 2
show ipv6 snooping capture-policy [interface type number]


Example:

Device# show ipv6 snooping capture-policy interface ethernet 0/0

 

Displays snooping ND message capture policies.

 
Step 3
show ipv6 snooping counter [interface type number]


Example:

Device# show ipv6 snooping counter interface Fa 4/12

 

Displays information about the packets counted by the interface counter.

 
Step 4
show ipv6 snooping features


Example:

Device# show ipv6 snooping features

 

Displays information about snooping features configured on the device.

 
Step 5
show ipv6 snooping policies [interface type number]


Example:

Device# show ipv6 snooping policies

 

Displays information about the configured policies and the interfaces to which they are attached.

 
Step 6
debug ipv6 snooping [binding-table | classifier | errors | feature-manager | filter acl | ha | hw-api | interface interface | memory | ndp-inspection | policy | vlan vlanid | switcher | filter acl | interface interface | vlanid]


Example:

Device# debug ipv6 snooping

 

Enables debugging for snooping information in IPv6.

 

Configuring IPv6 Device Tracking

Configuring the IPv6 Binding Table Content
SUMMARY STEPS

1.    enable

2.    configure terminal

3.    ipv6 neighbor binding vlan vlan-id {interface type number | ipv6-address | mac-address} [tracking [disable | enable | retry-interval value] | reachable-lifetime value]

4.    ipv6 neighbor binding max-entries entries [vlan-limit number | interface-limit number | mac-limit number]

5.    ipv6 neighbor binding logging

6.    exit

7.    show ipv6 neighbor binding [vlan vlan-id | interface type number | ipv6 ipv6-address | mac mac-address]


DETAILED STEPS
 Command or ActionPurpose
Step 1
enable


Example:

Device> enable

 

Enables privileged EXEC mode.

  • Enter your password if prompted.
 
Step 2
configure terminal


Example:

Device# configure terminal

 

Enters global configuration mode.

 
Step 3
ipv6 neighbor binding vlan vlan-id {interface type number | ipv6-address | mac-address} [tracking [disable | enable | retry-interval value] | reachable-lifetime value]


Example:

Device(config)# ipv6 neighbor binding vlan 100 interface Ethernet 0/0 reachable-lifetime 100

 

Adds a static entry to the binding table database.

 
Step 4
ipv6 neighbor binding max-entries entries [vlan-limit number | interface-limit number | mac-limit number]


Example:

Device(config)# ipv6 neighbor binding max-entries 100

 

Specifies the maximum number of entries that are allowed to be inserted in the binding table cache.

 
Step 5
ipv6 neighbor binding logging


Example:

Device(config)# ipv6 neighbor binding logging

 

Enables the logging of binding table main events.

 
Step 6
exit


Example:

Device(config)# exit

 

Exits global configuration mode, and places the device in privileged EXEC mode.

 
Step 7
show ipv6 neighbor binding [vlan vlan-id | interface type number | ipv6 ipv6-address | mac mac-address]


Example:

Device# show ipv6 neighbor binding

 

Displays the contents of a binding table.

 
Configuring IPv6 Device Tracking

Perform this task to provide fine tuning for the life cycle of an entry in the binding table for the IPv6 device tracking feature For IPv6 device tracking to work, the binding table needs to be populated.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    ipv6 neighbor tracking [retry-interval value]


DETAILED STEPS
 Command or ActionPurpose
Step 1
enable


Example:

Device> enable

 

Enables privileged EXEC mode.

  • Enter your password if prompted.
 
Step 2
configure terminal


Example:

Device# configure terminal

 

Enters global configuration mode.

 
Step 3
ipv6 neighbor tracking [retry-interval value]


Example:

Device(config)# ipv6 neighbor tracking

 

Tracks entries in the binding table.

 

Configuring IPv6 Address Glean

Before You Begin

Note


You must configure an IPv6 snooping policy and attach the policy to a target before configuring IPv6 address glean.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    ipv6 snooping policy snooping-policy

4.   ipv6 snooping attach-policy snooping-policy

5.   prefix-glean [only ]


DETAILED STEPS
Step 1   enable


Example:
Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.
Step 2   configure terminal


Example:
Device# configure terminal

Enters global configuration mode.

Step 3   ipv6 snooping policy snooping-policy


Example:
Device(config)# ipv6 snooping policy policy1
Configures an IPv6 snooping policy named policy1 and enters IPv6 snooping configuration mode.
Step 4   ipv6 snooping attach-policy snooping-policy


Example:
Device(config-ipv6-snooping)# ipv6 snooping attach-policy policy1
Attaches the IPv6 snooping policy named policy1 to a target.
Step 5   prefix-glean [only ]


Example:
Device(config-ipv6-snooping)# prefix-glean
Enables the device to glean prefixes from IPv6 RAs or DHCPv6.

Configuration Examples for IPv6 Snooping

Example: Configuring IPv6 Snooping

Device(config)# ipv6 snooping policy policy1
Device(config-ipv6-snooping)# ipv6 snooping attach-policy policy1
Device(config-ipv6-snooping)# exit
. 
.
.
Device# show ipv6 snooping policies policy1
Policy policy1 configuration: 
  trusted-port
  device-role node
Policy applied on the following interfaces: 
   Et0/0    			vlan all
   Et1/0       vlan all 
Policy applied on the following vlans: 
   vlan 1-100,200,300-400

Example: IPv6 ND Inspection and RA Guard Configuration

This example provides information about an interface on which both the neighbor discovery (ND) inspection and router advertisement (RA) guard features are configured:

Device# show ipv6 snooping capture-policy interface ethernet 0/0

Hardware policy registered on Ethernet 0/0 
Protocol     Protocol value   Message   Value     Action    Feature 
ICMP         58               RS        85        punt      RA Guard 
                                                  punt      ND Inspection 
ICMP         58               RA        86        drop      RA guard 
                                                  punt      ND Inspection 
ICMP         58               NS        87        punt      ND Inspection 
ICM          58               NA        88        punt      ND Inspection 
ICMP         58               REDIR     89        drop      RA Guard 
                                                  punt      ND Inspection 

Example: IPv6 Device Tracking

Device# show ipv6 neighbor tracking

    IPv6 address               Link-Layer addr Interface vlan prlvl age   state      Time left
ND  FE80::A8BB:CCFF:FE01:F500  AABB.CC01.F500  Et0/0     100  0002    0   REACHABLE  8850
L   FE80::21D:71FF:FE99:4900   001D.7199.4900  Vl100     100  0080 7203   DOWN       N/A
ND  2001:600::1                AABB.CC01.F500  Et0/0     100  0003    0   REACHABLE  3181
ND  2001:300::1                AABB.CC01.F500  Et0/0     100  0007    0   REACHABLE  9559
L   2001:400::1                001D.7199.4900  Vl100     100  0080 7188   DOWN       N/A

      

Example: Configuring IPv6 Address Glean

<<Please provide an example--Thanks!>>

        
      

Additional References

Related Documents

Related Topic Document Title

IPv6 addressing and connectivity

IPv6 Configuration Guide

Cisco IOS commands

Cisco IOS Master Commands List, All Releases

IPv6 commands

Cisco IOS IPv6 Command Reference

Cisco IOS IPv6 features

Cisco IOS IPv6 Feature Mapping

Standards and RFCs

Standard/RFC Title

RFCs for IPv6

IPv6 RFCs

MIBs

MIB

MIBs Link

No new or modified MIBs are supported by this feature, and support for existing MIBs has not been modified by this feature.

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

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

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 IPv6 Snooping

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 1Feature Information for IPv6 Snooping
Feature Name Releases Feature Information

IPv6 Address Glean

15.0(2)SE

IPv6 address glean inspects ND and DHCP messages on a link to glean addresses and then populates the binding table with these addresses.

The following commands was introduced: prefix-glean.

IPv6 Device Tracking

12.2(50)SY

15.0(1)SY

15.0(2)SE

IPv6 device tracking provides IPv6 host liveness tracking so that a neighbor table can be immediately updated when an IPv6 host disappears.

The following commands were introduced or modified: ipv6 neighbor binding logging, ipv6 neighbor binding max-entries, ipv6 neighbor binding vlan, ipv6 neighbor tracking, show ipv6 neighbor binding.

IPv6 Neighbor Discovery Inspection

12.2(50)SY

15.0(1)SY

15.0(2)SE

IPv6 neighbor discovery inspection learns and secures bindings for stateless autoconfiguration addresses in Layer 2 neighbor tables.

The following commands were introduced or modified: debug ipv6 snooping, device-role, drop-unsecure, ipv6 nd inspection, ipv6 nd inspection policy, sec-level minimum, show ipv6 snooping capture-policy, show ipv6 snooping counters, show ipv6 snooping features, show ipv6 snooping policies, tracking, trusted-port.

IPv6 Snooping

15.0(2)SE

The IPv6 snooping feature bundles several layer 2 IPv6 first-hop security features, including IPv6 neighbor discovery, IPv6 device tracking, and IPv6 address glean. IPv6 snooping operates at layer 2, or between layer 2 and layer 3, and provides IPv6 features with security and scalability.

The following commands were introduced or modified: ipv6 snooping attach-policy, ipv6 snooping policy .

Glossary

  • CA--certification authority.
  • CGA--cryptographically generated address.
  • CPA--certificate path answer.
  • CPR--certificate path response.
  • CPS--certification path solicitation. The solicitation message used in the addressing process.
  • CRL--certificate revocation list.
  • CS--certification server.
  • CSR--certificate signing request.
  • DAD--duplicate address detection. A mechanism that ensures two IPv6 nodes on the same link are not using the same address.
  • DER--distinguished encoding rules. An encoding scheme for data values.
  • nonce--An unpredictable random or pseudorandom number generated by a node and used once. In SeND, nonces are used to assure that a particular advertisement is linked to the solicitation that triggered it.
  • non-SeND node--An IPv6 node that does not implement SeND but uses only the Neighbor Discovery protocol without security.
  • NUD--neighbor unreachability detection. A mechanism used for tracking neighbor reachability.
  • PACL--port-based access list.
  • PKI--public key infrastructure.
  • RA--router advertisement.
  • RD--Router discovery allows the hosts to discover what devices exist on the link and what subnet prefixes are available. Router discovery is a part of the Neighbor Discovery protocol.
  • Router Authorization Certificate--A public key certificate.
  • SeND node--An IPv6 node that implements SeND.
  • trust anchor--An entity that the host trusts to authorize devices to act as devices. Hosts are configured with a set of trust anchors to protect device discovery.

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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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