Configuring IPv6 First Hop Security

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Prerequisites for First Hop Security in IPv6

  • You have configured the necessary IPv6 enabled SDM template.

  • QoS should be enabled on the switch before configuring CoPP policies using mls qos command.

Restrictions for First Hop Security in IPv6

  • The following restrictions apply when applying FHS policies to EtherChannel interfaces (Port Channels):

    • A physical port with an FHS policy attached cannot join an EtherChannel group.

    • An FHS policy cannot be attached to an physical port when it is a member of an EtherChannel group.

  • By default, a snooping policy has a security-level of guard. When such a snooping policy is configured on an access switch, external IPv6 Router Advertisement (RA) or Dynamic Host Configuration Protocol for IPv6 (DHCPv6) server packets are blocked, even though the uplink port facing the router or DHCP server/relay is configured as a trusted port. To allow IPv6 RA or DHCPv6 server messages, do the following:

    • Apply an IPv6 RA-guard policy (for RA) or IPv6 DHCP-guard policy (for DHCP server messages ) on the uplink port.

    • Configure a snooping policy with a lower security-level, for example glean or inspect. However; configuring a lower security level is not recommended with such a snooping policy, because benefits of First Hop security features are not effective.

  • The following restrictions apply for CoPP policies with IPv6 SISF-based device tracking policies due to limitation reported in CSCvk32439:

    • CoPP policies are required to limit IPv6 NDP traffic when IPv6 SISF policies are configured on the switch.

    • After NDP CoPP policies are configured, limited traffic hits CPU. To accommodate the total end points connected, the number of NDP CoPP policies should be slightly more than the number of users connected to each switch in a stack. If you configure NDP CoPP policies less than the number of end points connected to the switch, the IP allocation to the end point is delayed but is not ignored completely.


      Note

      For example, if a stack of 5 switches has approximately 300 users, the NDP CoPP policies should be more than 300.

    • The DHCPv6 (server-to-client and client-to-server) CoPP policies are required only if Lightweight DHCPv6 Relay Agent (LDRA) is configured under IPv6 SISF-based device tracking policies on the switch.

Information about First Hop Security in IPv6

First Hop Security in IPv6 (FHS IPv6) is a set of IPv6 security features, the policies of which can be attached to a physical interface, or a VLAN. An IPv6 software policy database service stores and accesses these policies. When a policy is configured or modified, the attributes of the policy are stored or updated in the software policy database, then applied as was specified. The following IPv6 policies are currently supported:

  • IPv6 Snooping Policy—IPv6 Snooping Policy acts as a container policy that enables most of the features available with FHS in IPv6.

  • IPv6 FHS Binding Table Content—A database table of IPv6 neighbors connected to the switch is created from information sources such as Neighbor Discovery (ND) protocol snooping. This database, or binding, table is used by various IPv6 guard features (such as IPv6 ND Inspection) 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 Neighbor Discovery 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 conform are dropped. An ND message is considered trustworthy if its IPv6-to-Media Access Control (MAC) mapping is verifiable.

    This feature mitigates some of the inherent vulnerabilities of the ND mechanism, such as attacks on DAD, address resolution, router discovery, and the neighbor cache.

  • IPv6 Router Advertisement Guard—The IPv6 Router Advertisement (RA) guard feature enables the network administrator to block or reject unwanted or rogue RA guard messages that arrive at the network switch platform. RAs are used by routers to announce themselves on the link. The RA Guard feature analyzes the RAs and filters out bogus RAs sent by unauthorized routers. In host mode, all router advertisement and router redirect messages are disallowed on the port. The RA guard feature compares configuration information on the Layer 2 device with the information found in the received RA frame. Once the Layer 2 device has validated the content of the RA frame and router redirect frame against the configuration, it forwards the RA to its unicast or multicast destination. If the RA frame content is not validated, the RA is dropped.

  • IPv6 DHCP Guard—The IPv6 DHCP Guard feature blocks reply and advertisement messages that come from unauthorized DHCPv6 servers and relay agents. IPv6 DHCP guard can prevent forged messages from being entered in the binding table and block DHCPv6 server messages when they are received on ports that are not explicitly configured as facing a DHCPv6 server or DHCP relay. To use this feature, configure a policy and attach it to an interface or a VLAN. To debug DHCP guard packets, use the debug ipv6 snooping dhcp-guard privileged EXEC command.

  • IPv6 Source Guard—Like IPv4 Source Guard, IPv6 Source Guard validates the source address or prefix to prevent source address spoofing.

    A source guard programs the hardware to allow or deny traffic based on source or destination addresses. It deals exclusively with data packet traffic.

    To debug source-guard packets, use the debug ipv6 snooping source-guard privileged EXEC command.

    The following restrictions apply:

    • An FHS policy cannot be attached to an physical port when it is a member of an EtherChannel group.

    • When IPv6 source guard is enabled on a switch port, NDP or DHCP snooping must be enabled on the interface to which the switch port belongs. Otherwise, all data traffic from this port will be blocked.

    • An IPv6 source guard policy cannot be attached to a VLAN. It is supported only at the interface level.

    • When you configure IPv4 and IPv6 source guard together on an interface, it is recommended to use ip verify source mac-check instead of ip verify source . IPv4 connectivity on a given port might break due to two different filtering rules set — one for IPv4 (IP-filter) and the other for IPv6 (IP-MAC filter).

    • You cannot use IPv6 Source Guard and Prefix Guard together. When you attach the policy to an interface, it should be "validate address" or "validate prefix" but not both.

    • PVLAN and Source/Prefix Guard cannot be applied together.

      For more information on IPv6 Source Guard, see the IPv6 Source Guard chapter of the Cisco IOS IPv6 Configuration Guide Library on Cisco.com.

    • IPv6 Prefix Guard—The IPv6 prefix guard feature works within the IPv6 source guard feature, to enable the device to deny traffic originated from non-topologically correct addresses. IPv6 prefix guard is often used when IPv6 prefixes are delegated to devices (for example, home gateways) using DHCP prefix delegation. The feature discovers ranges of addresses assigned to the link and blocks any traffic sourced with an address outside this range.

      For more information on IPv6 Prefix Guard, see the IPv6 Prefix Guard chapter of the Cisco IOS IPv6 Configuration Guide Library on Cisco.com.

    • IPv6 Destination Guard—The IPv6 destination guard feature works with IPv6 neighbor discovery to ensure that the device performs address resolution only for those addresses that are known to be active on the link. It relies on the address glean functionality to populate all destinations active on the link into the binding table and then blocks resolutions before they happen when the destination is not found in the binding table.

      For more information about IPv6 Destination Guard, see the IPv6 Destination Guard chapter of the Cisco IOS IPv6 Configuration Guide Library on Cisco.com.

    • IPv6 Neighbor Discovery Multicast Suppress—The IPv6 Neighbor Discovery multicast suppress feature is an IPv6 snooping feature that runs on a switch or a wireless controller and is used to reduce the amount of control traffic necessary for proper link operations.

    • DHCPv6 Relay—Lightweight DHCPv6 Relay Agent—The DHCPv6 Relay—Lightweight DHCPv6 Relay Agent feature allows relay agent information to be inserted by an access node that performs a link-layer bridging (non-routing) function. Lightweight DHCPv6 Relay Agent (LDRA) functionality can be implemented in existing access nodes, such as DSL access multiplexers (DSLAMs) and Ethernet switches, that do not support IPv6 control or routing functions. LDRA is used to insert relay-agent options in DHCP version 6 (DHCPv6) message exchanges primarily to identify client-facing interfaces. LDRA functionality can be enabled on an interface and on a VLAN.


      Note

      If an LDRA device is directly connected to a client, the interface must have the pool configuration to fetch the specific subnet or link information at the server side. In this case, if the LDRA device is present in different subnets or links, the server may not be able to fetch the correct subnet. You can now configure the pool name in the interface so as to choose the proper subnet or link for the client.

      For more information about DHCPv6 Relay, See the DHCPv6 Relay—Lightweight DHCPv6 Relay Agent section of the IP Addressing: DHCP Configuration Guide, Cisco IOS Release 15.1SG.

    How to Configure an IPv6 Snooping Policy

    Beginning in privileged EXEC mode, follow these steps to configure IPv6 Snooping Policy :

    Procedure

      Command or Action Purpose
    Step 1

    configure terminal

    Example:

    Switch# configure terminal

    Enters the global configuration mode.

    Step 2

    ipv6 snooping policy policy-name

    Example:

    Switch(config)# ipv6 snooping policy example_policy

    Creates a snooping policy and enters IPv6 Snooping Policy Configuration mode.

    Step 3

    {[default ] | [device-role {node | switch}] | [limit address-count value] | [no] | [protocol {dhcp | ndp} ] | [security-level {glean | guard | inspect} ] | [tracking {disable [stale-lifetime [seconds | infinite] | enable [reachable-lifetime [seconds | infinite] } ] | [trusted-port ] }

    Example:

    Switch(config-ipv6-snooping)# security-level inspect

    Example:

    Switch(config-ipv6-snooping)# trusted-port

    Enables data address gleaning, validates messages against various criteria, specifies the security level for messages.

    • (Optional) default—Sets all to default options.

    • (Optional) device-role{node] | switch}—Specifies the role of the device attached to the port. Default is node.

    • (Optional) limit address-count value—Limits the number of addresses allowed per target.

    • (Optional) no—Negates a command or sets it to defaults.

    • (Optional) protocol{dhcp | ndp}—Specifies which protocol should be redirected to the snooping feature for analysis. The default, is dhcp and ndp. To change the default, use the no protocol command.

    • (Optional) security-level{glean|guard|inspect}—Specifies the level of security enforced by the feature. Default is guard.

      • glean—Gleans addresses from messages and populates the binding table without any verification.
      • guard—Gleans addresses and inspects messages. In addition, it rejects RA and DHCP server messages. This is the default option.
      • inspect—Gleans addresses, validates messages for consistency and conformance, and enforces address ownership.

    • (Optional) tracking {disable | enable}—Overrides the default tracking behavior and specifies a tracking option.

    • (Optional) trusted-port—Sets up a trusted port. It disables the guard on applicable targets. Bindings learned through a trusted port have preference over bindings learned through any other port. A trusted port is given preference in case of a collision while making an entry in the table.

    Step 4

    end

    Example:

    Switch(config-ipv6-snooping)# exit

    Exits configuration modes to Privileged EXEC mode.

    Step 5

    show ipv6 snooping policy policy-name

    Example:

    Switch#show ipv6 snooping policy example_policy

    Displays the snooping policy configuration.

    What to do next

    Attach an IPv6 Snooping policy to interfaces or VLANs.

    How to Attach an IPv6 Snooping Policy to an Interface

    Beginning in privileged EXEC mode, follow these steps to attach an IPv6 Snooping policy on an interface or VLAN:

    Procedure

      Command or Action Purpose
    Step 1

    configure terminal

    Example:

    Switch# configure terminal

    Enters the global configuration mode.
    Step 2

    interface Interface_type stack/module/port

    Example:

    Switch(config)#  interface gigabitethernet 1/1/4

    Specifies an interface type and identifier; enters the interface configuration mode.
    Step 3

    switchport

    Example:

    Switch(config-if)# switchport

    Enters the Switchport mode.

    Note 

    To configure Layer 2 parameters, if the interface is in Layer 3 mode, you must enter the switchport interface configuration command without any parameters to put the interface into Layer 2 mode. This shuts down the interface and then re-enables it, which might generate messages on the device to which the interface is connected. When you put an interface that is in Layer 3 mode into Layer 2 mode, the previous configuration information related to the affected interface might be lost, and the interface is returned to its default configuration. The command prompt displays as (config-if)# in Switchport configuration mode.

    Step 4

    ipv6 snooping [attach-policy policy_name [ vlan {vlan_id | add vlan_ids | exceptvlan_ids | none | remove vlan_ids}] | vlan {vlan_id | add vlan_ids | exceptvlan_ids | none | remove vlan_ids | all} ]

    Example:

    Switch(config-if)# ipv6 snooping 

or 

Switch(config-if)# ipv6 snooping attach-policy example_policy

or
Switch(config-if)# ipv6 snooping vlan 111,112

or 

Switch(config-if)# ipv6 snooping attach-policy example_policy vlan 111,112

    Attaches a custom ipv6 snooping policy to the interface or the specified VLANs on the interface. To attach the default policy to the interface, use the ipv6 snooping command without the attach-policy keyword. To attach the default policy to VLANs on the interface, use the ipv6 snooping vlan command. The default policy is, security-level guard, device-role node, protocol ndp and dhcp.

    Step 5

    do show running-config

    Example:

    Switch#(config-if)#  do show running-config

    Verifies that the policy is attached to the specified interface without exiting the interface configuration mode.

    How to Attach an IPv6 Snooping Policy to a Layer 2 EtherChannel Interface

    Beginning in privileged EXEC mode, follow these steps to attach an IPv6 Snooping policy on an EtherChannel interface or VLAN:

    Procedure

      Command or Action Purpose
    Step 1

    configure terminal

    Example:

    Switch# configure terminal

    Enters the global configuration mode.

    Step 2

    interface range Interface_name

    Example:

    Switch(config)#  interface range Po11

    Specify the port-channel interface name assigned when the EtherChannel was created. Enters the interface range configuration mode.

    Tip 

    Enter the do show interfaces summary command for quick reference to interface names and types.

    Step 3

    ipv6 snooping [attach-policy policy_name [ vlan {vlan_ids | add vlan_ids | except vlan_ids | none | remove vlan_ids | all} ] | vlan [ {vlan_ids | add vlan_ids | exceptvlan_ids | none | remove vlan_ids | all} ]

    Example:

    Switch(config-if-range)# ipv6 snooping attach-policy example_policy

or

Switch(config-if-range)# ipv6 snooping attach-policy example_policy vlan 222,223,224

or 

Switch(config-if-range)#ipv6 snooping vlan 222, 223,224

    Attaches the IPv6 Snooping policy to the interface or the specified VLANs on that interface. The default policy is attached if the attach-policy option is not used.

    Step 4

    do show running-config interfaceportchannel_interface_name

    Example:

    Switch#(config-if-range)#  do show running-config int po11

    Confirms that the policy is attached to the specified interface without exiting the configuration mode.

    How to Attach an IPv6 Snooping Policy to VLANs Globally

    Beginning in privileged EXEC mode, follow these steps to attach an IPv6 Snooping Policy to VLANs across multiple interfaces:

    Procedure

      Command or Action Purpose
    Step 1

    configure terminal

    Example:

    Switch# configure terminal

    Enters the global configuration mode.
    Step 2

    vlan configuration vlan_list

    Example:

    Switch(config)#  vlan configuration 333

    Specifies the VLANs to which the IPv6 Snooping policy will be attached ; enters the VLAN interface configuration mode.
    Step 3

    ipv6 snooping [attach-policy policy_name]

    Example:

    Switch(config-vlan-config)#ipv6 snooping attach-policy example_policy

    Attaches the IPv6 Snooping policy to the specified VLANs across all switch and stack interfaces. The default policy is attached if the attach-policy option is not used. The default policy is, security-level guard, device-role node, protocol ndp and dhcp.

    Step 4

    do show running-config

    Example:

    Switch#(config-if)#  do show running-config

    Verifies that the policy is attached to the specified VLANs without exiting the interface configuration mode.

    How to Configure the IPv6 Binding Table Content

    Beginning in privileged EXEC mode, follow these steps to configure IPv6 Binding Table Content :

    Procedure

      Command or Action Purpose
    Step 1

    configure terminal

    Example:

    Switch# configure terminal

    Enters the global configuration mode.

    Step 2

    [no] ipv6 neighbor binding [vlan vlan-id {ipv6-address interface interface_type stack/module/port hw_address [reachable-lifetimevalue [seconds | default | infinite] | [tracking{ [default | disable] [ reachable-lifetimevalue [seconds | default | infinite] | [enable [reachable-lifetimevalue [seconds | default | infinite] | [retry-interval {seconds| default [reachable-lifetimevalue [seconds | default | infinite] } ]

    Example:

    Switch(config)#  ipv6 neighbor binding

    Adds a static entry to the binding table database.

    Step 3

    [no] ipv6 neighbor binding max-entries number [mac-limit number | port-limit number [mac-limit number] | vlan-limit number [ [mac-limit number] | [port-limit number [mac-limitnumber] ] ] ]

    Example:

    Switch(config)#  ipv6 neighbor binding max-entries 30000

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

    Step 4

    ipv6 neighbor binding logging

    Example:

    Switch(config)# ipv6 neighbor binding logging

    Enables the logging of binding table main events.

    Step 5

    exit

    Example:

    Switch(config)# exit

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

    Step 6

    show ipv6 neighbor binding

    Example:

    Switch#  show ipv6 neighbor binding

    Displays contents of a binding table.

    How to Configure an IPv6 Neighbor Discovery Inspection Policy

    Beginning in privileged EXEC mode, follow these steps to configure an IPv6 ND Inspection Policy:

    Procedure

      Command or Action Purpose
    Step 1

    configure terminal

    Example:

    Switch# configure terminal

    Enters the global configuration mode.

    Step 2

    [no]ipv6 nd inspection policy policy-name

    Example:

    Switch(config)# ipv6 nd inspection policy example_policy

    Specifies the ND inspection policy name and enters ND Inspection Policy configuration mode.

    Step 3

    device-role {host | monitor | router | switch}

    Example:

    Switch(config-nd-inspection)# device-role switch

    Specifies the role of the device attached to the port. The default is host.

    Step 4

    drop-unsecure

    Example:

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

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

    Step 5

    limit address-count value

    Example:

    Switch(config-nd-inspection)# limit address-count 1000

    Enter 1–10,000.

    Step 6

    sec-level minimum value

    Example:

    Switch(config-nd-inspection)# limit address-count 1000

    Specifies the minimum security level parameter value when Cryptographically Generated Address (CGA) options are used.

    Step 7

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

    Example:

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

    Overrides the default tracking policy on a port.

    Step 8

    trusted-port

    Example:

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

    Configures a port to become a trusted port.

    Step 9

    validate source-mac

    Example:

    Switch(config-nd-inspection)# validate source-mac

    Checks the source media access control (MAC) address against the link-layer address.

    Step 10

    no {device-role | drop-unsecure | limit address-count | sec-level minimum | tracking | trusted-port | validate source-mac}

    Example:

    Switch(config-nd-inspection)# no validate source-mac

    Remove the current configuration of a parameter with the no form of the command.

    Step 11

    default {device-role | drop-unsecure | limit address-count | sec-level minimum | tracking | trusted-port | validate source-mac}

    Example:

    Switch(config-nd-inspection)# default limit address-count

    Restores configuration to the default values.

    Step 12

    do show ipv6 nd inspection policy policy_name

    Example:

    Switch(config-nd-inspection)# do show ipv6 nd inspection policy example_policy

    Verifies the ND Inspection Configuration without exiting ND inspection configuration mode.

    How to Attach an IPv6 Neighbor Discovery Inspection Policy to an Interface

    Beginning in privileged EXEC mode, follow these steps to attach an IPv6 ND Inspection policy to an interface or VLANs on an interface :

    Procedure

      Command or Action Purpose
    Step 1

    configure terminal

    Example:

    Switch# configure terminal

    Enters the global configuration mode.
    Step 2

    interface Interface_type stack/module/port

    Example:

    Switch(config)#  interface gigabitethernet 1/1/4

    Specifies an interface type and identifier; enters the interface configuration mode.
    Step 3

    ipv6 nd inspection [attach-policy policy_name [ vlan {vlan_ids | add vlan_ids | except vlan_ids | none | remove vlan_ids | all} ] | vlan [ {vlan_ids | add vlan_ids | exceptvlan_ids | none | remove vlan_ids | all} ]

    Example:

    Switch(config-if)# ipv6 nd inspection attach-policy example_policy

or

Switch(config-if)# ipv6 nd inspection attach-policy example_policy vlan 222,223,224

or 

Switch(config-if)# ipv6 nd inspection vlan 222, 223,224

    Attaches the Neighbor Discovery Inspection policy to the interface or the specified VLANs on that interface. The default policy is attached if the attach-policy option is not used.

    Step 4

    do show running-config

    Example:

    Switch#(config-if)#  do show running-config

    Verifies that the policy is attached to the specified interface without exiting the interface configuration mode.

    How to Attach an IPv6 Neighbor Discovery Inspection Policy to a Layer 2 EtherChannel Interface

    Beginning in privileged EXEC mode, follow these steps to attach an IPv6 Neighbor Discovery Inspection policy on an EtherChannel interface or VLAN:

    Procedure

      Command or Action Purpose
    Step 1

    configure terminal

    Example:

    Switch# configure terminal

    Enters the global configuration mode.

    Step 2

    interface range Interface_name

    Example:

    Switch(config)#  interface Po11

    Specify the port-channel interface name assigned when the EtherChannel was created. Enters the interface range configuration mode.

    Tip 

    Enter the do show interfaces summary command for quick reference to interface names and types.

    Step 3

    ipv6 nd inspection [attach-policy policy_name [ vlan {vlan_ids | add vlan_ids | except vlan_ids | none | remove vlan_ids | all} ] | vlan [ {vlan_ids | add vlan_ids | exceptvlan_ids | none | remove vlan_ids | all} ]

    Example:

    Switch(config-if-range)# ipv6 nd inspection attach-policy example_policy

or

Switch(config-if-range)# ipv6 nd inspection attach-policy example_policy vlan 222,223,224

or 

Switch(config-if-range)#ipv6 nd inspection vlan 222, 223,224

    Attaches the ND Inspection policy to the interface or the specified VLANs on that interface. The default policy is attached if the attach-policy option is not used.

    Step 4

    do show running-config interfaceportchannel_interface_name

    Example:

    Switch#(config-if-range)#  do show running-config int po11

    Confirms that the policy is attached to the specified interface without exiting the configuration mode.

    How to Attach an IPv6 Neighbor Discovery Inspection Policy to VLANs Globally

    Beginning in privileged EXEC mode, follow these steps to attach an IPv6 ND Inspection policy to VLANs across multiple interfaces:

    Procedure

      Command or Action Purpose
    Step 1

    configure terminal

    Example:

    Switch# configure terminal

    Enters the global configuration mode.
    Step 2

    vlan configuration vlan_list

    Example:

    Switch(config)# vlan configuration 334

    Specifies the VLANs to which the IPv6 Snooping policy will be attached ; enters the VLAN interface configuration mode.
    Step 3

    ipv6 nd inspection [attach-policy policy_name]

    Example:

    Switch(config-vlan-config)#ipv6 nd inspection attach-policy example_policy

    Attaches the IPv6 Neighbor Discovery policy to the specified VLANs across all switch and stack interfaces. The default policy is attached if the attach-policy option is not used.

    The default policy is, device-role host, no drop-unsecure, limit address-count disabled, sec-level minimum is disabled, tracking is disabled, no trusted-port, no validate source-mac.

    Step 4

    do show running-config

    Example:

    Switch#(config-if)#  do show running-config

    Confirms that the policy is attached to the specified VLANs without exiting the configuration mode.

    How to Configure an IPv6 Router Advertisement Guard Policy

    Beginning in privileged EXEC mode, follow these steps to configure an IPv6 Router Advertisement policy :

    Procedure

      Command or Action Purpose
    Step 1

    configure terminal

    Example:

    Switch# configure terminal

    Enters the global configuration mode.

    Step 2

    [no]ipv6 nd raguard policy policy-name

    Example:

    Switch(config)# ipv6 nd raguard policy example_policy

    Specifies the RA Guard policy name and enters RA Guard Policy configuration mode.

    Step 3

    [no]device-role {host | monitor | router | switch}

    Example:

    Switch(config-nd-raguard)# device-role switch

    Specifies the role of the device attached to the port. The default is host.

    Step 4

    [no]hop-limit {maximum | minimum} value

    Example:

    Switch(config-nd-raguard)# hop-limit maximum 33

    (1–255) Range for Maximum and Minimum Hop Limit values.

    Enables filtering of Router Advertisement messages by the Hop Limit value. A rogue RA message may have a low Hop Limit value (equivalent to the IPv4 Time to Live) that when accepted by the host, prevents the host from generating traffic to destinations beyond the rogue RA message generator. An RA message with an unspecified Hop Limit value is blocked.

    If not configured, this filter is disabled. Configure minimum to block RA messages with Hop Limit values lower than the value you specify. Configure maximumto block RA messages with Hop Limit values greater than the value you specify.

    Step 5

    [no]managed-config-flag {off | on}

    Example:

    Switch(config-nd-raguard)# managed-config-flag on

    Enables filtering of Router Advertisement messages by the Managed Address Configuration, or "M" flag field. A rouge RA message with an M field of 1 can cause a host to use a rogue DHCPv6 server. If not configured, this filter is disabled.

    On—Accepts and forwards RA messages with an M value of 1, blocks those with 0.

    Off—Accepts and forwards RA messages with an M value of 0, blocks those with 1.

    Step 6

    [no]match {ipv6 access-list list | ra prefix-list list}

    Example:

    Switch(config-nd-raguard)# match ipv6 access-list example_list

    Matches a specified prefix list or access list.

    Step 7

    [no]other-config-flag {on | off}

    Example:

    Switch(config-nd-raguard)# other-config-flag on

    Enables filtering of Router Advertisement messages by the Other Configuration, or "O" flag field. A rouge RA message with an O field of 1 can cause a host to use a rogue DHCPv6 server. If not configured, this filter is disabled.

    On—Accepts and forwards RA messages with an O value of 1, blocks those with 0.

    Off—Accepts and forwards RA messages with an O value of 0, blocks those with 1.

    Step 8

    [no]router-preference maximum {high | medium | low}

    Example:

    Switch(config-nd-raguard)# router-preference maximum high

    Enables filtering of Router Advertisement messages by the Router Preference flag. If not configured, this filter is disabled.

    • high—Accepts RA messages with the Router Preference set to high, medium, or low.

    • medium—Blocks RA messages with the Router Preference set to high.

    • low—Blocks RA messages with the Router Preference set to medium and high.

    Step 9

    [no]trusted-port

    Example:

    Switch(config-nd-raguard)# trusted-port

    When configured as a trusted port, all attached devices are trusted, and no further message verification is performed.

    Step 10

    default {device-role | hop-limit {maximum | minimum} | managed-config-flag | match {ipv6 access-list | ra prefix-list } | other-config-flag | router-preference maximum| trusted-port}

    Example:

    Switch(config-nd-raguard)# default hop-limit

    Restores a command to its default value.

    Step 11

    do show ipv6 nd raguard policy policy_name

    Example:

    Switch(config-nd-raguard)# do show ipv6 nd raguard policy example_policy

    (Optional)—Displays the ND Guard Policy configuration without exiting the RA Guard policy configuration mode.

    How to Attach an IPv6 Router Advertisement Guard Policy to an Interface

    Beginning in privileged EXEC mode, follow these steps to attach an IPv6 Router Advertisement policy to an interface or to VLANs on the interface :

    Procedure

      Command or Action Purpose
    Step 1

    configure terminal

    Example:

    Switch# configure terminal

    Enters the global configuration mode.
    Step 2

    interface Interface_type stack/module/port

    Example:

    Switch(config)#  interface gigabitethernet 1/1/4

    Specifies an interface type and identifier; enters the interface configuration mode.
    Step 3

    ipv6 nd raguard [attach-policy policy_name [ vlan {vlan_ids | add vlan_ids | except vlan_ids | none | remove vlan_ids | all} ] | vlan [ {vlan_ids | add vlan_ids | exceptvlan_ids | none | remove vlan_ids | all} ]

    Example:

    Switch(config-if)# ipv6 nd raguard attach-policy example_policy

or

Switch(config-if)# ipv6 nd raguard attach-policy example_policy vlan 222,223,224

or 

Switch(config-if)# ipv6 nd raguard vlan 222, 223,224

    Attaches the Neighbor Discovery Inspection policy to the interface or the specified VLANs on that interface. The default policy is attached if the attach-policy option is not used.

    Step 4

    do show running-config

    Example:

    Switch#(config-if)#  do show running-config

    Confirms that the policy is attached to the specified interface without exiting the configuration mode.

    How to Attach an IPv6 Router Advertisement Guard Policy to a Layer 2 EtherChannel Interface

    Beginning in privileged EXEC mode, follow these steps to attach an IPv6 Router Advertisement Guard Policy on an EtherChannel interface or VLAN:

    Procedure

      Command or Action Purpose
    Step 1

    configure terminal

    Example:

    Switch# configure terminal

    Enters the global configuration mode.

    Step 2

    interface range Interface_name

    Example:

    Switch(config)#  interface Po11

    Specify the port-channel interface name assigned when the EtherChannel was created. Enters the interface range configuration mode.

    Tip 

    Enter the do show interfaces summary command for quick reference to interface names and types.

    Step 3

    ipv6 nd raguard [attach-policy policy_name [ vlan {vlan_ids | add vlan_ids | except vlan_ids | none | remove vlan_ids | all} ] | vlan [ {vlan_ids | add vlan_ids | exceptvlan_ids | none | remove vlan_ids | all} ]

    Example:

    Switch(config-if-range)# ipv6 nd raguard attach-policy example_policy

or

Switch(config-if-range)# ipv6 nd raguard attach-policy example_policy vlan 222,223,224

or 

Switch(config-if-range)#ipv6 nd raguard vlan 222, 223,224

    Attaches the RA Guard policy to the interface or the specified VLANs on that interface. The default policy is attached if the attach-policy option is not used.

    Step 4

    do show running-config interfaceportchannel_interface_name

    Example:

    Switch#(config-if-range)#  do show running-config int po11

    Confirms that the policy is attached to the specified interface without exiting the configuration mode.

    How to Attach an IPv6 Router Advertisement Guard Policy to VLANs Globally

    Beginning in privileged EXEC mode, follow these steps to attach an IPv6 Router Advertisement policy to VLANs regardless of interface:

    Procedure

      Command or Action Purpose
    Step 1

    configure terminal

    Example:

    Switch# configure terminal

    Enters global configuration mode.

    Step 2

    vlan configuration vlan_list

    Example:

    Switch(config)# vlan configuration 335

    Specifies the VLANs to which the IPv6 RA Guard policy will be attached ; enters the VLAN interface configuration mode.

    Step 3

    ipv6 dhcp guard [attach-policy policy_name]

    Example:

    Switch(config-vlan-config)#ipv6 nd raguard attach-policy example_policy

    Attaches the IPv6 RA Guard policy to the specified VLANs across all switch and stack interfaces. The default policy is attached if the attach-policy option is not used.

    Step 4

    do show running-config

    Example:

    Switch#(config-if)#  do show running-config

    Confirms that the policy is attached to the specified VLANs without exiting the configuration mode.

    How to Configure an IPv6 DHCP Guard Policy

    Beginning in privileged EXEC mode, follow these steps to configure an IPv6 DHCP (DHCPv6) Guard policy:

    Procedure

      Command or Action Purpose
    Step 1

    configure terminal

    Example:

    Switch# configure terminal

    Enters the global configuration mode.

    Step 2

    [no]ipv6 dhcp guard policy policy-name

    Example:

    Switch(config)# ipv6 dhcp guard policy example_policy

    Specifies the DHCPv6 Guard policy name and enters DHCPv6 Guard Policy configuration mode.

    Step 3

    [no]device-role {client | server}

    Example:

    Switch(config-dhcp-guard)# device-role server

    (Optional) Filters out DHCPv6 replies and DHCPv6 advertisements on the port that are not from a device of the specified role. Default is client.

    • client—Default value, specifies that the attached device is a client. Server messages are dropped on this port.

    • server—Specifies that the attached device is a DHCPv6 server. Server messages are allowed on this port.

    Step 4

    [no] match server access-list ipv6-access-list-name

    Example:

    
;;Assume a preconfigured IPv6 Access List as follows:
Switch(config)# ipv6 access-list my_acls
Switch(config-ipv6-acl)# permit host FE80::A8BB:CCFF:FE01:F700 any
 
;;configure DCHPv6 Guard to match approved access list.
Switch(config-dhcp-guard)#  match server access-list my_acls

    (Optional). Enables verification that the advertised DHCPv6 server or relay address is from an authorized server access list (The destination address in the access list is 'any'). If not configured, this check will be bypassed. An empty access list is treated as a permit all.

    Step 5

    [no] match reply prefix-list ipv6-prefix-list-name

    Example:

    
;;Assume a preconfigured IPv6 prefix list as follows:
Switch(config)# ipv6 prefix-list my_prefix permit 2001:0DB8::/64 le 128

;; Configure DCHPv6 Guard to match prefix
Switch(config-dhcp-guard)#  match reply prefix-list my_prefix

    (Optional) Enables verification of the advertised prefixes in DHCPv6 reply messages from the configured authorized prefix list. If not configured, this check will be bypassed. An empty prefix list is treated as a permit.

    Step 6

    [no]preference{ max limit | min limit }

    Example:

    Switch(config-dhcp-guard)# preference max 250
Switch(config-dhcp-guard)#preference min 150

    Configure max and min when device-role is serverto filter DCHPv6 server advertisements by the server preference value. The defaults permit all advertisements.

    max limit—(0 to 255) (Optional) Enables verification that the advertised preference (in preference option) is less than the specified limit. Default is 255. If not specified, this check will be bypassed.

    min limit—(0 to 255) (Optional) Enables verification that the advertised preference (in preference option) is greater than the specified limit. Default is 0. If not specified, this check will be bypassed.

    Step 7

    [no] trusted-port

    Example:

    Switch(config-dhcp-guard)# trusted-port

    (Optional) trusted-port—Sets the port to a trusted mode. No further policing takes place on the port.

    Note 

    If you configure a trusted port then the device-role option is not available.

    Step 8

    default {device-role | trusted-port}

    Example:

    Switch(config-dhcp-guard)# default device-role

    (Optional) default—Sets a command to its defaults.

    Step 9

    do show ipv6 dhcp guard policy policy_name

    Example:

    Switch(config-dhcp-guard)# do show ipv6 dhcp guard policy example_policy

    (Optional) Displays the configuration of the IPv6 DHCP guard policy without leaving the configuration submode. Omitting the policy_name variable displays all DHCPv6 policies.

    Example of DHCPv6 Guard Configuration 

    enable
configure terminal
ipv6 access-list acl1
 permit host FE80::A8BB:CCFF:FE01:F700 any
ipv6 prefix-list abc permit 2001:0DB8::/64 le 128	
ipv6 dhcp guard policy pol1
 device-role server
 match server access-list acl1
 match reply prefix-list abc
 preference min 0
 preference max 255
 trusted-port
interface GigabitEthernet 0/2/0
 switchport
 ipv6 dhcp guard attach-policy pol1 vlan add 1
 vlan 1
  ipv6 dhcp guard attach-policy pol1
show ipv6 dhcp guard policy pol1

    How to Attach an IPv6 DHCP Guard Policy to an Interface or a VLAN on an Interface

    Beginning in privileged EXEC mode, follow these steps to configure IPv6 Binding Table Content :

    Procedure

      Command or Action Purpose
    Step 1

    configure terminal

    Example:

    Switch# configure terminal

    Enters the global configuration mode.
    Step 2

    interface Interface_type stack/module/port

    Example:

    Switch(config)#  interface gigabitethernet 1/1/4

    Specifies an interface type and identifier; enters the interface configuration mode.
    Step 3

    ipv6 dhcp guard [attach-policy policy_name [ vlan {vlan_ids | add vlan_ids | except vlan_ids | none | remove vlan_ids | all} ] | vlan [ {vlan_ids | add vlan_ids | exceptvlan_ids | none | remove vlan_ids | all} ]

    Example:

    Switch(config-if)# ipv6 dhcp guard attach-policy example_policy

or

Switch(config-if)# ipv6 dhcp guard attach-policy example_policy vlan 222,223,224

or 

Switch(config-if)# ipv6 dhcp guard vlan 222, 223,224

    Attaches the DHCP Guard policy to the interface or the specified VLANs on that interface. The default policy is attached if the attach-policy option is not used.

    Step 4

    do show running-config interface Interface_type stack/module/port

    Example:

    Switch#(config-if)#  do show running-config gig 1/1/4

    Confirms that the policy is attached to the specified interface without exiting the configuration mode.

    How to Attach an IPv6 DHCP Guard Policy to a Layer 2 EtherChannel Interface

    Beginning in privileged EXEC mode, follow these steps to attach an IPv6 DHCP Guard policy on an EtherChannel interface or VLAN:

    Procedure

      Command or Action Purpose
    Step 1

    configure terminal

    Example:

    Switch# configure terminal

    Enters the global configuration mode.

    Step 2

    interface range Interface_name

    Example:

    Switch(config)#  interface Po11

    Specify the port-channel interface name assigned when the EtherChannel was created. Enters the interface range configuration mode.

    Tip 

    Enter the do show interfaces summary command for quick reference to interface names and types.

    Step 3

    ipv6 dhcp guard [attach-policy policy_name [ vlan {vlan_ids | add vlan_ids | except vlan_ids | none | remove vlan_ids | all} ] | vlan [ {vlan_ids | add vlan_ids | exceptvlan_ids | none | remove vlan_ids | all} ]

    Example:

    Switch(config-if-range)# ipv6 dhcp guard attach-policy example_policy

or

Switch(config-if-range)# ipv6 dhcp guard attach-policy example_policy vlan 222,223,224

or 

Switch(config-if-range)#ipv6 dhcp guard vlan 222, 223,224

    Attaches the DHCP Guard policy to the interface or the specified VLANs on that interface. The default policy is attached if the attach-policy option is not used.

    Step 4

    do show running-config interfaceportchannel_interface_name

    Example:

    Switch#(config-if-range)#  do show running-config int po11

    Confirms that the policy is attached to the specified interface without exiting the configuration mode.

    How to Attach an IPv6 DHCP Guard Policy to VLANs Globally

    Beginning in privileged EXEC mode, follow these steps to attach an IPv6 DHCP Guard policy to VLANs across multiple interfaces:

    Procedure

      Command or Action Purpose
    Step 1

    configure terminal

    Example:

    Switch# configure terminal

    Enters the global configuration mode.
    Step 2

    vlan configuration vlan_list

    Example:

    Switch(config)# vlan configuration 334

    Specifies the VLANs to which the IPv6 Snooping policy will be attached ; enters the VLAN interface configuration mode.
    Step 3

    ipv6 dhcp guard [attach-policy policy_name]

    Example:

    Switch(config-vlan-config)#ipv6 dhcp guard attach-policy example_policy

    Attaches the IPv6 Neighbor Discovery policy to the specified VLANs across all switch and stack interfaces. The default policy is attached if the attach-policy option is not used. The default policy is, device-role client, no trusted-port.

    Step 4

    do show running-config

    Example:

    Switch#(config-if)#  do show running-config

    Confirms that the policy is attached to the specified VLANs without exiting the configuration mode.

    How to Configure IPv6 Source Guard

    Procedure

      Command or Action Purpose
    Step 1

    enable

    Example:

    
Switch> enable

    Enables privileged EXEC mode.

    • Enter your password if prompted.

    Step 2

    configure terminal

    Example:

    Switch# configure terminal

    Enters the global configuration mode.

    Step 3

    [no] ipv6 source-guard policy policy_name

    Example:

    Switch(config)#  ipv6 source-guard policy example_policy

    Specifies the IPv6 Source Guard policy name and enters IPv6 Source Guard policy configuration mode.

    Step 4

    [deny global-autoconf] [permit link-local] [default{. . . }] [exit] [no{. . . }]

    Example:

    Switch(config-sisf-sourceguard)#  deny global-autoconf

    (Optional) Defines the IPv6 Source Guard policy.

    • deny global-autoconf—Denies data traffic from auto-configured global addresses. This is useful when all global addresses on a link are DHCP-assigned and the administrator wants to block hosts with self-configured addresses to send traffic.

    • permit link-local—Allows all data traffic that is sourced by a link-local address.
    Note 

    Trusted option under source guard policy is not supported.

    Step 5

    end

    Example:

    Switch(config-sisf-sourceguard)# end

    Exits out of IPv6 Source Guard policy configuration mode.

    Step 6

    show ipv6 source-guard policy policy_name

    Example:

    Switch# show ipv6 source-guard policy example_policy

    Shows the policy configuration and all the interfaces where the policy is applied.

    What to do next

    Apply the IPv6 Source Guard policy to an interface.

    How to Attach an IPv6 Source Guard Policy to an Interface

    Procedure

      Command or Action Purpose
    Step 1

    enable

    Example:

    
Switch> enable

    Enables privileged EXEC mode.

    • Enter your password if prompted.

    Step 2

    configure terminal

    Example:

    Switch# configure terminal

    Enters the global configuration mode.

    Step 3

    interface Interface_type stack/module/port

    Example:

    Switch(config)#  interface gigabitethernet 1/1/4

    Specifies an interface type and identifier; enters the interface configuration mode.

    Step 4

    ipv6 source-guard [ attach-policy <policy_name> ]

    Example:

    Switch(config-if)# ipv6 source-guard attach-policy example_policy

    Attaches the IPv6 Source Guard policy to the interface. The default policy is attached if the attach-policy option is not used.

    Step 5

    show ipv6 source-guard policy policy_name

    Example:

    Switch#(config-if)# show ipv6 source-guard policy example_policy

    Shows the policy configuration and all the interfaces where the policy is applied.

    How to Configure IPv6 Source Guard

    Procedure

      Command or Action Purpose
    Step 1

    enable

    Example:

    
Switch> enable

    Enables privileged EXEC mode.

    • Enter your password if prompted.

    Step 2

    configure terminal

    Example:

    Switch# configure terminal

    Enters the global configuration mode.

    Step 3

    [no] ipv6 source-guard policy policy_name

    Example:

    Switch(config)#  ipv6 source-guard policy example_policy

    Specifies the IPv6 Source Guard policy name and enters IPv6 Source Guard policy configuration mode.

    Step 4

    [deny global-autoconf] [permit link-local] [default{. . . }] [exit] [no{. . . }]

    Example:

    Switch(config-sisf-sourceguard)#  deny global-autoconf

    (Optional) Defines the IPv6 Source Guard policy.

    • deny global-autoconf—Denies data traffic from auto-configured global addresses. This is useful when all global addresses on a link are DHCP-assigned and the administrator wants to block hosts with self-configured addresses to send traffic.

    • permit link-local—Allows all data traffic that is sourced by a link-local address.
    Note 

    Trusted option under source guard policy is not supported.

    Step 5

    end

    Example:

    Switch(config-sisf-sourceguard)# end

    Exits out of IPv6 Source Guard policy configuration mode.

    Step 6

    show ipv6 source-guard policy policy_name

    Example:

    Switch# show ipv6 source-guard policy example_policy

    Shows the policy configuration and all the interfaces where the policy is applied.

    What to do next

    Apply the IPv6 Source Guard policy to an interface.

    How to Attach an IPv6 Source Guard Policy to an Interface

    Procedure

      Command or Action Purpose
    Step 1

    enable

    Example:

    
Switch> enable

    Enables privileged EXEC mode.

    • Enter your password if prompted.

    Step 2

    configure terminal

    Example:

    Switch# configure terminal

    Enters the global configuration mode.

    Step 3

    interface Interface_type stack/module/port

    Example:

    Switch(config)#  interface gigabitethernet 1/1/4

    Specifies an interface type and identifier; enters the interface configuration mode.

    Step 4

    ipv6 source-guard [ attach-policy <policy_name> ]

    Example:

    Switch(config-if)# ipv6 source-guard attach-policy example_policy

    Attaches the IPv6 Source Guard policy to the interface. The default policy is attached if the attach-policy option is not used.

    Step 5

    show ipv6 source-guard policy policy_name

    Example:

    Switch#(config-if)# show ipv6 source-guard policy example_policy

    Shows the policy configuration and all the interfaces where the policy is applied.

    How to attach an IPv6 Source Guard Policy to a Layer 2 EtherChannel Interface

    Procedure

      Command or Action Purpose
    Step 1

    enable

    Example:

    
Device> enable

    Enables privileged EXEC mode.

    • Enter your password if prompted.

    Step 2

    configure terminal

    Example:

    Device# configure terminal

    Enters the global configuration mode.

    Step 3

    interface port-channel port-channel-number

    Example:

    Device (config)# interface Po4

    Specifies an interface type and port number and places the switch in the port channel configuration mode.

    Step 4

    ipv6 source-guard [ attach-policy <policy_name> ]

    Example:

    Device(config-if) # ipv6 source-guard attach-policy example_policy

    Attaches the IPv6 Source Guard policy to the interface. The default policy is attached if the attach-policy option is not used.

    Step 5

    show ipv6 source-guard policy policy_name

    Example:

    Device(config-if) #show ipv6 source-guard policy example_policy

    Shows the policy configuration and all the interfaces where the policy is applied.

    How to Configure IPv6 Prefix Guard


    Note

    To allow routing protocol control packets sourced by a link-local address when prefix guard is applied, enable the permit link-local command in the source-guard policy configuration mode.

    Procedure

      Command or Action Purpose
    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

    [ no] ipv6 source-guard policy source-guard-policy

    Example:

    Device(config)# ipv6 source-guard policy my_snooping_policy

    Defines an IPv6 source-guard policy name and enters switch integrated security features source-guard policy configuration mode.

    Step 4

    [ no ] validate address

    Example:

    Device(config-sisf-sourceguard)# no validate address

    Disables the validate address feature and enables the IPv6 prefix guard feature to be configured.

    Step 5

    validate prefix

    Example:

    Device(config-sisf-sourceguard)# validate prefix

    Enables IPv6 source guard to perform the IPv6 prefix-guard operation.

    Step 6

    exit

    Example:

    Device(config-sisf-sourceguard)# exit

    Exits switch integrated security features source-guard policy configuration mode and returns to privileged EXEC mode.

    Step 7

    show ipv6 source-guard policy [ source-guard-policy]

    Example:

    Device# show ipv6 source-guard policy policy1

    Displays the IPv6 source-guard policy configuration.

    How to Attach an IPv6 Prefix Guard Policy to an Interface

    Procedure

      Command or Action Purpose
    Step 1

    enable

    Example:

    
Switch> enable

    Enables privileged EXEC mode.

    • Enter your password if prompted.

    Step 2

    configure terminal

    Example:

    Switch# configure terminal

    Enters the global configuration mode.

    Step 3

    interface Interface_type stack/module/port

    Example:

    Switch(config)#  interface gigabitethernet 1/1/4

    Specifies an interface type and identifier; enters the interface configuration mode.

    Step 4

    ipv6 source-guard attach-policy policy_name

    Example:

    Switch(config-if)# ipv6 source-guard attach-policy example_policy

    Attaches the IPv6 Source Guard policy to the interface. The default policy is attached if the attach-policy option is not used.

    Step 5

    show ipv6 source-guard policy policy_name

    Example:

    Switch(config-if)# show ipv6 source-guard policy example_policy

    Shows the policy configuration and all the interfaces where the policy is applied.

    How to attach an IPv6 Prefix Guard Policy to a Layer 2 EtherChannel Interface

    Procedure

      Command or Action Purpose
    Step 1

    enable

    Example:

    
Device> enable

    Enables privileged EXEC mode.

    • Enter your password if prompted.

    Step 2

    configure terminal

    Example:

    Device# configure terminal

    Enters the global configuration mode.

    Step 3

    interface port-channel port-channel-number

    Example:

    Device (config)# interface Po4

    Specifies an interface type and port number and places the switch in the port channel configuration mode.

    Step 4

    ipv6 source-guard [ attach-policy <policy_name> ]

    Example:

    Device(config-if)# ipv6 source-guard attach-policy example_policy

    Attaches the IPv6 Source Guard policy to the interface. The default policy is attached if the attach-policy option is not used.

    Step 5

    show ipv6 source-guard policy policy_name

    Example:

    Device(config-if)# show ipv6 source-guard policy example_policy

    Shows the policy configuration and all the interfaces where the policy is applied.