Prerequisites for IPv6 First Hop Security
You have configured the necessary IPv6 enabled SDM template.
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You have configured the necessary IPv6 enabled SDM template.
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.
IPv6 FHS is composed of the following IPv6 security features: IPv6 Snooping, IPv6 Neighbor Discovery Inspection, IPv6 Router Advertisement Guard , IPv6 DHCP Guard, IPv6 Source Guard, IPv6 Prefix Guard, IPv6 Destination Guard.
Each one of these security features addresses a different aspect of first hop security. In order to use a security feature, the corresponding policy must be configured. Policies specify a particular behavior. They must also be attached to a target, which can be a physical interface, an EtherChannel 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, and applied as specified.
In addition to the security features, the IPv6 FHS infrastructure has an IPv6 FHS Binding Table, which is a database table of IPv6 neighbors connected to the device. A binding entry includes information such as the IP and MAC address of the host, the interface, VLAN, state of the entry etc. This database or binding table is used by other 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. The binding table is updated through the IPv6 Snooping feature, and through manually added static binding entries.
![]() Note |
The IPv6 FHS Binding Table is supported through the Switch Integrated Security Feature (SISF) feature. For more information, see the Configuring Switch Integrated Security Features chapter in this guide. |
![]() Note |
The IPv6 Snooping feature is deprecated and the SISF feature replaces it and offers the same capabilities. While the IPv6 Snooping commands are still available on the CLI and the existing configuration continues to be supported, the commands will be removed from the CLI in a later release. For more information about the replacement feature, see the Configuring Switch Integrated Security Features chapter in this guide. |
IPv6 Snooping acts as a container that enables most of the features available with FHS in IPv6 including following capabilities and functions:
Neighbor Discovery Snooping: IPv6 Neighbor Discovery Snooping analyzes and verifies IPv6 Neighbor Discovery Protocol (NDP) traffic. During inspection, it gleans address bindings (IP, MAC, port, etc) and stores it in the binding table.
DHCPv6 Snooping: DHCPv6 Snooping traps DHCPv6 packets between DHCPv6 Client and DHCPv6 Server. From the packets snooped, assigned addresses are learnt and stored in the binding table.
Device tracking: IPv6 Snooping also tracks the movement of hosts from one port to another, verifies their existence using Duplicate Address Detection (DAD).
With the IPv6 Snooping feature one can limit the number of addresses any node on the link can claim. This feature can be used to protect the switch binding table against denial of service flooding attacks.
By default, a snooping policy has a security-level of guard. When 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 device or DHCP server or 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. This is a less preferable option, because the benefits of FHS features are not effective.
To use this feature, configure an IPv6 Snooping policy and attach it to a target. See Configuring an IPv6 Snooping Policy.
![]() Note |
Starting with Cisco IOS XE Amsterdam 17.1.1, the IPv6 Neighbor Discovery Inspection (IPv6 ND Inspection) feature is deprecated and the SISF feature replaces it and offers the same capabilities. While the IPv6 ND Inspection commands are still available on the CLI and the existing configuration continues to be supported, the commands will be removed from the CLI in a later release. For more information about the replacement feature, see the Configuring Switch Integrated Security Features chapter in this guide. |
The IPv6 ND Inspection feature learns and secures bindings for stateless auto-configuration addresses in Layer 2 neighbor tables. It analyzes neighbor discovery messages in order to build a trusted binding table database. IPv6 neighbor discovery messages that do not conform are dropped. An neighbor discovery message is considered trustworthy if its IPv6-to-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.
To use this feature, configure an IPv6 ND Inspection policy and attach it to a target. See Configuring an IPv6 Neighbor Discovery Inspection Policy.
This feature enables the network administrator to block or reject unwanted or rogue Router Advertisement (RA) guard messages that arrive at the network device platform. RAs are used by devices to announce themselves on the link. The RA Guard feature analyzes the RAs and filters out bogus RAs sent by unauthorized devices. 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.
SISF-based device-tracking forwards router solicitation packets only on interfaces that have the RA guard policy configured and are also designated as router-facing interfaces. If no such interface exists, the router solicitation messages are dropped, which might delay the router discovery for onboarding hosts as they will be unable to discover the router until it sends a periodic unsolicited router advertisement.
To use this feature, configure an IPv6 RA Guard policy and attach it to a target. See Configuring an IPv6 Router Advertisement Guard Policy.
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 an IPv6 DHCP Guard policy and attach it to a target. See Configuring an IPv6 DHCP Guard Policy.
To debug DHCP guard packets, use the debug ipv6 snooping dhcp-guard privileged EXEC command.
The IPv6 Source Guard feature validates the source of IPv6 traffic to prevent source address spoofing. It deals exclusively with data packet traffic. You can use this feature to deny traffic from unknown sources, traffic from sources not assigned by a DHCP server, etc.
It involves a hardware-programmed (TCAM table) filter which allows or denies traffic based on its source address. For the filter to work this way, an entry (of the source address) in the binding table is required. If the source address is in the binding table, the filter allows the packet into the network; if the address is not in the binding table, entry is denied and the packet is dropped. When an entry is removed from the binding table, the filter is also removed, and subsequent packets with that source address are dropped.
When configuring this feature, consider the following:
The IPv6 Source Guard and Prefix Guard features are supported only in the ingress direction and not supported in the egress direction.
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 or Prefix Guard cannot be applied together.
IPv6 Source Guard and Prefix Guard is supported on EtherChannels
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 command instead of ip verify source tracking mac-check command. 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).
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.
Binding information is normally gleaned from IPv6 NDP traffic and DHCP packets. If you rely only on a DHCP server for source addresses of hosts, ensure that you also configure a data-glean recovery function to counteract a situation where entries are prematurely removed from the binding table (for various reasons) before the DHCP lease timer expires. This way, the recovery function restores binding entries of valid hosts and you can be sure that that the IPv6 Source Guard feature allows only packets with a DHCP server-assigned source address. See Example: Using the Data-Glean Recovery Function.
To use this feature, you must configure an IPv6 Source Guard policy and attach it to a target. See Configuring IPv6 Source Guard .
To debug source-guard packets, use the debug ipv6 snooping source-guard privileged EXEC command.
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.
In order to use this feature, you must configure an IPv6 Prefix Guard policy and attach it to a target. See Configuring IPv6 Prefix Guard.
![]() Note |
Ensure that you have read the configuration considerations listed in the IPv6 Source Guard section above - some of them apply to the IPv6 Prefix Guard feature as well. |
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.
![]() Note |
We recommend that you apply an IPv6 Destination Guard policy on all Layer 2 VLANs with an SVI configured. |
In order to use this feature, you must configure an IPv6 Destination Guard policy and attach it to a target. See Configuring an IPv6 Destination Guard Policy.
![]() Note |
The IPv6 Snooping Policy feature has been deprecated. Although the commands are visible on the CLI and you can configure them, we recommend that you use the Switch Integrated Security Feature (SISF)-based Device Tracking feature instead. |
Beginning in privileged EXEC mode, follow these steps to configure IPv6 Snooping Policy :
Command or Action | Purpose | |
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Step 1 |
enable Example:
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Enables privileged EXEC mode. Enter your password if prompted. |
Step 2 |
configure terminal Example:
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Enters global configuration mode. |
Step 3 |
ipv6 snooping policy policy-name Example:
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Creates a snooping policy and enters IPv6 snooping policy configuration mode. |
Step 4 |
{[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:
Example:
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Enables data address gleaning, validates messages against various criteria, specifies the security level for messages.
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Step 5 |
end Example:
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Exits IPv6 snooping policy configuration mode and returns to privileged EXEC mode. |
Step 6 |
show ipv6 snooping policy policy-name Example:
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Displays the snooping policy configuration. |
Attach an IPv6 Snooping policy to interfaces or VLANs.
Beginning in privileged EXEC mode, follow these steps to attach an IPv6 Snooping policy on an interface or VLAN:
Command or Action | Purpose | |||
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Step 1 |
enable Example:
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Enables privileged EXEC mode. Enter your password if prompted. |
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Step 2 |
configure terminal Example:
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Enters global configuration mode. |
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Step 3 |
interface interface_type stack/module/port Example:
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Specifies an interface type and identifier and enters the interface configuration mode. |
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Step 4 |
switchport Example:
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Enters the Switchport mode.
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Step 5 |
ipv6 snooping [attach-policy policy_name [ vlan {vlan_id | add vlan_ids | except vlan_ids | none | remove vlan_ids}] | vlan {vlan_id | add vlan_ids | except vlan_ids | none | remove vlan_ids | all} ] Example:
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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. |
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Step 6 |
end Example:
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Exits interface configuration mode and returns to privileged EXEC mode. |
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Step 7 |
show running-config Example:
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Verifies that the policy is attached to the specified interface without exiting the interface configuration mode. |
Beginning in privileged EXEC mode, follow these steps to attach an IPv6 Snooping policy on an EtherChannel interface or VLAN:
Command or Action | Purpose | |||
---|---|---|---|---|
Step 1 |
enable Example:
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Enables privileged EXEC mode. Enter your password if prompted. |
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Step 2 |
configure terminal Example:
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Enters global configuration mode. |
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Step 3 |
interface range interface_name Example:
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Specifies the port-channel interface name assigned when the EtherChannel was created. Enters the interface range configuration mode.
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Step 4 |
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:
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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. |
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Step 5 |
end Example:
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Exits interface range configuration mode and returns to privileged EXEC mode. |
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Step 6 |
show running-config interfaceportchannel_interface_name Example:
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Confirms that the policy is attached to the specified interface. |
Beginning in privileged EXEC mode, follow these steps to attach an IPv6 Snooping Policy to VLANs across multiple interfaces:
Command or Action | Purpose | |
---|---|---|
Step 1 |
enable Example:
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Enables privileged EXEC mode. Enter your password if prompted. |
Step 2 |
configure terminal Example:
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Enters global configuration mode. |
Step 3 |
vlan configuration vlan_list Example:
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Specifies the VLANs to which the IPv6 Snooping policy will be attached, and enters the VLAN interface configuration mode. |
Step 4 |
ipv6 snooping [attach-policy policy_name] Example:
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Attaches the IPv6 Snooping policy to the specified VLANs across all device 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 5 |
end Example:
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Exits VLAN interface configuration mode and returns to privileged EXEC mode. |
Beginning in privileged EXEC mode, follow these steps to configure IPv6 Binding Table Content :
Command or Action | Purpose | |
---|---|---|
Step 1 |
enable Example:
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Enables privileged EXEC mode. Enter your password if prompted. |
Step 2 |
configure terminal Example:
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Enters global configuration mode. |
Step 3 |
[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:
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Adds a static entry to the binding table database. |
Step 4 |
[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:
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Specifies the maximum number of entries that are allowed to be inserted in the binding table cache. |
Step 5 |
ipv6 neighbor binding logging Example:
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Enables the logging of binding table main events. |
Step 6 |
exit Example:
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Exits global configuration mode and returns to privileged EXEC mode. |
Step 7 |
show ipv6 neighbor binding Example:
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Displays contents of a binding table. |
Starting with Cisco IOS XE Amsterdam 17.1.1 the IPv6 ND Inspection feature is deprecated and the SISF- based device tracking feature replaces it and offers the same capabilities. For the corresponding replacement task, see Creating a Custom Device Tracking Policy with Custom Settings under the Configuring SISF-Based Device Tracking chapter in this document.
Beginning in privileged EXEC mode, follow these steps to configure an IPv6 ND Inspection Policy:
Command or Action | Purpose | |
---|---|---|
Step 1 |
enable Example:
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Enables privileged EXEC mode. Enter your password if prompted. |
Step 2 |
configure terminal Example:
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Enters global configuration mode. |
Step 3 |
ipv6 nd inspection policy policy-name Example:
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Specifies the ND inspection policy name and enters ND Inspection Policy configuration mode. |
Step 4 |
device-role {host | switch} Example:
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Specifies the role of the device attached to the port. The default is host. |
Step 5 |
limit address-count value Example:
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Limits the number of IPv6 addresses allowed to be used on the port. |
Step 6 |
tracking {enable [reachable-lifetime {value | infinite}] | disable [stale-lifetime {value | infinite}]} Example:
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Overrides the default tracking policy on a port. |
Step 7 |
trusted-port Example:
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Configures a port to become a trusted port. |
Step 8 |
validate source-mac Example:
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Checks the source media access control (MAC) address against the link-layer address. |
Step 9 |
no {device-role | limit address-count | tracking | trusted-port | validate source-mac} Example:
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Removes the current configuration of a parameter with the no form of the command. |
Step 10 |
default {device-role | limit address-count | tracking | trusted-port | validate source-mac} Example:
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Restores configuration to the default values. |
Step 11 |
end Example:
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Exits ND Inspection Policy configuration mode and returns to privileged EXEC mode. |
Step 12 |
show ipv6 nd inspection policy policy_name Example:
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Verifies the ND inspection configuration. |
Starting with Cisco IOS XE Amsterdam 17.1.1 the IPv6 ND Inspection feature is deprecated and the SISF- based device tracking feature replaces it and offers the same capabilities. For the corresponding replacement task, see Attaching a Device Tracking Policy to an Interface under the Configuring SISF-Based Device Tracking chapter in this document.
Beginning in privileged EXEC mode, follow these steps to attach an IPv6 ND Inspection policy to an interface or VLANs on an interface :
Command or Action | Purpose | |
---|---|---|
Step 1 |
enable Example:
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Enables privileged EXEC mode. Enter your password if prompted. |
Step 2 |
configure terminal Example:
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Enters global configuration mode. |
Step 3 |
interface interface-type interface-number Example:
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Specifies an interface type and identifier; enters the interface configuration mode. |
Step 4 |
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:
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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 5 |
end Example:
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Exits interface configuration mode and returns to privileged EXEC mode. |
Starting with Cisco IOS XE Amsterdam 17.1.1 the IPv6 ND Inspection feature is deprecated and the SISF- based device tracking feature replaces it and offers the same capabilities. For the corresponding replacement task, see Attaching a Device Tracking Policy to an Interface under the Configuring SISF-Based Device Tracking chapter in this document.
Beginning in privileged EXEC mode, follow these steps to attach an IPv6 Neighbor Discovery Inspection policy on an EtherChannel interface or VLAN:
Command or Action | Purpose | |||
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Step 1 |
enable Example:
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Enables privileged EXEC mode. Enter your password if prompted. |
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Step 2 |
configure terminal Example:
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Enters global configuration mode. |
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Step 3 |
interface range interface_name Example:
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Specifies the port-channel interface name assigned when the EtherChannel was created. Enters interface range configuration mode.
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Step 4 |
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:
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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. |
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Step 5 |
end Example:
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Exits interface range configuration mode and returns to privileged EXEC mode. |
Starting with Cisco IOS XE Amsterdam 17.1.1 the IPv6 ND Inspection feature is deprecated and the SISF- based device tracking feature replaces it and offers the same capabilities. For the corresponding replacement task, see Attaching a Device Tracking Policy to a VLAN under the Configuring SISF-Based Device Tracking chapter in this document.
Beginning in privileged EXEC mode, follow these steps to attach an IPv6 ND Inspection policy to VLANs across multiple interfaces:
Command or Action | Purpose | |
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Step 1 |
enable Example:
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Enables privileged EXEC mode. Enter your password if prompted. |
Step 2 |
configure terminal Example:
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Enters global configuration mode. |
Step 3 |
vlan configuration vlan_list Example:
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Specifies the VLANs to which the IPv6 Snooping policy will be attached, and enters VLAN interface configuration mode. |
Step 4 |
ipv6 nd inspection [attach-policy policy_name] Example:
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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 5 |
end Example:
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Exits VLAN interface configuration mode and returns to privileged EXEC mode. |
Beginning in privileged EXEC mode, follow these steps to configure an IPv6 Router Advertisement policy :
Command or Action | Purpose | |||
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Step 1 |
enable Example:
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Enables privileged EXEC mode. Enter your password, if prompted. |
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Step 2 |
configure terminal Example:
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Enters global configuration mode. |
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Step 3 |
ipv6 nd raguard policy policy-name Example:
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Specifies the RA guard policy name and enters RA guard policy configuration mode. |
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Step 4 |
[no]device-role {host | monitor | router | switch} Example:
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Specifies the role of the device attached to the port. The default is host.
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Step 5 |
hop-limit {maximum | minimum} value Example:
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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. (1–255) Range for Maximum and Minimum Hop Limit values. 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. |
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Step 6 |
managed-config-flag {off | on} Example:
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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. |
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Step 7 |
match {ipv6 access-list list | ra prefix-list list} Example:
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Matches a specified prefix list or access list. |
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Step 8 |
other-config-flag {on | off} Example:
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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. |
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Step 9 |
[no]router-preference maximum {high | medium | low} Example:
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Enables filtering of Router Advertisement messages by the router preference flag. If not configured, this filter is disabled.
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Step 10 |
trusted-port Example:
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When configured as a trusted port, all attached devices are trusted, and no further message verification is performed. |
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Step 11 |
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:
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Restores a command to its default value. |
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Step 12 |
end Example:
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Exits RA Guard policy configuration mode and returns to privileged EXEC mode. |
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Step 13 |
show ipv6 nd raguard policy policy_name Example:
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(Optional) Displays the ND guard policy configuration. |
Beginning in privileged EXEC mode, follow these steps to attach an IPv6 Router Advertisement policy to an interface or to VLANs on the interface :
Command or Action | Purpose | |
---|---|---|
Step 1 |
enable Example:
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Enables privileged EXEC mode. Enter your password, if prompted. |
Step 2 |
configure terminal Example:
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Enters global configuration mode. |
Step 3 |
interface type number Example:
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Specifies an interface type and identifier; enters the interface configuration mode. |
Step 4 |
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:
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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 5 |
end Example:
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Exits interface configuration mode and returns to privileged EXEC mode. |
Beginning in privileged EXEC mode, follow these steps to attach an IPv6 Router Advertisement Guard Policy on an EtherChannel interface or VLAN:
Command or Action | Purpose | |||
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Step 1 |
enable Example:
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Enables privileged EXEC mode. Enter your password, if prompted. |
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Step 2 |
configure terminal Example:
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Enters global configuration mode. |
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Step 3 |
interface range type number Example:
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Specifies the port-channel interface name assigned when the EtherChannel was created. Enters interface range configuration mode.
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Step 4 |
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:
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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. |
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Step 5 |
end Example:
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Exits interface range configuration mode and returns to privileged EXEC mode. |
Beginning in privileged EXEC mode, follow these steps to attach an IPv6 Router Advertisement policy to VLANs regardless of interface:
Command or Action | Purpose | |
---|---|---|
Step 1 |
enable Example:
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Enables privileged EXEC mode. Enter your password, if prompted. |
Step 2 |
configure terminal Example:
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Enters global configuration mode. |
Step 3 |
vlan configuration vlan_list Example:
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Specifies the VLANs to which the IPv6 RA Guard policy will be attached, and enters VLAN interface configuration mode. |
Step 4 |
ipv6 dhcp guard [attach-policy policy_name] Example:
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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 5 |
end Example:
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Exits VLAN interface configuration mode and returns to privileged EXEC mode. |
Beginning in privileged EXEC mode, follow these steps to configure an IPv6 DHCP (DHCPv6) Guard policy:
Command or Action | Purpose | |||
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Step 1 |
enable Example:
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Enables privileged EXEC mode. Enter your password, if prompted. |
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Step 2 |
configure terminal Example:
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Enters global configuration mode. |
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Step 3 |
ipv6 dhcp guard policy policy-name Example:
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Specifies the DHCPv6 Guard policy name and enters DHCPv6 Guard Policy configuration mode. |
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Step 4 |
device-role {client | server} Example:
|
(Optional) Filters out DHCPv6 replies and DHCPv6 advertisements on the port that are not from a device of the specified role. Default is client.
|
||
Step 5 |
match server access-list ipv6-access-list-name Example:
|
(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 6 |
match reply prefix-list ipv6-prefix-list-name Example:
|
(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 7 |
preference{ max limit | min limit } Example:
|
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 8 |
trusted-port Example:
|
(Optional) trusted-port—Sets the port to a trusted mode. No further policing takes place on the port.
|
||
Step 9 |
default {device-role | trusted-port} Example:
|
(Optional) default—Sets a command to its defaults. |
||
Step 10 |
end Example:
|
Exits DHCPv6 Guard Policy configuration mode and returns to privileged EXEC mode. |
||
Step 11 |
show ipv6 dhcp guard policy policy_name Example:
|
(Optional) Displays the configuration of the IPv6 DHCP guard policy. Omitting the policy_name variable displays all DHCPv6 policies. |
Beginning in privileged EXEC mode, follow these steps to configure IPv6 Binding Table Content :
Command or Action | Purpose | |
---|---|---|
Step 1 |
enable Example:
|
Enables privileged EXEC mode. Enter your password, if prompted. |
Step 2 |
configure terminal Example:
|
Enters global configuration mode. |
Step 3 |
interface type number Example:
|
Specifies an interface type and identifier, and enters interface configuration mode. |
Step 4 |
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:
|
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 5 |
end Example:
|
Exits interface configuration mode and returns to privileged EXEC mode. |
Beginning in privileged EXEC mode, follow these steps to attach an IPv6 DHCP Guard policy on an EtherChannel interface or VLAN:
Command or Action | Purpose | |||
---|---|---|---|---|
Step 1 |
enable Example:
|
Enables privileged EXEC mode. Enter your password, if prompted. |
||
Step 2 |
configure terminal Example:
|
Enters global configuration mode. |
||
Step 3 |
interface range Interface_name Example:
|
Specify the port-channel interface name assigned when the EtherChannel was created. Enters interface range configuration mode.
|
||
Step 4 |
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:
|
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 5 |
end Example:
|
Exits interface range configuration mode and returns to privileged EXEC mode. |
Beginning in privileged EXEC mode, follow these steps to attach an IPv6 DHCP Guard policy to VLANs across multiple interfaces:
Command or Action | Purpose | |
---|---|---|
Step 1 |
enable Example:
|
Enables privileged EXEC mode. Enter your password, if prompted. |
Step 2 |
configure terminal Example:
|
Enters global configuration mode. |
Step 3 |
vlan configuration vlan_list Example:
|
Specifies the VLANs to which the IPv6 Snooping policy will be attached, and enters VLAN interface configuration mode. |
Step 4 |
ipv6 dhcp guard [attach-policy policy_name] Example:
|
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 5 |
end Example:
|
Exits VLAN interface configuration mode and returns to privileged EXEC mode. |
Command or Action | Purpose | |||
---|---|---|---|---|
Step 1 |
enable Example:
|
Enables privileged EXEC mode. Enter your password, if prompted. |
||
Step 2 |
configure terminal Example:
|
Enters global configuration mode. |
||
Step 3 |
ipv6 source-guard policy policy_name Example:
|
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:
|
(Optional) Defines the IPv6 Source Guard policy.
|
||
Step 5 |
end Example:
|
Exits of IPv6 Source Guard policy configuration mode and returns to privileged EXEC mode. |
||
Step 6 |
show ipv6 source-guard policy policy_name Example:
|
Shows the policy configuration and all the interfaces where the policy is applied. |
Apply the IPv6 Source Guard policy to an interface.
Command or Action | Purpose | |
---|---|---|
Step 1 |
enable Example:
|
Enables privileged EXEC mode. Enter your password, if prompted. |
Step 2 |
configure terminal Example:
|
Enters global configuration mode. |
Step 3 |
interface type number Example:
|
Specifies an interface type and identifier; enters interface configuration mode. |
Step 4 |
ipv6 source-guard [ attach-policy <policy_name> ] Example:
|
Attaches the IPv6 Source Guard policy to the interface. The default policy is attached if the attach-policy option is not used. |
Step 5 |
end Example:
|
Exits interface configuration mode and returns to privileged EXEC mode. |
Step 6 |
show ipv6 source-guard policy policy_name Example:
|
Shows the policy configuration and all the interfaces where the policy is applied. |
Command or Action | Purpose | |
---|---|---|
Step 1 |
enable Example:
|
Enables privileged EXEC mode. Enter your password, if prompted. |
Step 2 |
configure terminal Example:
|
Enters global configuration mode. |
Step 3 |
interface port-channel port-channel-number Example:
|
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:
|
Attaches the IPv6 Source Guard policy to the interface. The default policy is attached if the attach-policy option is not used. |
Step 5 |
end Example:
|
Exits interface configuration mode and returns to privileged EXEC mode. |
Step 6 |
show ipv6 source-guard policy policy_name Example:
|
Shows the policy configuration and all the interfaces where the policy is applied. |
![]() 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. |
Command or Action | Purpose | |
---|---|---|
Step 1 |
enable Example:
|
Enables privileged EXEC mode. Enter your password, if prompted. |
Step 2 |
configure terminal Example:
|
Enters global configuration mode. |
Step 3 |
ipv6 source-guard policy source-guard-policy Example:
|
Defines an IPv6 source-guard policy name and enters switch integrated security features source-guard policy configuration mode. |
Step 4 |
validate address Example:
|
Disables the validate address feature and enables the IPv6 prefix guard feature to be configured. |
Step 5 |
validate prefix Example:
|
Enables IPv6 source guard to perform the IPv6 prefix-guard operation. |
Step 6 |
exit Example:
|
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:
|
Displays the IPv6 source-guard policy configuration. |
Command or Action | Purpose | |
---|---|---|
Step 1 |
enable Example:
|
Enables privileged EXEC mode. Enter your password, if prompted. |
Step 2 |
configure terminal Example:
|
Enters global configuration mode. |
Step 3 |
interface type number Example:
|
Specifies an interface type and identifier, and enters interface configuration mode. |
Step 4 |
ipv6 source-guard attach-policy policy_name Example:
|
Attaches the IPv6 Source Guard policy to the interface. The default policy is attached if the attach-policy option is not used. |
Step 5 |
end Example:
|
Exits interface configuration mode and returns to privileged EXEC mode. |
Step 6 |
show ipv6 source-guard policy policy_name Example:
|
Shows the policy configuration and all the interfaces where the policy is applied. |
Command or Action | Purpose | |
---|---|---|
Step 1 |
enable Example:
|
Enables privileged EXEC mode. Enter your password, if prompted. |
Step 2 |
configure terminal Example:
|
Enters global configuration mode. |
Step 3 |
interface port-channel port-channel-number Example:
|
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:
|
Attaches the IPv6 Source Guard policy to the interface. The default policy is attached if the attach-policy option is not used. |
Step 5 |
end Example:
|
Exits interface configuration mode and returns to privileged EXEC mode. |
Step 6 |
show ipv6 source-guard policy policy_name Example:
|
Shows the policy configuration and all the interfaces where the policy is applied. |
Beginning in privileged EXEC mode, follow these steps to configure an IPv6 destination guard policy:
Command or Action | Purpose | |
---|---|---|
Step 1 |
enable Example:
|
Enables privileged EXEC mode. Enter your password, if prompted. |
Step 2 |
configure terminal Example:
|
Enters global configuration mode. |
Step 3 |
ipv6 destination-guard policy policy-name Example:
|
Defines the destination guard policy name and enters destination-guard configuration mode. |
Step 4 |
enforcement {always | stressed} Example:
|
Sets the enforcement level for the target address. |
Step 5 |
exit Example:
|
Exits destination-guard configuration mode and returns to global configuration mode. |
Step 6 |
interface type number Example:
|
Enters interface configuration mode. |
Step 7 |
ipv6 destination-guard attach-policy [policy-name] Example:
|
Attaches a destination guard policy to an interface. |
Step 8 |
end Example:
|
Exits interface configuration mode and returns to privileged EXEC configuration mode. |
Step 9 |
show ipv6 destination-guard policy [policy-name] Example:
|
(Optional) Displays the policy configuration and all interfaces where the policy is applied. |
Device> enable
Device# configure terminal
Device(config)# ipv6 access-list acl1
Device(config-ipv6-acl)# permit host 2001:DB8:0000:
0000:0000:0000:0000:0001 any
Device(config-ipv6-acl)# exit
Device(config)# ipv6 prefix-list abc permit 2001:0DB8::/64 le 128
Device(config)# ipv6 dhcp guard policy pol1
Device(config-dhcp-guard)# device-role server
Device(config-dhcp-guard)# match server access-list acl1
Device(config-dhcp-guard)# match reply prefix-list abc
Device(config-dhcp-guard)# preference min 0
Device(config-dhcp-guard)# preference max 255
Device(config-dhcp-guard)# trusted-port
Device(config-dhcp-guard)# exit
Device(config)# interface GigabitEthernet 0/2/0
Device(config-if)# switchport
Device(config-if)# ipv6 dhcp guard attach-policy pol1 vlan add 1
Device(config-if)# exit
Device(config)# vlan 1
Device(config-vlan)# ipv6 dhcp guard attach-policy pol1
Device(config-vlan)# end
The following example shows how to attach an IPv6 Source Guard Policy to a Layer 2 EtherChannel Interface:
Device> enable
Device# configure terminal
Device(config)# ipv6 source-guard policy POL
Device(config-sisf-sourceguard) # validate address
Device(config-sisf-sourceguard)# exit
Device(config)# interface Port-Channel 4
Device(config-if)# ipv6 snooping
Device(config-if)# ipv6 source-guard attach-policy POL
Device(config-if)# end
Device#
The following example shows how to attach an IPv6 Prefix Guard Policy to a Layer 2 EtherChannel Interface:
Device> enable
Device# configure terminal
Device(config)# ipv6 source-guard policy POL
Device (config-sisf-sourceguard)# no validate address
Device((config-sisf-sourceguard)# validate prefix
Device(config-sisf-sourceguard)# exit
Device(config)# interface Po4
Device(config-if)# ipv6 snooping
Device(config-if)# ipv6 source-guard attach-policy POL
Device(config-if)# end
Binding entries can be removed from the binding table for various reasons: the switch may have reset, or you may have used the clear commands, and so on. The following example shows how you can use the data-glean recovery function to restore valid binding entries in the binding table.
The scenario used in this example involves interaction between the IPv6 Source Guard, IEEE 802.1x authentication, and SISF-based device-tracking features. Described below is the set-up we are using for this example, along with sample configuration, followed by a description of situations that can cause premature removal of valid entries from the binding table, and finally, the configuration that you must have in-place, for such entries to be restored.
The key aspects of this example set-up are outlined below:
An IPv6 Source Guard policy is configured and attached to an interface.
Device# show ipv6 source-guard policy src-guard-policy
Source guard policy src-guard-policy configuration:
validate address
Policy src-guard-policy is applied on the following targets:
Target Type Policy Feature Target range
Gi1/0/1 PORT src-guard-policy Source guard vlan all
A custom SISF-based device-tracking policy, which allows gleaning of only DHCP packets and not NDP packets is attached to the same interface as the source guard policy.
This means that any host in the network can use only a DHCP-assigned IP address to communicate.
Device# show device-tracking policy glean_only_DHCP
Device-tracking policy glean_only_DHCP configuration:
security-level guard
device-role node
NOT gleaning from Neighbor Discovery
gleaning from DHCP6
NOT gleaning from ARP
NOT gleaning from DHCP4
NOT gleaning from protocol unkn
Policy glean_only_DHCP is applied on the following targets:
Target Type Policy Feature Target range
Gi1/0/1 PORT glean_only_DHCP Device-tracking vlan all
IEEE 802.1x authentication is enabled.
This means only authenticated hosts are allowed to request addresses from the DHCP server and attach themselves to the network.
![]() Note |
The following 802.1x configuration is for example purposes only. |
<output truncated>
interface GigabitEthernet 1/0/1
description 802.1x+MAB+IPT
authentication control-direction in
authentication event server dead action authorize vlan <vlan id>
authentication event no-response action authorize vlan <vlan id>
authentication event server alive action reinitialize
authentication host-mode multi-domain
authentication port-control auto
authentication periodic
authentication timer reauthenticate server
authentication violation protect
mab
trust device cisco-phone
dot1x pae authenticator
dot1x timeout quiet-period 30
dot1x timeout server-timeout 5
dot1x timeout tx-period 1
dot1x max-req 1
dot1x max-reauth-req 1
<output truncated>
Events that cause a change in the configuration occur in any typical network. For example, a host may be unplugged from one port and then plugged back into another port, or an interface may flap, or you may have configured the shutdown, followed by the no shutdown interface configuration commands. For the duration that the host is not connected, or the interface is down, the host or interface is considered "unauthenticated". Because of this absence of host or interface authentication, the corresponding binding table entry is removed from the binding table.
When such a host connects back to the network or when such an interface is restored, the client does not reinstantiate the DHCP sequence until the DHCP lease time expires. Until the DHCP sequence is reinstantiated, a valid address fails to be stored in the binding table. If the entry is not in the binding table, the IPv6 Source Guard’s filter function drops all packets initiated by that host.
In order to prevent such a situation, configure the data-glean recovery function.
To configure data-glean recovery, create a custom SISF-based device-tracking policy, configure the data-glean policy parameter to recover binding information from DHCP Server, and attach it to the necessary targets.
![]() Note |
When configuring data-glean recovery from DHCP, for binding information retrieval to work as expected, the DHCPv6 Leasequery configuration (as in RFC 5007), is required. Ensure that the leasequery configuration is enabled on the DHCP Server. |
glean_only_DHCP
), to recover binding information. It remains attached to the same target as the IPv6 Source Guard policy, that is, Gigabit
Ethernet 1/0/1:
Device# configure terminal
Device(config)# device-tracking policy glean_only_DHCP
Device(config-device-tracking)# data-glean recovery dhcp
Device(config-device-tracking)# exit
Device# show device-tracking policy glean_only_DHCP
Device-tracking policy glean_only_DHCP configuration:
security-level guard
device-role node
data-glean recovery dhcp <<< Recovery of binding information is configured.
NOT gleaning from Neighbor Discovery
gleaning from DHCP6
NOT gleaning from ARP
NOT gleaning from DHCP4
NOT gleaning from protocol unkn
Policy glean_only_DHCP is applied on the following targets:
Target Type Policy Feature Target range
Gi1/0/1 PORT glean_only_DHCP Device-tracking vlan all
Device# show device-tracking policies interface Gi1/0/1
Target Type Policy Feature Target range
Gi1/0/1 PORT glean_only_DHCP Device-tracking vlan all
Gi1/0/1 PORT src-guard-policy Source guard vlan all
With this additional configuration, valid entries are automatically restored in the binding table if they are removed prematurely.
Related Topic |
Document Title |
---|---|
SISF |
Configuring SISF-Based Device Tracking chapter of the Security Configuration Guide |
Description | Link |
---|---|
The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies. To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds. Access to most tools on the Cisco Support website requires a Cisco.com user ID and password. |
This table provides release and related information for features explained in this module.
These features are available on all releases subsequent to the one they were introduced in, unless noted otherwise.
Release |
Feature |
Feature Information |
---|---|---|
Cisco IOS XE Everest 16.5.1a |
IPv6 First Hop Security |
First Hop Security in IPv6 is a set of IPv6 security features, the policies of which can be attached to a physical interface, an EtherChannel 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 IPv6 Snooping Policy feature has been deprecated. Although the commands are visible on the CLI and you can configure them, we recommend that you use the Switch Integrated Security Feature (SISF)-based Device Tracking feature instead. |
Cisco IOS XE Amsterdam 17.1.1 |
IPv6 ND Inspection |
Starting with this release, the IPv6 ND Inspection feature is deprecated and the SISF- based device tracking feature replaces it and offers the same capabilities. While the IPv6 ND Inspection commands are still available on the CLI and the existing configuration continues to be supported, the commands will be removed from the CLI in a later release. For more information about the replacement feature, see the Configuring SISF-Based Device Tracking chapter in this guide. |
Use Cisco Feature Navigator to find information about platform and software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn.