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Access lists determine what traffic is blocked and what traffic is forwarded at device interfaces and allow filtering of traffic based on source and destination addresses, and inbound and outbound traffic to a specific interface. Standard IPv6 ACL functionality was extended to support traffic filtering based on IPv6 option headers and optional, upper-layer protocol type information for finer granularity of control. Standard IPv6 ACL functionality was extended to support traffic filtering based on IPv6 option headers and optional, upper-layer protocol type information for finer granularity of control.
This module describes how to configure IPv6 traffic filtering and to control access to virtual terminal lines.
The following are the prerequisites for IPV6 ACLs:
To use IPv6, you must configure the dual IPv4 and IPv6 Switch Database Management (SDM) template on the switch. You select the template by entering the sdm prefer {default | dual-ipv4-and-ipv6} global configuration command.
With IPv4, you can configure standard and extended numbered IP ACLs, named IP ACLs, and MAC ACLs. IPv6 supports only named ACLs.
The switch supports most Cisco IOS-supported IPv6 ACLs with some exceptions:
The switch does not support matching on these keywords: routing header, and undetermined-transport.
The switch does not support reflexive ACLs (the reflect keyword).
The switch does not support VLAN ACLs (VLAN maps) for IPv6.
Output router ACLs and input port ACLs for IPv6 are supported only on switch stacks. Switches support only control plane (incoming) IPv6 ACLs.
The switch does not apply MAC-based ACLs on IPv6 frames.
When configuring an ACL, there is no restriction on keywords entered in the ACL, regardless of whether or not they are supported on the platform. When you apply the ACL to an interface that requires hardware forwarding (physical ports or SVIs), the switch checks to determine whether or not the ACL can be supported on the interface. If not, attaching the ACL is rejected.
If an ACL is applied to an interface and you attempt to add an access control entry (ACE) with an unsupported keyword, the switch does not allow the ACE to be added to the ACL that is currently attached to the interface.
IPv6 ACLs on the switch have these characteristics:
Fragmented frames (the fragments keyword as in IPv4) are supported
The same statistics supported in IPv4 are supported for IPv6 ACLs.
If the switch runs out of hardware space, the packets associated with the ACL are dropped on the interface.
Routed or bridged packets with hop-by-hop options have IPv6 ACLs applied in software.
Logging is supported for router ACLs, but not for port ACLs.
The switch supports IPv6 address-matching for a full range of prefix-lengths.
You can filter IP version 6 (IPv6) traffic by creating IPv6 access control lists (ACLs) and applying them to interfaces similarly to the way that you create and apply IP version 4(IPv4) named ACLs. You can also create and apply input router ACLs to filter Layer 3 management traffic.
 Note |
To use IPv6, you must configure the dual IPv4 and IPv6 Switch Database Management (SDM) template on the switch. You select the template by entering the sdm prefer {default | dual-ipv4-and-ipv6} global configuration command. |
Packet filtering can help limit network traffic and restrict network use by certain users or devices. ACLs filter traffic as it passes through a router or switch and permit or deny packets crossing specified interfaces or VLANs. An ACL is a sequential collection of permit and deny conditions that apply to packets. When a packet is received on an interface, the switch compares the fields in the packet against any applied ACLs to verify that the packet has the required permissions to be forwarded, based on the criteria specified in the access lists. One by one, it tests packets against the conditions in an access list. The first match decides whether the switch accepts or rejects the packets. Because the switch stops testing after the first match, the order of conditions in the list is critical. If no conditions match, the switch rejects the packet. If there are no restrictions, the switch forwards the packet; otherwise, the switch drops the packet. The switch can use ACLs on all packets it forwards, including packets bridged within a VLAN.
You configure access lists on a router or Layer 3 switch to provide basic security for your network. If you do not configure ACLs, all packets passing through the switch could be allowed onto all parts of the network. You can use ACLs to control which hosts can access different parts of a network or to decide which types of traffic are forwarded or blocked at router interfaces. For example, you can allow e-mail traffic to be forwarded but not Telnet traffic. ACLs can be configured to block inbound traffic, outbound traffic, or both.
You can filter IP Version 6 (IPv6) traffic by creating IPv6 access control lists (ACLs) and applying them to interfaces similar to how you create and apply IP Version 4 (IPv4) named ACLs. You can also create and apply input router ACLs to filter Layer 3 management traffic when the switch is running IP base and LAN base feature sets.
A switch supports three types of IPv6 ACLs:
A switch supports two types of IPv6 ACLS:
IPv6 router ACLs are supported on outbound or inbound traffic on Layer 3 interfaces, which can be routed ports, switch virtual interfaces (SVIs), or Layer 3 EtherChannels. IPv6 router ACLs apply only to IPv6 packets that are routed.
IPv6 port ACLs are supported on outbound and inbound Layer 2 interfaces. IPv6 port ACLs are applied to all IPv6 packets entering the interface.
IPv6 router ACLs are supported on outbound or inbound traffic on Layer 3 interfaces, which can be routed ports, switch virtual interfaces (SVIs), or Layer 3 EtherChannels. IPv6 router ACLs apply only to IPv6 packets that are routed.
IPv6 port ACLs are supported on outbound and inbound Layer 2 interfaces. IPv6 port ACLs are applied to all IPv6 packets entering the interface.
VLAN ACLs or VLAN maps access-control all packets in a VLAN. You can use VLAN maps to filter traffic between devices in the same VLAN. ACL VLAN maps are applied on L2 VLANs. VLAN maps are configured to provide access control based on Layer 3 addresses for IPv6. Unsupported protocols are access-controlled through MAC addresses using Ethernet ACEs. After a VLAN map is applied to a VLAN, all packets entering the VLAN are checked against the VLAN map.
You can apply both IPv4 and IPv6 ACLs to an interface. As with IPv4 ACLs, IPv6 port ACLs take precedence over router ACLs.
The switch does not support VLAN ACLs (VLAN maps) for IPv6 traffic.
A switch image supports two types of IPv6 ACLs:
Note |
If you configure unsupported IPv6 ACLs, an error message appears and the configuration does not take affect. |
The switch does not support VLAN ACLs (VLAN maps) for IPv6 traffic.
You can apply both IPv4 and IPv6 ACLs to an interface.
As with IPv4 ACLs, IPv6 port ACLs take precedence over router ACLs:
When an input router ACL and input port ACL exist in an SVI, packets received on ports to which a port ACL is applied are filtered by the port ACL. Routed IP packets received on other ports are filtered by the router ACL. Other packets are not filtered.
When an output router ACL and input port ACL exist in an SVI, packets received on the ports to which a port ACL is applied are filtered by the port ACL. Outgoing routed IPv6 packets are filtered by the router ACL. Other packets are not filtered.
Note |
If any port ACL (IPv4, IPv6, or MAC) is applied to an interface, that port ACL is used to filter packets, and any router ACLs attached to the SVI of the port VLAN are ignored. |
If an IPv6 router ACL is configured to deny a packet, the packet is not routed. A copy of the packet is sent to the Internet Control Message Protocol (ICMP) queue to generate an ICMP unreachable message for the frame.
If a bridged frame is to be dropped due to a port ACL, the frame is not bridged.
You can create both IPv4 and IPv6 ACLs on a switch or switch stack, and you can apply both IPv4 and IPv6 ACLs to the same interface. Each ACL must have a unique name; an error message appears if you try to use a name that is already configured.
You use different commands to create IPv4 and IPv6 ACLs and to attach IPv4 or IPv6 ACLs to the same Layer 2 or Layer 3 interface. If you use the wrong command to attach an ACL (for example, an IPv4 command to attach an IPv6 ACL), you receive an error message.
You cannot use MAC ACLs to filter IPv6 frames. MAC ACLs can only filter non-IP frames.
If the hardware memory is full, packets are dropped on the interface and an unload error message is logged.
The default IPv6 ACL configuration is as follows:
Switch# show access-lists preauth_ipv6_acl
IPv6 access list preauth_ipv6_acl (per-user)
permit udp any any eq domain sequence 10
permit tcp any any eq domain sequence 20
permit icmp any any nd-ns sequence 30
permit icmp any any nd-na sequence 40
permit icmp any any router-solicitation sequence 50
permit icmp any any router-advertisement sequence 60
permit icmp any any redirect sequence 70
permit udp any eq 547 any eq 546 sequence 80
permit udp any eq 546 any eq 547 sequence 90
deny ipv6 any any sequence 100IPv6 ACLs on the switch have these characteristics:
Fragmented frames (the fragments keyword as in IPv4) are supported.
The same statistics supported in IPv4 are supported for IPv6 ACLs.
If the switch runs out of TCAM space, packets associated with the ACL label are forwarded to the CPU, and the ACLs are applied in software.
Routed or bridged packets with hop-by-hop options have IPv6 ACLs applied in software.
Logging is supported for router ACLs, but not for port ACLs.
The IPv6 PACL feature provides the ability to provide access control (permit or deny) on Layer 2 switch ports for IPv6 traffic. IPv6 PACLs are similar to IPv4 PACLs, which provide access control on Layer 2 switch ports for IPv4 traffic. They are supported only in the ingress direction and in hardware.
A PACL can filter ingress traffic on Layer 2 interfaces based on Layer 3 and Layer 4 header information or non-IP Layer 2 information.
The IPv6 ACL Extensions for Hop by Hop Filtering feature allows you to control IPv6 traffic that might contain hop-by-hop extension headers. You can configure an access control list (ACL) to deny all hop-by-hop traffic or to selectively permit traffic based on protocol.
IPv6 access control lists (ACLs) determine what traffic is blocked and what traffic is forwarded at device interfaces. ACLs allow filtering based on source and destination addresses, inbound and outbound to a specific interface. Use the ipv6 access-list command to define an IPv6 ACL, and the deny and permit commands to configure its conditions.
The IPv6 ACL Extensions for Hop by Hop Filtering feature implements RFC 2460 to support traffic filtering in any upper-layer protocol type.
How to Configure IPv6 ACLs
To filter IPv6 traffic, perform this procedure:
| Command or Action | Purpose | |
|---|---|---|
| Step 1 |
enable Example: |
Enables privileged EXEC mode.
|
| Step 2 |
configure terminal Example: |
Enters global configuration mode. |
| Step 3 |
{ipv6 access-list list-name Example: |
Defines an IPv6 ACL name, and enters IPv6 access list configuration mode. |
| Step 4 |
{deny | permit} protocol {source-ipv6-prefix/ |prefix-length |any| host source-ipv6-address} [ operator [ port-number ]] { destination-ipv6-prefix/ prefix-length | any | host destination-ipv6-address} [operator [port-number]][dscp value] [fragments] [log] [log-input] [routing] [sequence value] [time-range name] |
Enter deny or permit to specify whether to deny or permit the packet if conditions are matched. These are the conditions:
|
| Step 5 |
{deny | permit} tcp {source-ipv6-prefix/prefix-length | any | host source-ipv6-address} [operator [port-number]] {destination-ipv6- prefix/prefix-length | any | host destination-ipv6-address} [operator [port-number]] [ack] [dscp value] [established] [fin] [log] [log-input] [neq {port | protocol}] [psh] [range {port | protocol}] [rst] [routing] [sequence value] [syn] [time-range name] [urg] |
(Optional) Define a TCP access list and the access conditions. Enter tcp for Transmission Control Protocol. The parameters are the same as those described in Step 3a, with these additional optional parameters:
|
| Step 6 |
{deny | permit} udp {source-ipv6-prefix/prefix-length | any | host source-ipv6-address} [operator [port-number]] {destination-ipv6-prefix/prefix-length | any | host destination-ipv6-address} [operator [port-number]] [dscp value] [log] [log-input] [neq {port | protocol}] [range {port | protocol}] [routing] [sequence value] [time-range name]] |
(Optional) Define a UDP access list and the access conditions. Enter udp for the User Datagram Protocol. The UDP parameters are the same as those described for TCP, except that the [operator [port]] port number or name must be a UDP port number or name, and the established parameter is not valid for UDP. |
| Step 7 |
{deny | permit} icmp {source-ipv6-prefix/prefix-length | any | host source-ipv6-address} [operator [port-number]] {destination-ipv6-prefix/prefix-length | any | host destination-ipv6-address} [operator [port-number]] [icmp-type [icmp-code] | icmp-message] [dscp value] [log] [log-input] [routing] [sequence value] [time-range name] |
(Optional) Define an ICMP access list and the access conditions. Enter icmp for Internet Control Message Protocol. The ICMP parameters are the same as those described for most IP protocols in Step 1, with the addition of the ICMP message type and code parameters. These optional keywords have these meanings:
|
| Step 8 |
end |
Return to privileged EXEC mode. |
| Step 9 |
show ipv6 access-list |
Verify the access list configuration. |
| Step 10 |
show running-config Example: |
Verifies your entries. |
| Step 11 |
copy running-config startup-config Example: |
(Optional) Saves your entries in the configuration file. |
You can apply an ACL to outbound or inbound traffic on Layer 3 interfaces, or to inbound traffic on Layer 2 interfaces. You can also apply ACLs only to inbound management traffic on Layer 3 interfaces.
Follow these steps to control access to an interface:
| Command or Action | Purpose | |||
|---|---|---|---|---|
| Step 1 |
enable Example: |
Enables privileged EXEC mode.
|
||
| Step 2 |
configure terminal Example: |
Enters global configuration mode. |
||
| Step 3 |
interface interface-id |
Identify a Layer 2 interface (for port ACLs) or Layer 3 interface (for router ACLs) on which to apply an access list, and enter interface configuration mode. |
||
| Step 4 |
no switchport |
If applying a router ACL, this changes the interface from Layer 2 mode (the default) to Layer 3 mode. |
||
| Step 5 |
ipv6 address ipv6-address |
Configure an IPv6 address on a Layer 3 interface (for router ACLs). |
||
| Step 6 |
ipv6 traffic-filter access-list-name {in | out} |
Apply the access list to incoming or outgoing traffic on the interface.
|
||
| Step 7 |
end Example: |
Returns to privileged EXEC mode. |
||
| Step 8 |
show running-config Example: |
Verifies your entries. |
||
| Step 9 |
copy running-config startup-config Example: |
(Optional) Saves your entries in the configuration file. |
You can display information about all configured access lists, all IPv6 access lists, or a specific access list by using one or more of the privileged EXEC commands shown in the table below:
| Command | Purpose |
|---|---|
| show access-lists | Displays all access lists configured on the switch. |
| show ipv6 access-list [access-list-name] | Displays all configured IPv6 access lists or the access list specified by name. |
This is an example of the output from the show access-lists privileged EXEC command. The output shows all access lists that are configured on the switch or switch stack.
Switch # show access-lists
Extended IP access list hello
10 permit ip any any
IPv6 access list ipv6
permit ipv6 any any sequence 10This is an example of the output from the show ipv6 access-list privileged EXEC command. The output shows only IPv6 access lists configured on the switch or switch stack
Switch# show ipv6 access-list
IPv6 access list inbound
permit tcp any any eq bgp (8 matches) sequence 10
permit tcp any any eq telnet (15 matches) sequence 20
permit udp any any sequence 30
IPv6 access list outbound
deny udp any any sequence 10
deny tcp any any eq telnet sequence 20Before you configure the IPv6 PACL feature, you must configure an IPv6 access list. Once you have configured the IPv6 access list, you must configure the port-based access control list (PACL) mode on the specified IPv6 Layer 2 interface.
| Command or Action | Purpose | |
|---|---|---|
| Step 1 |
enable Example: |
Enables privileged EXEC mode.
|
| Step 2 |
configure terminal Example: |
Enters global configuration mode. |
| Step 3 |
ipv6 access-list access-list-name Example: |
Defines an IPv6 ACL and enters IPv6 access list configuration mode. |
| Step 4 |
exit Example: |
Exits IPv6 access list configuration mode and enters global configuration mode. |
| Step 5 |
interface type number Example: |
Specifies an interface type and number and enters interface configuration mode. |
| Step 6 |
ipv6 traffic-filter access-list-name {in | out } Example: |
Filters incoming and outgoing IPv6 traffic on an interface. |
| Step 7 |
end Example: |
Exits interface configuration mode and enters privileged EXEC mode. |
| Command or Action | Purpose | |
|---|---|---|
| Step 1 |
enable Example: |
Enables privileged EXEC mode.
|
| Step 2 |
configure terminal Example: |
Enters global configuration mode. |
| Step 3 |
ipv6 access-list access-list-name Example: |
Defines an IPv6 ACL and enters IPv6 access list configuration mode. |
| Step 4 |
permit protocol {source-ipv6-prefix / prefix-length | any | host source-ipv6-address | auth } [operator [port-number ]] {destination-ipv6-prefix / prefix-length | any | host destination-ipv6-address | auth } [operator [port-number ]] [dest-option-type [header-number | header-type ]] [dscp value ] [flow-label value ] [fragments ] [hbh ] [log ] [log-input ] [mobility ] [mobility-type [mh-number | mh-type ]] [reflect name [timeout value ]] [routing ] [routing-type routing-number ] [sequence value ] [time-range name ] Example: |
Sets permit conditions for the IPv6 ACL. |
| Step 5 |
deny protocol {source-ipv6-prefix / prefix-length | any | host source-ipv6-address | auth } [operator [port-number ]] {destination-ipv6-prefix/prefix-length | any | host destination-ipv6-address | auth } [operator [port-number ]] [dest-option-type [header-number | header-type ]] [dscp value ] [flow-label value ] [fragments ] [hbh ] [log ] [log-input ] [mobility ] [mobility-type [mh-number | mh-type ]] [routing ] [routing-type routing-number ] [sequence value ] [time-range name ] [undetermined-transport ] Example: |
Sets deny conditions for the IPv6 ACL. |
| Step 6 |
end Example: |
Returns to privileged EXEC configuration mode. |
Configuration Examples for IPv6 ACLs
This example configures the IPv6 access list named CISCO. The first deny entry in the list denies all packets that have a destination TCP port number greater than 5000. The second deny entry denies packets that have a source UDP port number less than 5000. The second deny also logs all matches to the console. The first permit entry in the list permits all ICMP packets. The second permit entry in the list permits all other traffic. The second permit entry is necessary because an implicit deny -all condition is at the end of each IPv6 access list.
Switch(config)# ipv6 access-list CISCO
Switch(config-ipv6-acl)# deny tcp any any gt 5000
Switch config-ipv6-acl)# deny ::/0 lt 5000 ::/0 log
Switch(config-ipv6-acl)# permit icmp any any
Switch(config-ipv6-acl)# permit any any
Switch(config-if)# no switchport
Switch(config-if)# ipv6 address 2001::/64 eui-64
Switch(config-if)# ipv6 traffic-filter CISCO outDevice# configure terminalDevice(config)# ipv6 access-list list1Device(config-ipv6-acl)# exitDevice(config-if)# ipv6 traffic-filter list1 in
Device(config)# ipv6 access-list hbh_acl
Device(config-ipv6-acl)# permit tcp any any hbh
Device(config-ipv6-acl)# permit tcp any any
Device(config-ipv6-acl)# permit udp any any
Device(config-ipv6-acl)# permit udp any any hbh
Device(config-ipv6-acl)# permit hbh any any
Device(config-ipv6-acl)# permit any any
Device(config-ipv6-acl)# hardware statistics
Device(config-ipv6-acl)# exit
! Assign an IP address and add the ACL on the interface.
Device(config)# interface FastEthernet3/1
Device(config-if)# ipv6 address 1001::1/64
Device(config-if)# ipv6 traffic-filter hbh_acl in
Device(config-if)# exit
Device(config)# exit
Device# clear counters
Clear "show interface" counters on all interfaces [confirm]
Device#
! Verify the configurations.
Device# show running-config interface FastEthernet3/1
Building configuration...
Current configuration : 114 bytes
!
interface FastEthernet3/1
no switchport
ipv6 address 1001::1/64
ipv6 traffic-filter hbh_acl
end
| MIB | MIBs Link |
|---|---|
|
All the supported MIBs for this release. |
To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL: |
| 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. |
The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.|
Feature Name |
Releases |
Feature Information |
|---|---|---|
|
IPv6 ACL Extensions for Hop-by-Hop Filtering |
15.1(1)SG |
Allows you to control IPv6 traffic that might contain hop-by-hop extension headers. This feature was supported on CAT3560C, CAT3560CX, CAT3560X, CAT3750X, CAT4500-X. The following commands were introduced or modified: deny (IPv6) , permit (IPv6) . |
|
IPv6 PACL Support |
The IPv6 PACL feature permits or denies the movement of traffic between port-based interface, Layer 3 subnets, wireless or wired clients, and VLANs, or within a VLAN. This feature was supported on CAT2960, CAT2960S, CAT3560X, CAT3650, CAT3560CX, CAT4500. The following command was introduced or modified: ipv6 traffic-filter . |
|
|
IPv6 Services: Extended Access Control Lists |
12.2(25)SG |
Standard IPv6 ACL functionality was extended to support traffic filtering based on IPv6 option headers and optional, upper-layer protocol type information for finer granularity of control. |
|
IPv6 Services: Standard Access Control Lists |
12.2(25)SG |
Access lists determine what traffic is blocked and what traffic is forwarded at router interfaces and allow filtering based on source and destination addresses, inbound and outbound to a specific interface. |
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