Catalyst 6500 Release 12.2SXF and Rebuilds Software Configuration Guide

Configuring Port Security

This chapter describes how to configure the port security feature.

Note For complete syntax and usage information for the commands used in this chapter, refer to the Cisco IOS Master Command List, Release 12.2SX at this URL:

http://www.cisco.com/en/US/docs/ios/mcl/allreleasemcl/all_book.html

This chapter consists of these sections:

•Understanding Port Security

•Default Port Security Configuration

•Port Security Guidelines and Restrictions

•Configuring Port Security

•Displaying Port Security Settings

Tip For additional information about Cisco Catalyst 6500 Series Switches (including configuration examples and troubleshooting information), see the documents listed on this page:

http://www.cisco.com/en/US/products/hw/switches/ps708/tsd_products_support_series_home.html

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Understanding Port Security

These sections describe port security:

•Port Security with Dynamically Learned and Static MAC Addresses

•Port Security with Sticky MAC Addresses

Port Security with Dynamically Learned and Static MAC Addresses

You can use port security with dynamically learned and static MAC addresses to restrict a port's ingress traffic by limiting the MAC addresses that are allowed to send traffic into the port. When you assign secure MAC addresses to a secure port, the port does not forward ingress traffic that has source addresses outside the group of defined addresses. If you limit the number of secure MAC addresses to one and assign a single secure MAC address, the device attached to that port has the full bandwidth of the port.

A security violation occurs in either of these situations:

•When the maximum number of secure MAC addresses is reached on a secure port and the source MAC address of the ingress traffic is different from any of the identified secure MAC addresses, port security applies the configured violation mode.

•If traffic with a secure MAC address that is configured or learned on one secure port attempts to access another secure port in the same VLAN, port security responds to the violation in one of these ways:

–In Release 12.2(18)SXF5 and later releases, port security applies the configured violation mode.

–In releases earlier than Release 12.2(18)SXF5, port security applies the shutdown violation mode.

Note After a secure MAC address is configured or learned on one secure port, the sequence of events that occurs when port security detects that secure MAC address on a different port in the same VLAN is known as a MAC move violation.

See the "Configuring the Port Security Violation Mode on a Port" section for more information about the violation modes.

After you have set the maximum number of secure MAC addresses on a port, port security includes the secure addresses in the address table in one of these ways:

•You can statically configure all secure MAC addresses by using the switchport port-security mac-address mac_address interface configuration command.

•You can allow the port to dynamically configure secure MAC addresses with the MAC addresses of connected devices.

•You can statically configure a number of addresses and allow the rest to be dynamically configured.

If the port has a link-down condition, all dynamically learned addresses are removed.

Following bootup, a reload, or a link-down condition, port security does not populate the address table with dynamically learned MAC addresses until the port receives ingress traffic.

A security violation occurs if the maximum number of secure MAC addresses have been added to the address table and the port receives traffic from a MAC address that is not in the address table.

You can configure the port for one of three violation modes: protect, restrict, or shutdown. See the "Configuring Port Security" section.

To ensure that an attached device has the full bandwidth of the port, set the maximum number of addresses to one and configure the MAC address of the attached device.

Port Security with Sticky MAC Addresses

Release 12.2(18)SXE and later releases support port security with sticky MAC addresses. Port security with sticky MAC addresses provides many of the same benefits as port security with static MAC addresses, but sticky MAC addresses can be learned dynamically. Port security with sticky MAC addresses retains dynamically learned MAC addresses during a link-down condition.

If you enter a write memory or copy running-config startup-config command, then port security with sticky MAC addresses saves dynamically learned MAC addresses in the startup-config file and the port does not have to learn addresses from ingress traffic after bootup or a restart.

Default Port Security Configuration

Table 47-1 shows the default port security configuration for an interface.

Port Security Guidelines and Restrictions

When configuring port security, follow these guidelines:

•With the default port security configuration, to bring all secure ports out of the error-disabled state, enter the errdisable recovery cause psecure-violation global configuration command, or manually reenable it by entering the shutdown and no shut down interface configuration commands.

•Enter the clear port-security dynamic global configuration command to clear all dynamically learned secure addresses. See the Cisco IOS Master Command List, Release 12.2SX, for complete syntax information.

•Port security learns unauthorized MAC addresses with a bit set that causes traffic to them or from them to be dropped. The show mac-address-table command displays the unauthorized MAC addresses, but does not display the state of the bit. (CSCeb76844)

•To preserve dynamically learned sticky MAC addresses and configure them on a port following a bootup or a reload and after the dynamically learned sticky MAC addresses have been learned, you must enter a write memory or copy running-config startup-config command to save them in the startup-config file.

•With Release 12.2(18)SXE and later releases, port security supports private VLAN (PVLAN) ports.

•With releases earlier than Release 12.2(18)SXE, port security does not support PVLAN ports.

•With Release 12.2(18)SXE and later releases, port security supports nonnegotiating trunks.

–Port security only supports trunks configured with these commands:

switchport
switchport trunk encapsulation
switchport mode trunk
switchport nonegotiate

–If you reconfigure a secure access port as a trunk, port security converts all the sticky and static secure addresses on that port that were dynamically learned in the access VLAN to sticky or static secure addresses on the native VLAN of the trunk. Port security removes all secure addresses on the voice VLAN of the access port.

–If you reconfigure a secure trunk as an access port, port security converts all sticky and static addresses learned on the native VLAN to addresses learned on the access VLAN of the access port. Port security removes all addresses learned on VLANs other than the native VLAN.

Note Port security uses the VLAN ID configured with the switchport trunk native vlan command for both IEEE 802.1Q trunks and ISL trunks.

•With releases earlier than Release 12.2(18)SXE, port security does not support trunks.

•With Release 12.2(18)SXE and later releases, port security supports IEEE 802.1Q tunnel ports.

•With releases earlier than Release 12.2(18)SXE, port security does not support IEEE 802.1Q tunnel ports.

•Port security does not support Switch Port Analyzer (SPAN) destination ports.

•Port security does not support EtherChannel port-channel interfaces.

•With releases earlier than Release 12.2(33)SXH, port security and 802.1X port-based authentication cannot both be configured on the same port:

–If you try to enable 802.1X port-based authentication on a secure port, an error message appears and 802.1X port-based authentication is not enabled on the port.

–If you try to enable port security on a port configured for 802.1X port-based authentication, an error message appears and port security is not enabled on the port.

•Take care when you enable port security on the ports connected to the adjacent switches when there are redundant links running between the switches because port security might error-disable the ports due to port security violations.

Configuring Port Security

These sections describe how to configure port security:

•Enabling Port Security

•Configuring the Port Security Violation Mode on a Port

•Configuring the Port Security Rate Limiter

•Configuring the Maximum Number of Secure MAC Addresses on a Port

•Enabling Port Security with Sticky MAC Addresses on a Port

•Configuring a Static Secure MAC Address on a Port

•Configuring Secure MAC Address Aging on a Port

Enabling Port Security

These sections describe how to enable port security:

•Enabling Port Security on a Trunk

•Enabling Port Security on an Access Port

Enabling Port Security on a Trunk

With Release 12.2(18)SXE and later releases, port security supports nonnegotiating trunks.

Caution Because the default number of secure addresses is one and the default violation action is to shut down the port, configure the maximum number of secure MAC addresses on the port before you enable port security on a trunk (see "Configuring the Maximum Number of Secure MAC Addresses on a Port" section).

To enable port security on a trunk, perform this task:

This example shows how to configure Fast Ethernet port 5/36 as a nonnegotiating trunk and enable port security:

Router# configure terminal 

Enter configuration commands, one per line.  End with CNTL/Z.

Router(config)# interface fastethernet 5/36 

Router(config-if)# switchport 

Router(config-if)# switchport mode trunk 

Router(config-if)# switchport nonegotiate 

Router(config-if)# switchport port-security 

Router(config-if)# do show port-security interface fastethernet 5/36 | include Port Security 

Port Security              : Enabled

Enabling Port Security on an Access Port

To enable port security on an access port, perform this task:

This example shows how to enable port security on Fast Ethernet port 5/12:

Router# configure terminal

Enter configuration commands, one per line.  End with CNTL/Z.

Router(config)# interface fastethernet 5/12

Router(config-if)# switchport 

Router(config-if)# switchport mode access

Router(config-if)# switchport port-security

Router(config-if)# do show port-security interface fastethernet 5/12 | include Port Security

Port Security              : Enabled

Configuring the Port Security Violation Mode on a Port

To configure the port security violation mode on a port, perform this task:

When configuring port security violation modes, note the following information:

•protect—Drops packets with unknown source addresses until you remove a sufficient number of secure MAC addresses to drop below the maximum value.

•restrict—Drops packets with unknown source addresses until you remove a sufficient number of secure MAC addresses to drop below the maximum value and causes the SecurityViolation counter to increment.

•shutdown—Puts the interface into the error-disabled state immediately and sends an SNMP trap notification.

Note•To bring a secure port out of the error-disabled state, enter the errdisable recovery cause violation_mode global configuration command, or you can manually reenable it by entering the shutdown and no shut down interface configuration commands.

•To protect the CPU against overutilization, when you configure the protect or restrict violation modes, configure the packet drop rate limiter (see the "Configuring the Port Security Rate Limiter" section).

This example shows how to configure the protect security violation mode on Fast Ethernet port 5/12:

Router# configure terminal

Enter configuration commands, one per line.  End with CNTL/Z.

Router(config)# interface fastethernet 3/12

Router(config-if)# switchport port-security violation protect 

Router(config-if)# do show port-security interface fastethernet 5/12 | include Protect

Violation Mode             : Protect

This example shows how to configure the restrict security violation mode on Fast Ethernet port 5/12:

Router# configure terminal

Enter configuration commands, one per line.  End with CNTL/Z.

Router(config)# interface fastethernet 3/12

Router(config-if)# switchport port-security violation restrict 

Router(config-if)# do show port-security interface fastethernet 5/12 | include Restrict

Violation Mode             : Restrict

Configuring the Port Security Rate Limiter

Note•The PFC2 does not support the port security rate limiter.

•The truncated switching mode does not support the port security rate limiter.

Port security examines all traffic received by secure ports to detect violations or to recognize and secure new MAC addresses. When the shutdown violation mode is configured, traffic cannot enter the secure port after a violation has been detected, which removes the possibility that violations might cause excessive CPU load.

When the protect or restrict violation modes are configured, port security continues to process traffic after a violation occurs, which might cause excessive CPU load. Configure the port security rate limiter to protect the CPU against excessive load when the protect or restrict violation modes are configured.

To configure the port security rate limiter, perform this task:

When configuring the port security rate limiter, note the following information:

•For the rate_in_pps value:

–The range is 10 through 1,000,000 (entered as 1000000).

–There is no default value.

–The lower the value, the more the CPU is protected. The rate limiter is applied to traffic both before and after a security violation occurs. Configure a value high enough to permit nonviolating traffic to reach the port security feature.

–Values lower than 1,000 (entered as 1000) should offer sufficient protection.

•For the burst_size value:

–The range is 1 through 255.

–The default is 10.

–The default value should provide sufficient protection.

This example shows how to configure the port security rate limiter:

Router# configure terminal

Enter configuration commands, one per line.  End with CNTL/Z.

Router(config)# mls rate-limit layer2 port-security 1000 

Router(config)# end 

This example shows how to verify the configuration:

Router# show mls rate-limit | include PORTSEC 

LAYER_2 PORTSEC   On               1000       1  Not sharing

Configuring the Maximum Number of Secure MAC Addresses on a Port

To configure the maximum number of secure MAC addresses on a port, perform this task:

When configuring the maximum number of secure MAC addresses on a port, note the following information:

•With Release 12.2(18)SXE and later releases, the range for number_of_addresses is 1 to 4,097.

•With releases earlier than Release 12.2(18)SXE, the range for number_of_addresses is 1 to 1,024.

•With Release 12.2(18)SXE and later releases, port security supports trunks.

–On a trunk, you can configure the maximum number of secure MAC addresses both on the trunk and for all the VLANs on the trunk.

–You can configure the maximum number of secure MAC addresses on a single VLAN or a range of VLANs.

–For a range of VLANs, enter a dash-separated pair of VLAN numbers.

–You can enter a comma-separated list of VLAN numbers and dash-separated pairs of VLAN numbers.

This example shows how to configure a maximum of 64 secure MAC addresses on Fast Ethernet port 5/12:

Router# configure terminal

Enter configuration commands, one per line.  End with CNTL/Z.

Router(config)# interface fastethernet 3/12

Router(config-if)# switchport port-security maximum 64 

Router(config-if)# do show port-security interface fastethernet 5/12 | include Maximum

Maximum MAC Addresses      : 64

Enabling Port Security with Sticky MAC Addresses on a Port

Release 12.2(18)SXE and later releases support port security with sticky MAC addresses. To enable port security with sticky MAC addresses on a port, perform this task:

When enabling port security with sticky MAC addresses, note the following information:

•When you enter the switchport port-security mac-address sticky command:

–All dynamically learned secure MAC addresses on the port are converted to sticky secure MAC addresses.

–Static secure MAC addresses are not converted to sticky MAC addresses.

–Secure MAC addresses dynamically learned in a voice VLAN are not converted to sticky MAC addresses.

–New dynamically learned secure MAC addresses are sticky.

•When you enter the no switchport port-security mac-address sticky command, all sticky secure MAC addresses on the port are converted to dynamic secure MAC addresses.

•To preserve dynamically learned sticky MAC addresses and configure them on a port following a bootup or a reload, after the dynamically learned sticky MAC addresses have been learned, you must enter a write memory or copy running-config startup-config command to save them in the startup-config file.

This example shows how to enable port security with sticky MAC addresses on Fast Ethernet port 5/12:

Router# configure terminal 

Enter configuration commands, one per line.  End with CNTL/Z.

Router(config)# interface fastethernet 5/12 

Router(config-if)# switchport port-security mac-address sticky 

Configuring a Static Secure MAC Address on a Port

To configure a static secure MAC address on a port, perform this task:

When configuring a static secure MAC address on a port, note the following information:

•With Release 12.2(18)SXE and later releases, you can configure sticky secure MAC addresses if port security with sticky MAC addresses is enabled (see the "Enabling Port Security with Sticky MAC Addresses on a Port" section).

•The maximum number of secure MAC addresses on the port, configured with the switchport port-security maximum command, defines how many secure MAC addresses you can configure.

•If you configure fewer secure MAC addresses than the maximum, the remaining MAC addresses are learned dynamically.

•With Release 12.2(18)SXE and later releases, port security is supported on trunks.

–On a trunk, you can configure a static secure MAC address in a VLAN.

–On a trunk, if you do not configure a VLAN for a static secure MAC address, it is secure in the VLAN configured with the switchport trunk native vlan command.

This example shows how to configure a MAC address 1000.2000.3000 as secure on Fast Ethernet port 5/12 and verify the configuration:

Router# configure terminal

Enter configuration commands, one per line.  End with CNTL/Z.

Router(config)# interface fastethernet 5/12

Router(config-if)# switchport port-security mac-address 1000.2000.3000

Router(config-if)# end 

Router# show port-security address

          Secure Mac Address Table

------------------------------------------------------------

Vlan    Mac Address       Type                Ports

----    -----------       ----                -----

   1    1000.2000.3000    SecureConfigured     Fa5/12

Configuring Secure MAC Address Aging on a Port

When the aging type is configured with the absolute keyword, all the dynamically learned secure addresses age out when the aging time expires. When the aging type is configured with the inactivity keyword, the aging time defines the period of inactivity after which all the dynamically learned secure addresses age out.

Note Static secure MAC addresses and sticky secure MAC addresses do not age out.

These sections describe how to configure secure MAC address aging on a port:

•Configuring the Secure MAC Address Aging Type on a Port

•Configuring Secure MAC Address Aging Time on a Port

Configuring the Secure MAC Address Aging Type on a Port

With a PFC3 and Release 12.2(18)SXE and later releases, you can configure the secure MAC address aging type on a port. With a PFC2, you cannot configure the secure MAC address aging type. The PFC2 supports only absolute aging.

To configure the secure MAC address aging type on a port, perform this task:

This example shows how to set the aging type to inactivity on Fast Ethernet Port 5/12:

Router# configure terminal

Enter configuration commands, one per line.  End with CNTL/Z.

Router(config)# interface fastethernet 5/12 

Router(config-if)# switchport port-security aging type inactivity 

Router(config-if)# do show port-security interface fastethernet 5/12 | include Type

Aging Type                 : Inactivity

Configuring Secure MAC Address Aging Time on a Port

To configure the secure MAC address aging time on a port, perform this task:

This example shows how to configure 2 hours (120 minutes) as the secure MAC address aging time on Fast Ethernet Port 5/1:

Router# configure terminal

Enter configuration commands, one per line.  End with CNTL/Z.

Router(config)# interface fastethernet 5/1 

Router(config-if)# switchport port-security aging time 120 

Router(config-if)# do show port-security interface fastethernet 5/12 | include Time

Aging Time                 : 120 mins

Displaying Port Security Settings

To display port security settings, enter this command:

When displaying port security settings, note the following information:

•Port security supports the vlan keyword only on trunks.

•Enter the address keyword to display secure MAC addresses, with aging information for each address, globally for the switch or per interface.

•The display includes these values:

–The maximum allowed number of secure MAC addresses for each interface

–The number of secure MAC addresses on the interface

–The number of security violations that have occurred

–The violation mode.

This example displays output from the show port-security command when you do not enter an interface:

Router# show port-security

Secure Port      MaxSecureAddr  CurrentAddr  SecurityViolation  Security

Action

                    (Count)        (Count)      (Count)

----------------------------------------------------------------------------

     Fa5/1           11            11            0            Shutdown

     Fa5/5           15            5             0            Restrict

     Fa5/11          5             4             0            Protect

----------------------------------------------------------------------------

Total Addresses in System: 21

Max Addresses limit in System: 128

This example displays output from the show port-security command for a specified interface:

Router# show port-security interface fastethernet 5/1

Port Security: Enabled

Port status: SecureUp

Violation mode: Shutdown

Maximum MAC Addresses: 11

Total MAC Addresses: 11

Configured MAC Addresses: 3

Aging time: 20 mins

Aging type: Inactivity

SecureStatic address aging: Enabled

Security Violation count: 0

This example displays the output from the show port-security address privileged EXEC command:

Router# show port-security address

          Secure Mac Address Table

-------------------------------------------------------------------

Vlan    Mac Address       Type                Ports   Remaining Age

                                                         (mins)

----    -----------       ----                -----   -------------

   1    0001.0001.0001    SecureDynamic       Fa5/1      15 (I)

   1    0001.0001.0002    SecureDynamic       Fa5/1      15 (I)

   1    0001.0001.1111    SecureConfigured    Fa5/1      16 (I)

   1    0001.0001.1112    SecureConfigured    Fa5/1      -

   1    0001.0001.1113    SecureConfigured    Fa5/1      -

   1    0005.0005.0001    SecureConfigured    Fa5/5      23

   1    0005.0005.0002    SecureConfigured    Fa5/5      23

   1    0005.0005.0003    SecureConfigured    Fa5/5      23

   1    0011.0011.0001    SecureConfigured    Fa5/11     25 (I)

   1    0011.0011.0002    SecureConfigured    Fa5/11     25 (I)

-------------------------------------------------------------------

Total Addresses in System: 10

Max Addresses limit in System: 128

Tip For additional information about Cisco Catalyst 6500 Series Switches (including configuration examples and troubleshooting information), see the documents listed on this page:

http://www.cisco.com/en/US/products/hw/switches/ps708/tsd_products_support_series_home.html

Participate in the Technical Documentation Ideas forum