Cisco MDS 9000 Family NX-OS Security Configuration Guide
Configuring Cisco TrustSec Fibre Channel Link Encryption
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Configuring Cisco TrustSec Fibre Channel Link Encryption

Table Of Contents

Configuring Cisco TrustSec Fibre Channel Link Encryption

Cisco TrustSec FC Link Encryption Terminology

Support for AES Encryption

About Cisco TrustSec FC Link Encryption

Supported Modules

Enabling Cisco TrustSec FC Link Encryption

Setting Up Security Associations

Setting Up Security Association Parameters

Configuring ESP Settings

Configuring ESP on Ingress and Egress Ports

Configuring ESP Modes

Viewing Cisco TrustSec FC Link Encryption Information

Viewing FC-SP Interface Information

Viewing Running System Information

Viewing FC-SP Interface Statistics

Cisco TrustSec FC Link Encryption Best Practices

General Best Practices

Best Practices for Changing Keys


Configuring Cisco TrustSec Fibre Channel Link Encryption


This chapter provides an overview of the Cisco TrustSec Fibre Channel (FC) Link Encryption feature and describes how to configure and set up link-level encryption between switches.

The chapter includes the following sections:

Cisco TrustSec FC Link Encryption Terminology

Support for AES Encryption

About Cisco TrustSec FC Link Encryption

Viewing Cisco TrustSec FC Link Encryption Information

Cisco TrustSec FC Link Encryption Best Practices

Cisco TrustSec FC Link Encryption Terminology

The following Cisco TrustSec FC Link Encryption-related terms are used in this chapter:

Galois Counter Mode (GCM)—A block cipher mode of operation providing confidentiality and data-origin authentication.

Galois Message Authentication Code (GMAC)—A block cipher mode of operation providing only data-origin authentication. It is the authentication-only variant of GCM.

Security Association (SA)—A connection that handles the security credentials and controls how they propagate between switches. The SA includes parameters such as salt and keys.

Key—A 128-bit hexadecimal string that is used for frame encryption and decryption. The default value is zero.

Salt —A 32-bit hexadecimal number that is used during encryption and decryption. The same salt must be configured on both sides of the connection to ensure proper communication. The default value is zero.

Security Parameters Index (SPI) number—A 32-bit number that identifies the SA to be configured to the hardware. The range is from 256 to 4,294,967,295.

Support for AES Encryption

The Advanced Encryption Standard (AES) is the symmetric cipher algorithm that provides a high-level of security, and can accept different key sizes.

The Cisco TrustSec FC Link Encryption feature supports the 128-bit AES for security encryption and enables either AES-GCM or AES-GMAC for an interface. The AES-GCM mode provides encryption and authentication of the frames and AES-GMAC provides only the authentication of the frames that are being passed between the two peers.

About Cisco TrustSec FC Link Encryption

Cisco TrustSec FC Link Encryption is an extension of the Fibre Channel-Security Protocol (FC-SP) feature and uses the existing FC-SP architecture to provide integrity and confidentiality of transactions. Encryption is now added to the peer authentication capability to provide security and prevent unwanted traffic interception. Peer authentication is implemented according to the FC-SP standard using the Diffie-Hellman Challenge Handshake Authentication Protocol (DHCHAP) protocol.


Note Cisco TrustSec FC Link Encryption is currently only supported between Cisco MDS switches. This feature is not supported when you downgrade to software versions which do not have the Encapsulating Security Protocol (ESP) support.


This section includes the following topics:

Supported Modules

Enabling Cisco TrustSec FC Link Encryption

Setting Up Security Associations

Setting Up Security Association Parameters

Configuring ESP Settings

Supported Modules

The following modules are supported for the Cisco TrustSec FC Link Encryption feature:

1/2/4/8 Gbps 24-Port Fibre Channel switching module (DS-X9224-96K9)

1/2/4/8 Gbps 48-Port Fibre Channel switching module (DS-X9248-96K9)

1/2/4/8 Gbps 4/44-Port Fibre Channel switching module (DS-X9248-48K9)

Enabling Cisco TrustSec FC Link Encryption

By default, the FC-SP feature and the Cisco TrustSec FC Link Encryption feature are disabled in all switches in the Cisco MDS 9000 Family.

You must explicitly enable the FC-SP feature to access the configuration and verification commands for fabric authentication and encryption. When you disable this feature, all related configurations are automatically discarded.

To enable FC-SP for a Cisco MDS switch, follow these steps:

 
Command
Purpose

Step 1 

switch# config t

Enters configuration mode.

Step 2 

switch(config)# feature fcsp

Enables the FC-SP feature.

switch(config)# no feature fcsp

Disables (default) the FC-SP feature in this switch.

Configuring the Cisco TrustSec FC Link Encryption feature requires the ENTERPRISE_PKG license. For more information, refer to the Cisco MDS 9000 Family NX-OS Licensing Guide.

Setting Up Security Associations

To perform encryption between the switches, a security association (SA) needs to be set up. An administrator manually configures the SA before the encryption can take place. The SA includes parameters such as keys and salt, that are required for encryption. You can set up to 2000 SAs in a switch.

To set up an SA between two switches, follow these steps:

 
Command
Purpose

Step 1 

switch# config t

Enters configuration mode.

Step 2 

switch(config)# fcsp esp sa spi_number

Enters into SA submode for configuring SAs. The range of spi_number is from 256 to 4294967295.

Step 3 

switch(config)# no fcsp esp sa spi_number

Deletes the SA between the switches.1

1 If the specified SA is currently programmed to the ports, this command returns an error saying that the SA is in use.

To determine which ports are using the SA, use the show running-config fcsp command. Refer to the Viewing Running System Information.


Note Cisco TrustSec FC Link Encryption is currently supported only on DHCHAP on and off modes.


Setting Up Security Association Parameters

To set up the SA parameters, such as keys and salt, follow these steps:

 
Command
Purpose

Step 1 

switch# config t

Enters configuration mode.

Step 2 

Step 3 

Step 4 

switch(config)# fcsp esp sa spi_number

Enters into SA submode for configuring SAs. The range of spi_number is from 256 to 4294967295.

switch(config-sa)# key key

Configures the key for the SA. Maximum size of key is 34.

Step 5 

switch(config-sa)# no key key

Removes the key from the SA.

Step 6 

switch(config-sa)# salt salt

Configures the salt for the SA. The range is from 0x0 to 0xffffffff.

Step 7 

switch(config-sa)# no salt salt

Removes the salt for the SA.

Configuring ESP Settings

This section includes the following topics:

Configuring ESP on Ingress and Egress Ports

Configuring ESP Modes

Configuring ESP on Ingress and Egress Ports

Once the SA is created, you need to configure Encapsulating Security Protocol (ESP) on the ports. You should specify the egress and ingress ports for the encryption and decryption of packets between the network peers. The egress SA specifies which keys or parameters are to be used for encrypting the packets that leave the switch. The ingress SA specifies which keys or parameters are to be used to decrypt the packets entering that particular port.

This section covers the following topics:

Configuring ESP on Ingress Port

Configuring ESP on Egress Ports

Configuring ESP on Ingress Port

To configure SA to the ingress hardware, follow these steps:

Step 1 

Step 2 

Step 3 

switch# config t

Enters the configuration mode.

switch(config)# interface fc x/y

Configures the FC interface on slot x, port y.

switch(config-if)# fcsp esp manual

Enters the ESP configuration submode.

Step 4 

switch(config-if)# ingress-sa spi_number

Configures the SA to the ingress hardware.

Step 5 

switch(config-if)# no ingress-sa spi_number

Removes the SA from the ingress hardware.1

1 If SA is not configured in the ingress port, then running this command returns an error message.

Configuring ESP on Egress Ports

To configure SA to the egress hardware, follow these steps:

Step 1 

Step 2 

Step 3 

switch# config t

Enters the configuration mode.

switch(config)# interface fc x/y

Configures the FC interface on slot x, port y.

switch(config-if)# fcsp esp manual

Enters the ESP configuration submode.

Step 4 

switch(config-if)# egress-sa spi_number

Configures the SA to the egress hardware.

Step 5 

switch(config-if)# no egress-sa spi_number

Removes the SA from the egress hardware.1

1 If SA is not configured in the egress port, then running this command returns an error message.


Note To apply the SA to the ingress and egress hardware of an interface, the interface needs to be in the admin shut mode.


Configuring ESP Modes

Configure the ESP settings for the ports as GCM to enable message authentication and encryption or as GMAC to enable message authentication.

The default ESP mode is AES-GCM.

This section covers the following topics:

Configuring AES-GCM

Configuring AES-GMAC

Configuring AES-GCM

To configure the AES-GCM mode, follow these steps:

 
Command
Purpose

Step 1 

switch# config t

Enters the configuration mode.

Step 2 

Step 3 

Step 4 

switch(config)# interface fc x/y

Configures the FC interface on slot x, port y.

switch(config-if)# fcsp esp manual

Enters the ESP configuration submode to configure the ESP settings on each port.

Step 5 

switch(config-if-esp)# mode gcm

Sets the GCM mode for the interface.

Configuring AES-GMAC

To configure AES-GMAC mode, follow these steps:

 
Command
Purpose

Step 1 

switch# config t

Enters the configuration mode.

Step 2 

Step 3 

Step 4 

switch(config)# interface fc x/y

Configures the FC interface on slot x, port y.

switch(config-if)# fcsp esp manual

Enters the ESP configuration submode to configure the ESP settings on each port.

Step 5 

switch(config-if-esp)# mode gmac

Sets the GMAC mode for the interface.

Step 6 

switch(config-if-esp)# no mode gmac

Removes the GMAC mode from the interface and applies the default AES-GCM mode.


Note The ESP modes are set only after a SA is configured to either the ingress or the egress hardware. If SA has not been configured, ESP is turned off and encapsulation does not occur.



Note An ESP mode change always needs a port flap because the change is not seamless if it is done after you configure the port; although the configurations are not rejected.



Note Only ISLs with FC-SP port mode turned on and available on ESP capable switches or blades are displayed.



Note .You can modify an existing ESP configuration provided the selected ISLs are enabled.


Viewing Cisco TrustSec FC Link Encryption Information

You can view information about the Cisco TrustSec FC Link Encryption feature using the show commands .

This section covers the following topics:

Viewing FC-SP Interface Information

Viewing Running System Information

Viewing FC-SP Interface Statistics

Viewing FC-SP Interface Information

Use the show fcsp interface command to show all FC-SP-related information for a specific interface.

switch# show fcsp interface fc7/41

fc7/41:
        fcsp authentication mode:SEC_MODE_OFF
        ESP is enabled
        configured mode is: GCM
        programmed ingress SA: 300, 303
        programmed egress SA: 300
        Status:FC-SP protocol in progress

Viewing Running System Information

Use the show running-config fcsp command to show all the run-time information relevant to FC-SP. All details about ESP and configured interfaces are displayed. Use this command to determine which ports are using SA.

switch# show running-config fcsp
version 4.1(2)
feature fcsp
fcsp esp sa 300
  key 0x00000000000000000000000000123456
  salt 0x123456
fcsp esp sa 301
  key 0x00000000000000000000000000123456
  salt 0x1234567
fcsp esp sa 302
  key 0x00000000000000000000000000123456
  salt 0x123456
 
interface fc8/48
  fcsp off
  fcsp esp manual
    ingress-sa 300
    ingress-sa 301
    egress-sa 300

Viewing FC-SP Interface Statistics

Use the show fcsp interface statistics command to show all statistics related to DHCHAP and ESP for an interface. The ESP statistics shown depend on the ESP supported by the port ASIC.

switch# show fcsp interface fc3/31 statistics

fc7/41:
		fcsp authentication mode:SEC_MODE_ON
        ESP is enabled
        configured mode is: GMAC
        programmed ingress SA: 256, 257
        programmed egress SA: 256
        Status:Successfully authenticated
		Authenticated using local password database
        Statistics:
        FC-SP Authentication Succeeded:17
        FC-SP Authentication Failed:3
        FC-SP Authentication Bypassed:0
        FC-SP ESP SPI Mismatched frames:0
        FC-SP ESP Auth failed frames:0

Cisco TrustSec FC Link Encryption Best Practices

Best practices are the recommended steps that should be taken to ensure the proper operation of Cisco TrustSec FC Link Encryption.

This section covers the following topics:

General Best Practices

Best Practices for Changing Keys

General Best Practices

This section lists the general best practices for Cisco TrustSec FC Link Encryption:

Ensure that Cisco TrustSec FC Link Encryption is enabled only between MDS switches. This feature is supported only on E-ports or the ISLs, and errors will result if non-MDS switches are used.

Ensure that the peers in the connection have the same configurations. If there are differences in the configurations, a "port re-init limit exceeded" error message is displayed.

Before applying the SA to the ingress and egress hardware of a switch interface, ensure that the interface is in the admin shut mode.

Best Practices for Changing Keys

After the SA is applied to the ingress and egress ports, you should change the keys periodically in the configuration. The keys should be changed sequentially to avoid traffic disruption.

As an example, consider that a security association has been created between two switches, Switch1 and Switch2. The SA is configured on the ingress and egress ports as shown in the following example:

switch# config t
switch(config)# interface fc1/1
switch(config-if)# fcsp esp manual
switch(config-if)# ingress-sa 256
switch(config-if)# egress-sa 256

To change the keys for these switches, follow these steps:


Step 1 Add a new SA on Switch1 and Switch2.

switch# config t
switch(config)# fcsp esp sa 257
switch(config-sa)# key 0xAC9EF8BC8DB2DBD2008D184F794E0C38
switch(config-sa)# salt 0x1234

Step 2 Configure the ingress SA on Switch1.

switch# config t
switch(config)# interface fc1/1
switch(config-if)# fcsp esp manual
switch(config-if)# ingress-sa 257

Step 3 Configure the ingress and the egress SA on Switch2.

switch# config t
switch(config)# interface fc1/1
switch(config-if)# fcsp esp manual
switch(config-if)# ingress-sa 257
switch(config-if)# egress-sa 257

Step 4 Configure the egress SA on Switch1.

switch# config t
switch(config)# interface fc1/1
switch(config-if)# fcsp esp manual
switch(config-if)# egress-sa 257

Step 5 Remove the previously configured ingress SA from both the switches.

switch# config t
switch(config)# interface fc1/1
switch(config-if)# fcsp esp manual
switch(config-if)# no ingress-sa 256