Configuring PKI

This chapter describes the Public Key Infrastructure (PKI) support on the Cisco NX-OS device. PKI allows the device to obtain and use digital certificates for secure communication in the network and provides manageability and scalability for Secure Shell (SSH).

This chapter includes the following sections:

Information About PKI

This section provides information about PKI.

CAs and Digital Certificates

Certificate authorities (CAs) manage certificate requests and issue certificates to participating entities such as hosts, network devices, or users. The CAs provide centralized key management for the participating entities.

Digital signatures, based on public key cryptography, digitally authenticate devices and individual users. In public key cryptography, such as the RSA encryption system, each device or user has a key pair that contains both a private key and a public key. The private key is kept secret and is known only to the owning device or user only. However, the public key is known to everybody. Anything encrypted with one of the keys can be decrypted with the other. A signature is formed when data is encrypted with a sender’s private key. The receiver verifies the signature by decrypting the message with the sender’s public key. This process relies on the receiver having a copy of the sender’s public key and knowing with a high degree of certainty that it really does belong to the sender and not to someone pretending to be the sender.

Digital certificates link the digital signature to the sender. A digital certificate contains information to identify a user or device, such as the name, serial number, company, department, or IP address. It also contains a copy of the entity’s public key. The CA that signs the certificate is a third party that the receiver explicitly trusts to validate identities and to create digital certificates.

To validate the signature of the CA, the receiver must first know the CA’s public key. Typically, this process is handled out of band or through an operation done at installation. For instance, most web browsers are configured with the public keys of several CAs by default.

Trust Model, Trust Points, and Identity CAs

The PKI trust model is hierarchical with multiple configurable trusted CAs. You can configure each participating device with a list of trusted CAs so that a peer certificate obtained during the security protocol exchanges can be authenticated if it was issued by one of the locally trusted CAs. The Cisco NX-OS software locally stores the self-signed root certificate of the trusted CA (or certificate chain for a subordinate CA). The process of securely obtaining a trusted CA’s root certificate (or the entire chain in the case of a subordinate CA) and storing it locally is called CA authentication.

The information about a trusted CA that you have configured is called the trust point and the CA itself is called a trust point CA. This information consists of a CA certificate (or certificate chain in case of a subordinate CA) and certificate revocation checking information.

The Cisco NX-OS device can also enroll with a trust point to obtain an identity certificate to associate with a key pair. This trust point is called an identity CA.

CA Certificate Hierarchy

For secure services, you typically have multiple trusted CAs. The CAs are usually installed in all the hosts as a bundle. The NX-OS PKI infrastructure does support importing certificate chain. However, with the current CLIs, one chain at a time can be installed. This procedure can be cumbersome when there are several CA chains to be installed. This requires a facility to download CA bundles that could include several intermediate and root CAs.

Importing CA Bundle

The crypto CA trustpoint command binds the CA certificates, CRLs, identity certificates and key pairs to a named label. All files corresponding to each of these entities are stored in the NX-OS certstore directory (/isan/etc/certstore) and tagged with the trustpoint label.

To access the CA certificates, an SSL app only needs to point to the standard NX-OS cert-store and specify that as the CA path during SSL initialization. It does not need to be aware of the trustpoint label under which CAs are installed.

If clients need to bind to an identity certificate, the trustpoint label needs to be used as the binding point.

The import pkcs command is enhanced to install the CA certificates under a trustpoint label. This can be further enhanced to install a CA bundle. The import command structure is modified to add pkcs7 option which is used for providing CA bundle file in pkcs7 format.

Beginning with Cisco NX-OS Release 10.1(1), the pkcs7 file format is supported to unpack the CA bundle and install each CA chain under its own label. The labels are formed by appending an index to the main trustpoint label.

Once installed, there is no logical binding of all CA chains to a bundle.

Import of the CA Certificate Bundle in PKCS7 Format

To support the import of the ca certificate bundle which consists of multiple independent certificate chains, the option of ‘pkcs7’ is introduced in the crypto import command.

Procedure
  Command or Action Purpose

Step 1

configure terminal

Example:
switch# configure terminal
switch(config)#

Enters global configuration mode.

Step 2

crypto ca import <baselabel> pksc7 <uri0> force

There are two input arguments in the command. The source file which is the ca bundle file is given in the <uri0>, the input file has to be in pkcs7 format indicating that it is a cabundle file.

Multiple certificate chains will be extracted out of the cabundle. The command will generate multiple trustpoints with ca certificate chain attached to each one. Import command generates two configurations which are global CA bundle configuration and CA bundle sub-configuration with each trustpoint generated.

The force option removes the CA bundle and related trustpoint configurations, imports a new CA bundle with the same bundle name, and generates fresh trustpoint configurations related to the cabundle.

Step 3

crypto ca cabundle <bundle-name>

The bundle-name is same as baselabel for import case. You can use the no form of this command to delete the, CA bundle, trustpoints, and related certificate chains.

After importing CA bundle under a particular baselabel name and generating all the trustpoints, if a user try to execute the import command again under the same baselabel name, it will throw error saying CA bundle already exists. The user can use force option to modify the existing CA bundle.

Maximum number of Cabundles supported is 20.

Step 4

exit

Example:
switch(config)# exit
switch#

Exits configuration mode.

Step 5

(Optional) show crypto ca certificates

Example:
switch# show crypto ca certificates
 (Optional)

Displays the CA certificates.

Step 6

(Optional) copy running-config startup-config

Example:
switch# copy running-config startup-config
 (Optional)

Copies the running configuration to the startup configuration.

RSA Key Pairs and Identity Certificates

You can obtain an identity certificate by generating one or more RSA key pairs and associating each RSA key pair with a trust point CA where the Cisco NX-OS device intends to enroll. The Cisco NX-OS device needs only one identity per CA, which consists of one key pair and one identity certificate per CA.

The Cisco NX-OS software allows you to generate RSA key pairs with a configurable key size (or modulus). The default key size is 512. You can also configure an RSA key-pair label. The default key label is the device fully qualified domain name (FQDN).

The following list summarizes the relationship between trust points, RSA key pairs, and identity certificates:

  • A trust point corresponds to a specific CA that the Cisco NX-OS device trusts for peer certificate verification for any application (such as SSH).

  • A Cisco NX-OS device can have many trust points and all applications on the device can trust a peer certificate issued by any of the trust point CAs.

  • A trust point is not restricted to a specific application.

  • A Cisco NX-OS device enrolls with the CA that corresponds to the trust point to obtain an identity certificate. You can enroll your device with multiple trust points which means that you can obtain a separate identity certificate from each trust point. The identity certificates are used by applications depending upon the purposes specified in the certificate by the issuing CA. The purpose of a certificate is stored in the certificate as a certificate extension.

  • When enrolling with a trust point, you must specify an RSA key pair to be certified. This key pair must be generated and associated to the trust point before generating the enrollment request. The association between the trust point, key pair, and identity certificate is valid until it is explicitly removed by deleting the certificate, key pair, or trust point.

  • The subject name in the identity certificate is the fully qualified domain name for the Cisco NX-OS device.

  • You can generate one or more RSA key pairs on a device and each can be associated to one or more trust points. But no more than one key pair can be associated to a trust point, which means only one identity certificate is allowed from a CA.

  • If the Cisco NX-OS device obtains multiple identity certificates (each from a distinct CA), the certificate that an application selects to use in a security protocol exchange with a peer is application specific.

  • You do not need to designate one or more trust points for an application. Any application can use any certificate issued by any trust point as long as the certificate purpose satisfies the application requirements.

  • You do not need more than one identity certificate from a trust point or more than one key pair to be associated to a trust point. A CA certifies a given identity (or name) only once and does not issue multiple certificates with the same name. If you need more than one identity certificate for a CA and if the CA allows multiple certificates with the same names, you must define another trust point for the same CA, associate another key pair to it, and have it certified.

Multiple Trusted CA Support

The Cisco NX-OS device can trust multiple CAs by configuring multiple trust points and associating each with a distinct CA. With multiple trusted CAs, you do not have to enroll a device with the specific CA that issued the certificate to a peer. Instead, you can configure the device with multiple trusted CAs that the peer trusts. The Cisco NX-OS device can then use a configured trusted CA to verify certificates received from a peer that were not issued by the same CA defined in the identity of the peer device.

PKI Enrollment Support

Enrollment is the process of obtaining an identity certificate for the device that is used for applications like SSH. It occurs between the device that requests the certificate and the certificate authority.

The Cisco NX-OS device performs the following steps when performing the PKI enrollment process:

  • Generates an RSA private and public key pair on the device.

  • Generates a certificate request in standard format and forwards it to the CA.


Note

The CA administrator may be required to manually approve the enrollment request at the CA server, when the request is received by the CA.

  • Receives the issued certificate back from the CA, signed with the CA’s private key.

  • Writes the certificate into a nonvolatile storage area on the device (bootflash).

Manual Enrollment Using Cut-and-Paste

The Cisco NX-OS software supports certificate retrieval and enrollment using manual cut-and-paste. Cut-and-paste enrollment means that you must cut and paste the certificate requests and resulting certificates between the device and the CA.

You must perform the following steps when using cut and paste in the manual enrollment process:

  • Create an enrollment certificate request, which the Cisco NX-OS device displays in base64-encoded text form.

  • Cut and paste the encoded certificate request text in an e-mail or in a web form and send it to the CA.

  • Receive the issued certificate (in base64-encoded text form) from the CA in an e-mail or in a web browser download.

  • Cut and paste the issued certificate to the device using the certificate import facility.

Multiple RSA Key Pair and Identity CA Support

Multiple identity CAs enable the device to enroll with more than one trust point, which results in multiple identity certificates, each from a distinct CA. With this feature, the Cisco NX-OS device can participate in SSH and other applications with many peers using certificates issued by CAs that are acceptable to those peers.

The multiple RSA key-pair feature allows the device to maintain a distinct key pair for each CA with which it is enrolled. It can match policy requirements for each CA without conflicting with the requirements specified by the other CAs, such as the key length. The device can generate multiple RSA key pairs and associate each key pair with a distinct trust point. Thereafter, when enrolling with a trust point, the associated key pair is used to construct the certificate request.

Peer Certificate Verification

The PKI support on a Cisco NX-OS device can verify peer certificates. The Cisco NX-OS software verifies certificates received from peers during security exchanges for applications, such as SSH. The applications verify the validity of the peer certificates. The Cisco NX-OS software performs the following steps when verifying peer certificates:

  • Verifies that the peer certificate is issued by one of the locally trusted CAs.

  • Verifies that the peer certificate is valid (not expired) with respect to current time.

  • Verifies that the peer certificate is not yet revoked by the issuing CA.

For revocation checking, the Cisco NX-OS software supports the certificate revocation list (CRL). A trust point CA can use this method to verify that the peer certificate has not been revoked.

Certificate Revocation Checking

The Cisco NX-OS software can check the revocation status of CA certificates. The applications can use the revocation checking mechanisms in the order that you specify. The choices are CRL, NDcPP: OCSP for Syslog, none, or a combination of these methods.

CRL Support

The CAs maintain certificate revocation lists (CRLs) to provide information about certificates revoked prior to their expiration dates. The CAs publish the CRLs in a repository and provide the download public URL in all issued certificates. A client verifying a peer’s certificate can obtain the latest CRL from the issuing CA and use it to determine if the certificate has been revoked. A client can cache the CRLs of some or all of its trusted CAs locally and use them later if necessary until the CRLs expire.

The Cisco NX-OS software allows the manual configuration of predownloaded CRLs for the trust points, and then caches them in the device bootflash (cert-store). During the verification of a peer certificate, the Cisco NX-OS software checks the CRL from the issuing CA only if the CRL has already been cached locally and the revocation checking is configured to use the CRL. Otherwise, the Cisco NX-OS software does not perform CRL checking and considers the certificate to be not revoked unless you have configured other revocation checking methods.

NDcPP: OCSP for Syslog

Online Certificate Status Protocol (OCSP) is a method to check certificate revocation when a peer has to retrieve this revocation information and then validate it to check the certificate revocation status. In this method, the certification revocation status is limited by the peer's ability to reach an OCSP responder through the cloud or by the certificate sender's performance in retrieving the certificate revocation-information.

When the remote syslog server shares the certificate which has an OCSP responder URL, the client sends the server certificate to an external OCSP responder (CA) server. The CA server validates this certificate and confirms if it is a valid or a revoked certificate. In this case, the client does not have to maintain the revoked certificate list locally.

Import and Export Support for Certificates and Associated Key Pairs

As part of the CA authentication and enrollment process, the subordinate CA certificate (or certificate chain) and identity certificates can be imported in standard PEM (base64) format.

The complete identity information in a trust point can be exported to a file in the password-protected PKCS#12 standard format. It can be later imported to the same device (for example, after a system crash) or to a replacement device. The information in a PKCS#12 file consists of the RSA key pair, the identity certificate, and the CA certificate (or chain).

Guidelines and Limitations for PKI

PKI has the following configuration guidelines and limitations:

  • The maximum number of key pairs you can configure on a Cisco NX-OS device is 16.

  • The maximum number of trust points you can declare on a Cisco NX-OS device is 16.

  • The maximum number of identify certificates that you can configure on a Cisco NX-OS device are 16.

  • The maximum number of certificates in a CA certificate chain is 10.

  • The maximum number of trust points you can authenticate to a specific CA is 10.

  • Configuration rollbacks do not support the PKI configuration.

  • Beginning with Cisco NX-OS Release 9.3(5), Cisco NX-OS software supports NDcPP: OCSP for Syslog.

  • Beginning with Cisco NX-OS Release 10.3(3)F, Elliptic Curve Cyptography (ECC) key pair support is provided to generate and import the certificate on Cisco Nexus switches.


Note

If you are familiar with the Cisco IOS CLI, be aware that the Cisco NX-OS commands for this feature might differ from the Cisco IOS commands that you would use.

Default Settings for PKI

This table lists the default settings for PKI parameters.

Table 1. Default PKI Parameters

Parameters

Default

Trust point

None

RSA key pair

None

RSA key-pair label

Device FQDN

RSA key-pair modulus

512

RSA key-pair exportable

Enabled

Revocation check method

CRL

Configuring CAs and Digital Certificates

This section describes the tasks that you must perform to allow CAs and digital certificates on your Cisco NX-OS device to interoperate.

Configuring the Hostname and IP Domain Name

You must configure the hostname and IP domain name of the device if you have not yet configured them because the Cisco NX-OS software uses the fully qualified domain name (FQDN) of the device as the subject in the identity certificate. Also, the Cisco NX-OS software uses the device FQDN as a default key label when you do not specify a label during key-pair generation. For example, a certificate named DeviceA.example.com is based on a device hostname of DeviceA and a device IP domain name of example.com.


Caution

Changing the hostname or IP domain name after generating the certificate can invalidate the certificate.

Procedure

  Command or Action Purpose

Step 1

configure terminal

Example:

switch# configure terminal
switch(config)#

Enters global configuration mode.

Step 2

hostname hostname

Example:

switch(config)# hostname DeviceA

Configures the hostname of the device.

Step 3

ip domain-name name [use-vrf vrf-name]

Example:

DeviceA(config)# ip domain-name example.com

Configures the IP domain name of the device. If you do not specify a VRF name, the command uses the default VRF.

Step 4

exit

Example:

switch(config)# exit
switch#

Exits configuration mode.

Step 5

(Optional) show hosts

Example:

switch# show hosts
 (Optional)

Displays the IP domain name.

Step 6

(Optional) copy running-config startup-config

Example:

switch# copy running-config startup-config
 (Optional)

Copies the running configuration to the startup configuration.

Generating an RSA Key Pair

You can generate an RSA key pairs to sign and/or encrypt and decrypt the security payload during security protocol exchanges for applications. You must generate the RSA key pair before you can obtain a certificate for your device.

Beginning Cisco NX-OS Release 9.3(3), you must explicitly generate RSA key pairs before you associate the Cisco NX-OS device with a trust point CA. Prior to Cisco NX-OS Releases 9.3(3), if unavailable, the RSA key pairs would be auto generated.

Procedure

  Command or Action Purpose

Step 1

configure terminal

Example:

switch# configure terminal
switch(config)#

Enters global configuration mode.

Step 2

crypto key generate rsa [label label-string] [exportable] [modulus size]

Example:

switch(config)# crypto key generate rsa exportable

Generates an RSA key pair. The maximum number of key pairs on a device is 16.

The label string is alphanumeric, case sensitive, and has a maximum length of 64 characters. The default label string is the hostname and the FQDN separated by a period character (.).

Valid modulus values are 512, 768, 1024, 1536, and 2048. The default modulus size is 512.

Note

 

The security policy on the Cisco NX-OS device and on the CA (where enrollment is planned) should be considered when deciding the appropriate key modulus.

By default, the key pair is not exportable. Only exportable key pairs can be exported in the PKCS#12 format.

Caution

 

You cannot change the exportability of a key pair.

Step 3

exit

Example:

switch(config)# exit
switch#

Exits configuration mode.

Step 4

(Optional) show crypto key mypubkey rsa

Example:

switch# show crypto key mypubkey rsa
 (Optional)

Displays the generated key.

Step 5

(Optional) copy running-config startup-config

Example:

switch# copy running-config startup-config
 (Optional)

Copies the running configuration to the startup configuration.

Generating an ECC Key Pair

You can generate an ECC key pair to sign and/or encrypt and decrypt the security payload during security protocol exchanges for applications. You must generate the ECC key pair before you can obtain a certificate for your device. The ECC keys are stronger compared to RSA keys for a given length.

Beginning Cisco NX-OS Release 10.3(3)F, you can generate an ECC key pair to associate the Cisco NX-OS device with a trust point CA.

Procedure

  Command or Action Purpose

Step 1

configure terminal

Example:

switch# configure terminal
switch(config)#

Enters global configuration mode.

Step 2

crypto key generate ecc [label ecc-key-label] [exportable] [modulus size]

Example:

switch(config)# crypto key generate ecc exportable modulus 224

Generates an ECC key pair. The maximum number of key pairs on a device is 16.

The label string is alphanumeric, case sensitive, and has maximum length of 64 characters. The default label string is the hostname and the FQDN separated by a period character (.).

Valid modulus values are 224, 384, and 521. The default modulus size is 224.

Note

 

The security policy on the Cisco NX-OS device and on the CA (where enrollment is planned) should be considered when deciding the appropriate key modulus.

By default, the key pair is not exportable. Only exportable key pairs can be exported in the PKCS#12 format.

Caution

 

You cannot change the exportability of a key pair.

Step 3

no crypto key generate ecc [label ecc-key-label]

Example:

switch(config)# no crypto key generate ecc label label-name

Deletes the ECC key.

Step 4

exit

Example:

switch(config)# exit
switch#

Exits configuration mode.

Step 5

(Optional) show crypto key mypubkey ecc

Example:

switch# show crypto key mypubkey ecc
 (Optional)

Displays the generated ECC key.

Step 6

(Optional) copy running-config startup-config

Example:

switch# copy running-config startup-config
 (Optional)

Copies the running configuration to the startup configuration.

Creating a Trust Point CA Association

You must associate the Cisco NX-OS device with a trust point CA.

Before you begin

Generate the RSA key pair.

Procedure

  Command or Action Purpose

Step 1

configure terminal

Example:

switch# configure terminal
switch(config)#

Enters global configuration mode.

Step 2

crypto ca trustpoint name

Example:

switch(config)# crypto ca trustpoint admin-ca
switch(config-trustpoint)#

Declares a trust point CA that the device should trust and enters trust point configuration mode.

Note

 

The maximum number of trustpoints that can be configured is 50.

Step 3

cabundle baselabel

Example:

switch(config-trustpoint)# cabundle test

Groups the trustpoints under a specific CA bundle. The No form of this command detaches the trustpoints from the CA bundle. This command associates the trustpoints to an existing CA bundle and it does not configure any new CA bundle.

Step 4

enrollment terminal

Example:

switch(config-trustpoint)# enrollment terminal

Enables manual cut-and-paste certificate enrollment. The default is enabled.

Note

 

The Cisco NX-OS software supports only the manual cut-and-paste method for certificate enrollment.

Step 5

rsakeypair label

Example:

switch(config-trustpoint)# rsakeypair SwitchA

Specifies the label of the RSA key pair to associate to this trust point for enrollment.

Note

 

You can specify only one RSA key pair per CA.

Step 6

exit

Example:

switch(config-trustpoint)# exit
switch(config)#

Exits trust point configuration mode.

Step 7

(Optional) show crypto ca trustpoints

Example:

switch(config)# show crypto ca trustpoints
 (Optional)

Displays trust point information.

Step 8

(Optional) copy running-config startup-config

Example:

switch(config)# copy running-config startup-config
 (Optional)

Copies the running configuration to the startup configuration.

Configuring Certificate Mapping Filters

You can configure mapping filters to validate the CA certificates that are used for authentication. The mapping filters are used to match the CA certificate against a username.

Cisco NX-OS supports the following certificate mapping filters:

  • %username%—Substitutes the user’s login name.

  • %hostname%—Substitutes the peer hostname.

Before you begin

Configure a cert-store for certificate authentication.

Procedure

  Command or Action Purpose

Step 1

configure terminal

Example:

switch# configure terminal
switch(config)#

Enters global configuration mode.

Step 2

crypto certificatemap mapname map-name

Example:

switch(config)# crypto certificatemap mapname filtermap1

Creates a new filter map.

Step 3

filter [subject-name subject-name | altname-email e-mail-ID | altname-upn user-principal-name]

Example:

switch(config-certmap-filter)# filter altname-upn %username%@cisco.com

Configures one or more certificate mapping filters within the filter map. These certificate field attributes are supported in the filters: The validation passes if the certificate passes all of the filters configured in the map.

  • subject-name—The required subject name in the LDAP distinguished name (DN) string format. For example:
    filter subject-name CN=%username%
    or
    filter subject-name /C=IN/ST=KA/L=BLR/O=CISCO/OU=ABC/CN=%username%
  • altname-email—The e-mail address that must be present in the certificate as a subject alternative name. For example:
    filter altname-email %username%@cisco.com
  • altname-upn—The principal name that must be present in the certificate as a subject alternative name. For example:
    filter altname-upn %username%@%hostname%

The validation passes if the certificate passes all of the filters configured in the map.

Step 4

exit

Example:

switch(config-certmap-filter)# exit
switch(config)#

Exits certificate mapping filter configuration mode.

Step 5

(Optional) crypto cert ssh-authorize [default | issuer-CAname] [map map-name1 [map-name2]]

Example:

switch(config)# crypto cert ssh-authorize default map filtermap1
 (Optional)

Configures a certificate mapping filter for the Secure Shell (SSH) protocol. You can use the default filter map for SSH authorization or specify the issuer of the CA certificate. If you do not use the default map, you can specify one or two filter maps for authorization.

If you specify the issuer of the CA certificate, the certificate bound to the user account is validated as successful if it passes one of the configured maps.

Step 6

(Optional) show crypto certificatemap

Example:

switch(config)# show crypto certificatemap
 (Optional)

Displays the certificate mapping filters.

Step 7

(Optional) show crypto ssh-auth-map

Example:

switch(config)# show crypto ssh-auth-map
 (Optional)

Displays the mapping filters configured for SSH authentication.

Step 8

(Optional) copy running-config startup-config

Example:

switch(config)# copy running-config startup-config
 (Optional)

Copies the running configuration to the startup configuration.

Authenticating the CA

The configuration process of trusting a CA is complete only when the CA is authenticated to the Cisco NX-OS device. You must authenticate your Cisco NX-OS device to the CA by obtaining the self-signed certificate of the CA in PEM format, which contains the public key of the CA. Because the certificate of the CA is self-signed (the CA signs its own certificate) the public key of the CA should be manually authenticated by contacting the CA administrator to compare the fingerprint of the CA certificate.


Note

The CA that you are authenticating is not a self-signed CA when it is a subordinate CA to another CA, which itself may be a subordinate to yet another CA, and so on, finally ending in a self-signed CA. This type of CA certificate is called the CA certificate chain of the CA being authenticated. In this case, you must input the full list of the CA certificates of all the CAs in the certification chain during the CA authentication. The maximum number of certificates in a CA certificate chain is 10.

Before you begin

Create an association with the CA.

Obtain the CA certificate or CA certificate chain.

Procedure

  Command or Action Purpose

Step 1

configure terminal

Example:

switch# configure terminal
switch(config)#

Enters global configuration mode.

Step 2

crypto ca authenticate name pemfile uri0

Example:

switch(config)# crypto ca authenticate admin-ca
input (cut & paste) CA certificate (chain) in PEM format;
end the input with a line containing only END OF INPUT :
-----BEGIN CERTIFICATE-----
MIIC4jCCAoygAwIBAgIQBWDSiay0GZRPSRIljK0ZejANBgkqhkiG9w0BAQUFADCB
kDEgMB4GCSqGSIb3DQEJARYRYW1hbmRrZUBjaXNjby5jb20xCzAJBgNVBAYTAklO
MRIwEAYDVQQIEwlLYXJuYXRha2ExEjAQBgNVBAcTCUJhbmdhbG9yZTEOMAwGA1UE
ChMFQ2lzY28xEzARBgNVBAsTCm5ldHN0b3JhZ2UxEjAQBgNVBAMTCUFwYXJuYSBD
QTAeFw0wNTA1MDMyMjQ2MzdaFw0wNzA1MDMyMjU1MTdaMIGQMSAwHgYJKoZIhvcN
AQkBFhFhbWFuZGtlQGNpc2NvLmNvbTELMAkGA1UEBhMCSU4xEjAQBgNVBAgTCUth
cm5hdGFrYTESMBAGA1UEBxMJQmFuZ2Fsb3JlMQ4wDAYDVQQKEwVDaXNjbzETMBEG
A1UECxMKbmV0c3RvcmFnZTESMBAGA1UEAxMJQXBhcm5hIENBMFwwDQYJKoZIhvcN
AQEBBQADSwAwSAJBAMW/7b3+DXJPANBsIHHzluNccNM87ypyzwuoSNZXOMpeRXXI
OzyBAgiXT2ASFuUOwQ1iDM8rO/41jf8RxvYKvysCAwEAAaOBvzCBvDALBgNVHQ8E
BAMCAcYwDwYDVR0TAQH/BAUwAwEB/zAdBgNVHQ4EFgQUJyjyRoMbrCNMRU2OyRhQ
GgsWbHEwawYDVR0fBGQwYjAuoCygKoYoaHR0cDovL3NzZS0wOC9DZXJ0RW5yb2xs
L0FwYXJuYSUyMENBLmNybDAwoC6gLIYqZmlsZTovL1xcc3NlLTA4XENlcnRFbnJv
bGxcQXBhcm5hJTIwQ0EuY3JsMBAGCSsGAQQBgjcVAQQDAgEAMA0GCSqGSIb3DQEB
BQUAA0EAHv6UQ+8nE399Tww+KaGr0g0NIJaqNgLh0AFcT0rEyuyt/WYGPzksF9Ea
NBG7E0oN66zex0EOEfG1Vs6mXp1//w==
-----END CERTIFICATE-----
END OF INPUT
Fingerprint(s): MD5 Fingerprint=65:84:9A:27:D5:71:03:33:9C:12:23:92:38:6F:78:12
Do you accept this certificate? [yes/no]: yes

Prompts you to cut and paste the certificate of the CA. Use the same name that you used when declaring the CA.

Also validates and attaches the CA chain directly to the specified trust point.

The maximum number of trust points that you can authenticate to a specific CA is 10.

Note

 

For subordinate CA authentication, the Cisco NX-OS software requires the full chain of CA certificates ending in a self-signed CA because the CA chain is needed for certificate verification as well as for PKCS#12 format export.

Step 3

exit

Example:

switch(config)# exit
switch#

Exits configuration mode.

Step 4

(Optional) show crypto ca trustpoints

Example:

switch# show crypto ca trustpoints
 (Optional)

Displays the trust point CA information.

Step 5

(Optional) copy running-config startup-config

Example:

switch# copy running-config startup-config
 (Optional)

Copies the running configuration to the startup configuration.

Configuring Certificate Revocation Checking Methods

During security exchanges with a client (for example, an SSH user), the Cisco NX-OS device performs the certificate verification of the peer certificate sent by the client. The verification process may involve certificate revocation status checking.

You can configure the device to check the CRL downloaded from the CA. Downloading the CRL and checking locally does not generate traffic in your network. However, certificates can be revoked between downloads and your device would not be aware of the revocation.

Before you begin

Authenticate the CA.

Ensure that you have configured the CRL if you want to use CRL checking.

Procedure

  Command or Action Purpose

Step 1

configure terminal

Example:

switch# configure terminal
switch(config)#

Enters global configuration mode.

Step 2

crypto ca trustpoint name

Example:

switch(config)# crypto ca trustpoint admin-ca
switch(config-trustpoint)#

Specifies a trust point CA and enters trust point configuration mode.

Step 3

revocation-check {crl [none] | none}

Example:

switch(config-trustpoint)# revocation-check none

Configures the certificate revocation checking methods. The default method is crl .

The Cisco NX-OS software uses the certificate revocation methods in the order that you specify.

Step 4

exit

Example:

switch(config-trustpoint)# exit
switch(config)#

Exits trust point configuration mode.

Step 5

(Optional) show crypto ca trustpoints

Example:

switch(config)# show crypto ca trustpoints
 (Optional)

Displays the trust point CA information.

Step 6

(Optional) copy running-config startup-config

Example:

switch(config)# copy running-config startup-config
 (Optional)

Copies the running configuration to the startup configuration.

Generating Certificate Requests

You must generate a request to obtain identity certificates from the associated trust point CA for each of your device’s RSA key pairs. You must then cut and paste the displayed request into an e-mail or in a website form for the CA.

Before you begin

Create an association with the CA.

Obtain the CA certificate or CA certificate chain.

Procedure

  Command or Action Purpose

Step 1

configure terminal

Example:

switch# configure terminal
switch(config)#

Enters global configuration mode.

Step 2

crypto ca enroll name

Example:

switch(config)# crypto ca enroll admin-ca
Create the certificate request ..
 Create a challenge password. You will need to verbally provide this
  password to the CA Administrator in order to revoke your certificate.
  For security reasons your password will not be saved in the configuration.
  Please make a note of it.
  Password:nbv123
 The subject name in the certificate will be: DeviceA.cisco.com
 Include the switch serial number in the subject name? [yes/no]: no
 Include an IP address in the subject name [yes/no]: yes
ip address:172.22.31.162
 The certificate request will be displayed...
-----BEGIN CERTIFICATE REQUEST-----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=
-----END CERTIFICATE REQUEST-----

Generates a certificate request for an authenticated CA.

Note

 

You must remember the challenge password. It is not saved with the configuration. You must enter this password if your certificate needs to be revoked.

Step 3

exit

Example:

switch(config-trustpoint)# exit
switch(config)#

Exits trust point configuration mode.

Step 4

(Optional) show crypto ca certificates

Example:

switch(config)# show crypto ca certificates
 (Optional)

Displays the CA certificates.

Step 5

(Optional) copy running-config startup-config

Example:

switch(config)# copy running-config startup-config
 (Optional)

Copies the running configuration to the startup configuration.

Installing Identity Certificates

You can receive the identity certificate from the CA by e-mail or through a web browser in base64 encoded text form. You must install the identity certificate from the CA by cutting and pasting the encoded text.

Before you begin

Create an association with the CA.

Obtain the CA certificate or CA certificate chain.

Procedure

  Command or Action Purpose

Step 1

configure terminal

Example:

switch# configure terminal
switch(config)#

Enters global configuration mode.

Step 2

crypto ca import name certificate

Example:

switch(config)# crypto ca import admin-ca certificate
input (cut & paste) certificate in PEM format:
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----

Prompts you to cut and paste the identity certificate for the CA named admin-ca.

The maximum number of identify certificates that you can configure on a device is 16.

Step 3

exit

Example:

switch(config)# exit
switch#

Exits configuration mode.

Step 4

(Optional) show crypto ca certificates

Example:

switch# show crypto ca certificates
 (Optional)

Displays the CA certificates.

Step 5

(Optional) copy running-config startup-config

Example:

switch# copy running-config startup-config
 (Optional)

Copies the running configuration to the startup configuration.

Ensuring Trust Point Configurations Persist Across Reboots

You can ensure that the trustpoint configuration persists across Cisco NX-OS device reboots.

The trust point configuration is a normal Cisco NX-OS device configuration that persists across system reboots only if you copy it explicitly to the startup configuration. The certificates, key pairs, and CRL associated with a trust point are automatically persistent if you have already copied the trust point configuration in the startup configuration. Conversely, if the trust point configuration is not copied to the startup configuration, the certificates, key pairs, and CRL associated with it are not persistent since they require the corresponding trust point configuration after a reboot. Always copy the running configuration to the startup configuration to ensure that the configured certificates, key pairs, and CRLs are persistent. Also, save the running configuration after deleting a certificate or key pair to ensure that the deletions permanent.

The certificates and CRL associated with a trust point automatically become persistent when imported (that is, without explicitly copying to the startup configuration) if the specific trust point is already saved in startup configuration.

We recommend that you create a password-protected backup of the identity certificates and save it to an external server.


Note

Copying the configuration to an external server does include the certificates and key pairs.

Exporting Identity Information in PKCS 12 Format

You can export the identity certificate along with the RSA key pair and CA certificate (or the entire chain in the case of a subordinate CA) of a trust point to a PKCS#12 file for backup purposes. You can import the certificate and RSA key pair to recover from a system crash on your device or when you replace the supervisor modules.


Note

You can use only the bootflash:filename format when specifying the export URL.

Before you begin

Authenticate the CA.

Install an identity certificate.

Procedure

  Command or Action Purpose

Step 1

configure terminal

Example:

switch# configure terminal
switch(config)#

Enters global configuration mode.

Step 2

crypto ca export name pkcs12 bootflash:filename password

Example:

switch(config)# crypto ca export admin-ca pkcs12 bootflash:adminid.p12 nbv123

Exports the identity certificate and associated key pair and CA certificates for a trust point CA. The password is alphanumeric, case sensitive, and has a maximum length of 128 characters.

Step 3

exit

Example:

switch(config)# exit
switch#

Exits configuration mode.

Step 4

copy booflash:filename scheme://server/ [url /]filename

Example:

switch# copy bootflash:adminid.p12 tftp:adminid.p12

Copies the PKCS#12 format file to a remote server.

For the scheme argument, you can enter tftp: , ftp: , scp: , or sftp: . The server argument is the address or name of the remote server, and the url argument is the path to the source file on the remote server.

The server, url, and filename arguments are case sensitive.

Importing Identity Information in PKCS 12 or PKCS 7 Format

You can import the certificate and RSA key pair to recover from a system crash on your device or when you replace the supervisor modules.


Note

You can use only the bootflash:filename format when specifying the import URL.

Before you begin

Ensure that the trust point is empty by checking that no RSA key pair is associated with it and no CA is associated with the trust point using CA authentication.

Procedure

  Command or Action Purpose

Step 1

copy scheme:// server/[url /]filename bootflash:filename

Example:

switch# copy tftp:adminid.p12 bootflash:adminid.p12

Copies the PKCS#12 format file from the remote server.

For the scheme argument, you can enter tftp: , ftp: , scp: , or sftp: . The server argument is the address or name of the remote server, and the url argument is the path to the source file on the remote server.

The server, url, and filename arguments are case sensitive.

Step 2

configure terminal

Example:

switch# configure terminal
switch(config)#

Enters global configuration mode.

Step 3

crypto ca import name [pksc12 | pkcs7] bootflash:filename

Example:

switch(config)# crypto ca import admin-ca pkcs12 bootflash:adminid.p12 nbv123

Imports the identity certificate and associated key pair and CA certificates for trust point CA.

Step 4

exit

Example:

switch(config)# exit
switch#

Exits configuration mode.

Step 5

(Optional) show crypto ca certificates

Example:

switch# show crypto ca certificates
 (Optional)

Displays the CA certificates.

Step 6

(Optional) copy running-config startup-config

Example:

switch# copy running-config startup-config
 (Optional)

Copies the running configuration to the startup configuration.

Configuring a CRL

You can manually configure CRLs that you have downloaded from the trust points. The Cisco NX-OS software caches the CRLs in the device bootflash (cert-store). During the verification of a peer certificate, the Cisco NX-OS software checks the CRL from the issuing CA only if you have downloaded the CRL to the device and you have configured certificate revocation checking to use the CRL.

Before you begin

Ensure that you have enabled certificate revocation checking.

Procedure

  Command or Action Purpose

Step 1

copy scheme:[//server/[url /]]filename bootflash:filename

Example:

switch# copy tftp:adminca.crl bootflash:adminca.crl

Downloads the CRL from a remote server.

For the scheme argument, you can enter tftp: , ftp: , scp: , or sftp: . The server argument is the address or name of the remote server, and the url argument is the path to the source file on the remote server.

The server, url, and filename arguments are case sensitive.

Step 2

configure terminal

Example:

switch# configure terminal
switch(config)#

Enters global configuration mode.

Step 3

crypto ca crl request name bootflash:filename

Example:

switch(config)# crypto ca crl request admin-ca bootflash:adminca.crl

Configures or replaces the current CRL with the one specified in the file.

Step 4

exit

Example:

switch(config)# exit
switch#

Exits configuration mode.

Step 5

(Optional) show crypto ca crl name

Example:

switch# show crypto ca crl admin-ca
 (Optional)

Displays the CA CRL information.

Step 6

(Optional) copy running-config startup-config

Example:

switch# copy running-config startup-config
 (Optional)

Copies the running configuration to the startup configuration.

Deleting Certificates from the CA Configuration

You can delete the identity certificates and CA certificates that are configured in a trust point. You must first delete the identity certificate, followed by the CA certificates. After deleting the identity certificate, you can disassociate the RSA key pair from a trust point. You must delete certificates to remove expired or revoked certificates, certificates that have compromised (or suspected to be compromised) key pairs, or CAs that are no longer trusted.

Procedure

  Command or Action Purpose

Step 1

configure terminal

Example:

switch# configure terminal
switch(config)#

Enters global configuration mode.

Step 2

crypto ca trustpoint name

Example:

switch(config)# crypto ca trustpoint admin-ca
switch(config-trustpoint)#

Specifies a trust point CA and enters trust point configuration mode.

Step 3

delete ca-certificate

Example:

switch(config-trustpoint)# delete ca-certificate

Deletes the CA certificate or certificate chain.

Step 4

delete certificate [force]

Example:

switch(config-trustpoint)# delete certificate

Deletes the identity certificate.

You must use the force option if the identity certificate you want to delete is the last certificate in a certificate chain or only identity certificate in the device. This requirement ensures that you do not mistakenly delete the last certificate in a certificate chain or only the identity certificate and leave the applications (such as SSH) without a certificate to use.

Step 5

exit

Example:

switch(config-trustpoint)# exit
switch(config)#

Exits trust point configuration mode.

Step 6

(Optional) show crypto ca certificates [name]

Example:

switch(config)# show crypto ca certificates admin-ca
 (Optional)

Displays the CA certificate information.

Step 7

(Optional) copy running-config startup-config

Example:

switch(config)# copy running-config startup-config
 (Optional)

Copies the running configuration to the startup configuration.

Deleting RSA Key Pairs from a Cisco NX-OS Device

You can delete the RSA key pairs from a Cisco NX-OS device if you believe the RSA key pairs were compromised in some way and should no longer be used.


Note

After you delete RSA key pairs from a device, ask the CA administrator to revoke your device’s certificates at the CA. You must supply the challenge password that you created when you originally requested the certificates.

Procedure

  Command or Action Purpose

Step 1

configure terminal

Example:

switch# configure terminal
switch(config)#

Enters global configuration mode.

Step 2

crypto key zeroize rsa label

Example:

switch(config)# crypto key zeroize rsa MyKey

Deletes the RSA key pair.

Step 3

exit

Example:

switch(config)# exit
switch#

Exits configuration mode.

Step 4

(Optional) show crypto key mypubkey rsa

Example:

switch# show crypto key mypubkey rsa
 (Optional)

Displays the RSA key pair configuration.

Step 5

(Optional) copy running-config startup-config

Example:

switch# copy running-config startup-config
 (Optional)

Copies the running configuration to the startup configuration.

Verifying the PKI Configuration

To display PKI configuration information, perform one of the following tasks:

Command

Purpose

show crypto key mypubkey rsa

Displays information about the RSA public keys generated on the Cisco NX-OS device.

show crypto ca certificates

Displays information about CA and identity certificates.

show crypto ca crl

Displays information about CA CRLs.

show crypto ca trustpoints

Displays information about CA trust points.

Configuration Examples for PKI

This section shows examples of the tasks that you can use to configure certificates and CRLs on Cisco NX-OS devices using a Microsoft Windows Certificate server.


Note

You can use any type of certificate server to generate digital certificates. You are not limited to using the Microsoft Windows Certificate server.

Configuring Certificates on a Cisco NX-OS Device

To configure certificates on a Cisco NX-OS device, follow these steps:

Procedure

Step 1

Configure the device FQDN. 

switch# configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
switch(config)# hostname Device-1
Device-1(config)#

Step 2

Configure the DNS domain name for the device. 

Device-1(config)# ip domain-name cisco.com

Step 3

Create a trust point. 

Device-1(config)# crypto ca trustpoint myCA
Device-1(config-trustpoint)# exit
Device-1(config)# show crypto ca trustpoints
trustpoint: myCA; key:
revokation methods:  crl

Step 4

Create an RSA key pair for the device. 

Device-1(config)# crypto key generate rsa label myKey exportable modulus 1024
Device-1(config)# show crypto key mypubkey rsa
key label: myKey
key size: 1024
exportable: yes

Step 5

Associate the RSA key pair to the trust point. 

Device-1(config)# crypto ca trustpoint myCA
Device-1(config-trustpoint)# rsakeypair myKey
Device-1(config-trustpoint)# exit
Device-1(config)# show crypto ca trustpoints
trustpoint: myCA; key: myKey
revokation methods:  crl

Step 6

Download the CA certificate from the Microsoft Certificate Service web interface.

Step 7

Authenticate the CA that you want to enroll to the trust point. 

Device-1(config)# crypto ca authenticate myCA
input (cut & paste) CA certificate (chain) in PEM format;
end the input with a line containing only END OF INPUT :
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
END OF INPUT
Fingerprint(s): MD5 Fingerprint=65:84:9A:27:D5:71:03:33:9C:12:23:92:38:6F:78:12
Do you accept this certificate? [yes/no]:y

Device-1(config)# show crypto ca certificates
Trustpoint: myCA
CA certificate 0:
subject= /emailAddress=admin@yourcompany.com/C=IN/ST=Karnataka/
L=Bangalore/O=Yourcompany/OU=netstorage/CN=Aparna CA
issuer= /emailAddress=admin@yourcompany.com/C=IN/ST=Karnataka/
L=Bangalore/O=Yourcompany/OU=netstorage/CN=Aparna CA
serial=0560D289ACB419944F4912258CAD197A
notBefore=May  3 22:46:37 2005 GMT
notAfter=May  3 22:55:17 2007 GMT
MD5 Fingerprint=65:84:9A:27:D5:71:03:33:9C:12:23:92:38:6F:78:12
purposes: sslserver sslclient ike

Step 8

Generate a request certificate to use to enroll with a trust point. 

Device-1(config)# crypto ca enroll myCA
 Create the certificate request ..
 Create a challenge password. You will need to verbally provide this
  password to the CA Administrator in order to revoke your certificate.
  For security reasons your password will not be saved in the configuration.
  Please make a note of it.
  Password: nbv123
 The subject name in the certificate will be: Device-1.cisco.com
 Include the switch serial number in the subject name? [yes/no]: no
 Include an IP address in the subject name [yes/no]: yes
ip address: 10.10.1.1
 The certificate request will be displayed...
-----BEGIN CERTIFICATE REQUEST-----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=
-----END CERTIFICATE REQUEST-----

Step 9

Request an identity certificate from the Microsoft Certificate Service web interface.

Step 10

Import the identity certificate. 

Device-1(config)# crypto ca import myCA certificate
input (cut & paste) certificate in PEM format:
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
Device-1(config)# exit
Device-1#

Step 11

Verify the certificate configuration.

Step 12

Save the certificate configuration to the startup configuration.

Downloading a CA Certificate

To download a CA certificate from the Microsoft Certificate Services web interface, follow these steps:

Procedure

Step 1

From the Microsoft Certificate Services web interface, click Retrieve the CA certificate or certificate revocation task and click Next.

Step 2

From the display list, choose the CA certificate file to download from the displayed list. Then click Base 64 encoded and click Download CA certificate.

Step 3

Click Open in the File Download dialog box.

Step 4

In the Certificate dialog box, click Copy to File and click OK.

Step 5

From the Certificate Export Wizard dialog box, choose the Base-64 encoded X.509 (CER) and click Next.

Step 6

In the File name: text box on the Certificate Export Wizard dialog box, enter the destination file name and click Next.

Step 7

In the Certificate Export Wizard dialog box, click Finish.

Step 8

Enter the Microsoft Windows type command to display the CA certificate stored in Base-64 (PEM) format.

Requesting an Identity Certificate

To request an identify certificate from a Microsoft Certificate server using a PKCS#12 certificate signing request (CRS), follow these steps:

Procedure

Step 1

From the Microsoft Certificate Services web interface, click Request a certificate and click Next.

Step 2

Click Advanced request and click Next.

Step 3

Click Submit a certificate request using a base64 encoded PKCS#10 file or a renewal request using a base64 encoded PKCS#7 file and click Next.

Step 4

In the Saved Request text box, paste the base64 PKCS#10 certificate request and click Next. The certificate request is copied from the Cisco NX-OS device console.

Step 5

Wait one or two days until the certificate is issued by the CA administrator.

Step 6

Note that the CA administrator approves the certificate request.

Step 7

From the Microsoft Certificate Services web interface, click Check on a pending certificate and click Next.

Step 8

Choose the certificate request that you want to check and click Next.

Step 9

Click Base 64 encoded and click Download CA certificate.

Step 10

In the File Download dialog box, click Open.

Step 11

In the Certificate box, click Details tab and click Copy to File.... In the Certificate Export Dialog box, click Base-64 encoded X.509 (.CER), and click Next.

Step 12

In the File name: text box on the Certificate Export Wizard dialog box, enter the destination file name and click Next.

Step 13

Click Finish.

Step 14

Enter the Microsoft Windows type command to display the identity certificate in base64-encoded format.

Revoking a Certificate

To revoke a certificate using the Microsoft CA administrator program, follow these steps:

Procedure

Step 1

From the Certification Authority tree, click Issued Certificates folder. From the list, right-click the certificate that you want to revoke.

Step 2

Choose All Tasks > Revoke Certificate.

Step 3

From the Reason code drop-down list, choose a reason for the revocation and click Yes.

Step 4

Click the Revoked Certificates folder to list and verify the certificate revocation.

Generating and Publishing the CRL

To generate and publish the CRL using the Microsoft CA administrator program, follow these steps:

Procedure

Step 1

From the Certification Authority screen, choose Action > All Tasks > Publish.

Step 2

In the Certificate Revocation List dialog box, click Yes to publish the latest CRL.

Downloading the CRL

To download the CRL from the Microsoft CA website, follow these steps:

Procedure

Step 1

From the Microsoft Certificate Services web interface, click Retrieve the CA certificate or certificate revocation list and click Next.

Step 2

Click Download latest certificate revocation list.

Step 3

In the File Download dialog box, click Save.

Step 4

In the Save As dialog box, enter the destination file name and click Save.

Step 5

Enter the Microsoft Windows type command to display the CRL.

Importing the CRL

To import the CRL to the trust point corresponding to the CA, follow these steps:

Procedure

Step 1

Copy the CRL file to the Cisco NX-OS device bootflash. 

Device-1# copy tftp:apranaCA.crl bootflash:aparnaCA.crl

Step 2

Configure the CRL. 


Device-1# configure terminal
Device-1(config)# crypto ca crl request myCA bootflash:aparnaCA.crl
Device-1(config)#

Step 3

Display the contents of the CRL. 


Device-1(config)# show crypto ca crl myCA
Trustpoint: myCA
CRL:
Certificate Revocation List (CRL):
        Version 2 (0x1)
        Signature Algorithm: sha1WithRSAEncryption
        Issuer: /emailAddress=admin@yourcompany.com/C=IN/ST=Karnatak
Yourcompany/OU=netstorage/CN=Aparna CA
        Last Update: Nov 12 04:36:04 2005 GMT
        Next Update: Nov 19 16:56:04 2005 GMT
        CRL extensions:
            X509v3 Authority Key Identifier:
            keyid:27:28:F2:46:83:1B:AC:23:4C:45:4D:8E:C9:18:50:1
            1.3.6.1.4.1.311.21.1:
                ...
Revoked Certificates:
    Serial Number: 611B09A1000000000002
        Revocation Date: Aug 16 21:52:19 2005 GMT
Serial Number: 4CDE464E000000000003
        Revocation Date: Aug 16 21:52:29 2005 GMT
    Serial Number: 4CFC2B42000000000004
        Revocation Date: Aug 16 21:52:41 2005 GMT
    Serial Number: 6C699EC2000000000005
        Revocation Date: Aug 16 21:52:52 2005 GMT
    Serial Number: 6CCF7DDC000000000006
        Revocation Date: Jun  8 00:12:04 2005 GMT
    Serial Number: 70CC4FFF000000000007
        Revocation Date: Aug 16 21:53:15 2005 GMT
    Serial Number: 4D9B1116000000000008
        Revocation Date: Aug 16 21:53:15 2005 GMT
    Serial Number: 52A80230000000000009
        Revocation Date: Jun 27 23:47:06 2005 GMT
        CRL entry extensions:
            X509v3 CRL Reason Code:
            CA Compromise
Serial Number: 5349AD4600000000000A
        Revocation Date: Jun 27 23:47:22 2005 GMT
        CRL entry extensions:
            X509v3 CRL Reason Code:
            CA Compromise
Serial Number: 53BD173C00000000000B
        Revocation Date: Jul  4 18:04:01 2005 GMT
        CRL entry extensions:
            X509v3 CRL Reason Code:
            Certificate Hold
Serial Number: 591E7ACE00000000000C
        Revocation Date: Aug 16 21:53:15 2005 GMT
    Serial Number: 5D3FD52E00000000000D
        Revocation Date: Jun 29 22:07:25 2005 GMT
        CRL entry extensions:
            X509v3 CRL Reason Code:
            Key Compromise
Serial Number: 5DAB771300000000000E
        Revocation Date: Jul 14 00:33:56 2005 GMT
    Serial Number: 5DAE53CD00000000000F
        Revocation Date: Aug 16 21:53:15 2005 GMT
    Serial Number: 5DB140D3000000000010
        Revocation Date: Aug 16 21:53:15 2005 GMT
    Serial Number: 5E2D7C1B000000000011
        Revocation Date: Jul  6 21:12:10 2005 GMT
        CRL entry extensions:
            X509v3 CRL Reason Code:
            Cessation Of Operation
Serial Number: 16DB4F8F000000000012
        Revocation Date: Aug 16 21:53:15 2005 GMT
    Serial Number: 261C3924000000000013
        Revocation Date: Aug 16 21:53:15 2005 GMT
    Serial Number: 262B5202000000000014
        Revocation Date: Jul 14 00:33:10 2005 GMT
    Serial Number: 2634C7F2000000000015
        Revocation Date: Jul 14 00:32:45 2005 GMT
    Serial Number: 2635B000000000000016
        Revocation Date: Jul 14 00:31:51 2005 GMT
    Serial Number: 26485040000000000017
        Revocation Date: Jul 14 00:32:25 2005 GMT
    Serial Number: 2A276357000000000018
Revocation Date: Aug 16 21:53:15 2005 GMT
    Serial Number: 3F88CBF7000000000019
        Revocation Date: Aug 16 21:53:15 2005 GMT
    Serial Number: 6E4B5F5F00000000001A
        Revocation Date: Aug 16 21:53:15 2005 GMT
    Serial Number: 725B89D800000000001B
        Revocation Date: Aug 16 21:53:15 2005 GMT
    Serial Number: 735A887800000000001C
        Revocation Date: Aug 16 21:53:15 2005 GMT
    Serial Number: 148511C700000000001D
        Revocation Date: Aug 16 21:53:15 2005 GMT
    Serial Number: 14A7170100000000001E
        Revocation Date: Aug 16 21:53:15 2005 GMT
    Serial Number: 14FC45B500000000001F
        Revocation Date: Aug 17 18:30:42 2005 GMT
    Serial Number: 486CE80B000000000020
        Revocation Date: Aug 17 18:30:43 2005 GMT
    Serial Number: 4CA4A3AA000000000021
        Revocation Date: Aug 17 18:30:43 2005 GMT
    Serial Number: 1AA55C8E00000000002F
        Revocation Date: Sep  5 17:07:06 2005 GMT
    Serial Number: 3F0845DD00000000003F
        Revocation Date: Sep  8 20:24:32 2005 GMT
    Serial Number: 3F619B7E000000000042
        Revocation Date: Sep  8 21:40:48 2005 GMT
    Serial Number: 6313C463000000000052
        Revocation Date: Sep 19 17:37:18 2005 GMT
    Serial Number: 7C3861E3000000000060
        Revocation Date: Sep 20 17:52:56 2005 GMT
    Serial Number: 7C6EE351000000000061
        Revocation Date: Sep 20 18:52:30 2005 GMT
    Serial Number: 0A338EA1000000000074   <-- Revoked identity certificate
        Revocation Date: Nov 12 04:34:42 2005 GMT
    Signature Algorithm: sha1WithRSAEncryption
        0b:cb:dd:43:0a:b8:62:1e:80:95:06:6f:4d:ab:0c:d8:8e:32:
        44:8e:a7:94:97:af:02:b9:a6:9c:14:fd:eb:90:cf:18:c9:96:
        29:bb:57:37:d9:1f:d5:bd:4e:9a:4b:18:2b:00:2f:d2:6e:c1:
        1a:9f:1a:49:b7:9c:58:24:d7:72

Note

 

The identity certificate for the device that was revoked (serial number 0A338EA1000000000074) is listed at the end.

Additional References for PKI

This section includes additional information related to implementing PKI.

Related Documents for PKI

Related Topic

Document Title

Cisco NX-OS Licensing

Cisco NX-OS Licensing Guide

VRF configuration

Cisco Nexus 9000 Series NX-OS Unicast Routing Configuration Guide

Standards for PKI

Standards

Title

No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.

—

Resource Public Key Infrastructure (RPKI)

RPKI is a globally distributed database that contains information mapping BGP (internet) prefixes to their authorized origin-AS numbers. To validate the origin-AS of BGP paths, routers running BGP can connect to RPKI caches.

The RPKI-Cache-to-Router connectivity can be many-to-many, one RPKI cache can provide origin-AS validation data to multiple routers and one router can be connected to multiple RPKI caches. A router connects to RPKI caches to download information to build a special RPKI database that can be used by BGP to validate the origin-AS numbers for the internet routing table.

The RPKI database is a set of Route-Origin-Attestation (ROA) objects aggregated from the different RPKI caches to which BGP connects. ROA objects provide a mapping between a BGP prefix-block, and an AS number authorized to originate that block.

RPKI Configuration

RPKI configuration is categorized as:

  • commands for connecting to RPKI Caches.

  • commands for marking incoming prefixes with RPKI validation state.

  • commands for using RPKI validation state in BGP best-path computation.

  • commands for dropping out or manipulating prefixes with specific validation states using route-map.

Commands for connecting to RPKI caches

RPKI cache configuration is done in a new rpki-cache submode under the router-bgp submode. This is like configuring BGP peers under the default VRF. The submode is entered by using the "rpki cache <IP address>" command. When you enter the submode, various parameters for the RPKI cache can be configured. 

router bgp 100
 rpki cache 147.28.0.11   
    description        A description to identify the cache
    shutdown           Shutdown the cache
    transport tcp port Transport port on which cache is listening
    vrf                Vrf in which RPKI cache is reachable
    refresh-interval   Specify periodic wait time between cache poll attempts   
    retry-interval     Specify wait time before retrying failed serial or reset query
    expiry-interval    Specify how long to use current data while unable to perform successful query

Note

Unless transport TCP port is explicitly configured, BGP will connect to RPKI cache on RPKI-RTR port 323.

Unless explicitly configured, all intervals will be determined as suggested by the RPKI Cache in End of Data PDU.

Commands for marking incoming prefixes with RPKI validation state

There are knobs that control the behavior of RPKI prefix validation processing. These knobs can be configured at the address-family level.

  • origin-as validate - Configured at the address-family level enables eBGP path validation against ROA database. By default, this is disabled.


    Note

    This command has no bearing on iBGP paths. The iBGP paths are not validated against ROA database. The only way to mark path validation state on iBGP paths is receiving the BGP Prefix Origin Validation State Extended Community, and is done by default without configuring any command.

  • origin-as validate signal ibgp - Configured at the address-family level enables the iBGP signalling of validity state through BGP Prefix Origin Validation State Extended Community.

Commands for using RPKI validation state in BGP best-path-computation

There are commands to control the behavior of RPKI prefix validation processing. These commands can be configured at the address-family level.

  • bestpath origin-as use-validity - Configured at the address-family level enables the validity states of BGP paths to affect the path’s preference in the BGP bestpath process. By default, this is disabled.

  • bestpath origin-as allow invalid - Configured at the address-family level allows all "invalid" paths to be considered for BGP bestpath computation (all such paths are not bestpath candidates if best-path origin-as validate is configured). By default, this is disabled.

Commands for dropping out or manipulating prefixes with specific validation states using route-map

The following is the command for dropping out or manipulating prefixes with specific validation states using route-map:

route-map sample1 permit 10
  match rpki {not-found | invalid | valid}

The parameters of the match rpki command are described as follows:

  • not-found - This origin-AS is unknown in the RPKI database.

  • invalid - This is an invalid origin-AS in the RPKI database.

    valid - This is a valid origin-AS in the RPKI database.

This match clause is relevant for inbound route-maps only.

For iBGP learnt paths, the incoming BGP Prefix Origin Validation State Extended Community in the update will be compared against this route-map clause.

For eBGP learnt paths, the validation state obtained by ROA database lookup will be compared against this route-map clause.

While prefixes marked as validation-state invalid are rendered ineffective by not being considered for best-path computation in BGP, an administrator may decide to drop such prefixes altogether to save system memory. The following inbound route-map is recommended for this purpose: 

route-map sample deny 10
match rpki invalid
route-map sample permit 20

RPKI Show Commands

To display RPKI configuration information, perform one of the following tasks:

Command

Purpose

show bgp rpki summary

Displays an overview of RPKI statistics including the number of RPKI caches.
show bgp rpki table {ipv4 | ipv6} {IP address/masklength}

Displays information about the current RPKI ROA database. With no options specified, the command shows the IPv4 ROA database. With the IPv6 option (show bgp rpki table ipv6), the command shows the IPv6 ROA database. ROAs that are received from a cache that is temporarily down (due to connectivity issues, for example) are displayed with (*). These ROAs will be removed from the RPKI database if the cache session does not establish within the purge-time for that cache.

If an ROA prefix-block is specified after the table show command (for example, show bgp rpki table 67.21.36.0/24 max 24), then that specific ROA entry is displayed in detail, if the ROA exists.

Note

 

One ROA (IP address/min-max) can have multiple origin ASs and can be sourced from multiple caches.
show bgp rpki cache {IP address}

Displays a summary listing of all the caches that are configured and their parameters, such as show bgp summary.

If a cache IP address is specified with the previous command, then detailed information is shown for that cache.
show bgp {ipv4 unicast | ipv6 unicast} origin-as validity-state {valid | invalid | unknown}

Displays information about BGP. This command has new options to filter the BGP table output based on path (validation_state). Specify a validity state (valid, invalid, or unknown) with this command to filter the relevant information from the BGP table, and only the BGP paths matching that validity-state are displayed.

RPKI Clear Commands

The following is the RPKI Clear command:

  • clear bgp rpki cache * - This command resets the transport sessions of all configured RPKI caches and immediately purges the RPKI database of all IPv4 and IPv6 ROAs received from all caches.

RPKI Debug and Event History Commands

The following are the RPKI Debug and Event History commands:

  • debug bgp rpki - This command turns on debugging for all RPKI related operations excluding prefix-validation. This includes debugging events such as RPKI cache connectivity, protocol state-machine for the RPKI caches, and RPKI database events such as ROA insertion or deletion.

  • sh bgp event-history rpki - This command dumps high level information about RPKI.