FlexVPN and Internet Key Exchange Version 2 Configuration Guide, Cisco IOS Release 15SY
Configuring Internet Key Exchange Version 2 (IKEv2) and FlexVPN Site-to-Site
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Configuring Internet Key Exchange Version 2 (IKEv2) and FlexVPN Site-to-Site

Contents

Configuring Internet Key Exchange Version 2 and FlexVPN Site-to-Site

Last Updated: October 15, 2012

This module contains information about and instructions for configuring basic and advanced Internet Key Exchange Version 2 (IKEv2) and FlexVPN site-to-site. The tasks and configuration examples for IKEv2 in this module are divided as follows:

  • Basic IKEv2--Provides information about basic IKEv2 commands, IKEv2 smart defaults, basic IKEv2 profile, and IKEv2 key ring.
  • Advanced IKEv2--Provides information about global IKEv2 commands and how to override IKEv2 smart defaults.

Note


Security threats, as well as the cryptographic technologies to help protect against them, are constantly changing. For more information about the latest Cisco cryptographic recommendations, see the Next Generation Encryption (NGE) white paper.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.

Prerequisites for Configuring Internet Key Exchange Version 2

You should be familiar with the concepts and tasks described in the "Configuring Security for VPNs with IPsec" module.

Restrictions for Configuring Internet Key Exchange Version 2

You cannot configure an option that is not supported on a specific platform. For example, in a security protocol, the capability of the hardware-crypto engine is important, and you cannot specify the Triple Data Encryption Standard (3DES) or the Advanced Encryption Standard (AES) type of encryption transform in a nonexportable image, or specify an encryption algorithm that a crypto engine does not support.

Information About Internet Key Exchange Version 2

IKEv2 Supported Standards

Cisco implements the IP Security (IPsec) Protocol standard for use in Internet Key Exchange Version 2 (IKEv2).


Note


Cisco no longer recommends using DES or MD5 (including HMAC variant); instead, you should use AES and SHA-256. For more information about the latest Cisco cryptographic recommendations, see the Next Generation Encryption (NGE) white paper.

The component technologies implemented in IKEv2 are as follows:

  • AES-CBC--Advanced Encryption Standard-Cipher Block Chaining
  • SHA (HMAC variant)--Secure Hash Algorithm
  • Diffie-Hellman--A public-key cryptography protocol
  • DES--Data Encryption Standard (No longer recommended)
  • MD5 (HMAC [Hash-based Message Authentication Code] variant)--Message digest algorithm 5 (No longer recommended)

For more information about supported standards and component technologies, see the "Supported Standards for Use with IKE" section in the "Configuring Internet Key Exchange for IPsec VPNs" module in the Internet Key Exchange for IPsec VPNs Configuration Guide.

Benefits of IKEv2

Dead Peer Detection and Network Address Translation-Traversal

Internet Key Exchange Version 2 (IKEv2) provides built-in support for Dead Peer Detection (DPD) and Network Address Translation-Traversal (NAT-T).

Certificate URLs

Certificates can be referenced through a URL and hash, instead of being sent within IKEv2 packets, to avoid fragmentation.

Denial of Service Attack Resilience

IKEv2 does not process a request until it determines the requester, which addresses to some extent the Denial of Service (DoS) problems in IKEv1, which can be spoofed into performing substantial cryptographic (expensive) processing from false locations.

EAP Support

IKEv2 allows the use of Extensible Authentication Protocol (EAP) for authentication.

Multiple Crypto Engines

If your network has both IPv4 and IPv6 traffic and you have multiple crypto engines, choose one of the following configuration options:

  • One engine handles IPv4 traffic and the other engine handles IPv6 traffic.
  • One engine handles both IPv4 and IPv6 traffic.

Reliability and State Management (Windowing)

IKEv2 uses sequence numbers and acknowledgments to provide reliability, and mandates some error-processing logistics and shared state management.

Internet Key Exchange Version 2 CLI Constructs

IKEv2 Proposal

An Internet Key Exchange Version 2 (IKEv2) proposal is a collection of transforms used in the negotiation of Internet Key Exchange (IKE) security associations (SAs) as part of the IKE_SA_INIT exchange. The transform types used in the negotiation are as follows:

  • Encryption algorithm
  • Integrity algorithm
  • Pseudo-Random Function (PRF) algorithm
  • Diffie-Hellman (DH) group

See the "IKEv2 Smart Defaults" section for information about the default IKEv2 proposal. See the "Configuring Advanced IKEv2 CLI Constructs" section for information about how to override the default IKEv2 proposal and to define new proposals.

IKEv2 Policy

An IKEv2 policy contains proposals that are used to negotiate the encryption, integrity, PRF algorithms, and DH group in the IKE_SA_INIT exchange. It can have match statements, which are used as selection criteria to select a policy during negotiation.

See the "IKEv2 Smart Defaults" section for information about the default IKEv2 policy. See the "Configuring Advanced IKEv2 CLI Constructs" section for information about how to override the default IKEv2 policy and to define new policies.

IKEv2 Profile

An IKEv2 profile is a repository of nonnegotiable parameters of the IKE SA, such as local or remote identities and authentication methods and services that are available to authenticated peers that match the profile. An IKEv2 profile must be attached to either a crypto map or an IPSec profile on the initiator. An IKEv2 profile is not mandatory on the responder.

IKEv2 Key Ring

An IKEv2 key ring is a repository of symmetric and asymmetric preshared keys and is independent of the IKEv1 key ring. The IKEv2 key ring is associated with an IKEv2 profile and hence supports a set of peers that match the IKEv2 profile. The IKEv2 key ring gets its VPN routing and forwarding (VRF) context from the associated IKEv2 profile.

IKEv2 Smart Defaults

The IKEv2 Smart Defaults feature minimizes the FlexVPN configuration by covering most of the use cases. IKEv2 smart defaults can be customized for specific use cases, though this is not recommended.

See the "Configuring Advanced IKEv2 CLI Constructs" section for information about how to modify the default IKEv2 constructs.

The following rules apply to the IKEv2 Smart Defaults feature:

  1. A default configuration is displayed in the corresponding show command with default as a keyword and with no argument. For example, the show crypto ikev2 proposal default command displays the default IKEv2 proposal and the show crypto ikev2 proposal command displays the default IKEv2 proposal, along with any user-configured proposals.
  2. A default configuration is displayed in the show running-config all command; it is not displayed in the show running-config command.
  3. You can modify the default configuration, which is displayed in the show running-config all command.
  4. A default configuration can be disabled using the no form of the command; for example, no crypto ikev2 proposal default. A disabled default configuration is not used in negotiation but the configuration is displayed in the show running-config command. A disabled default configuration loses any user modification and restores system-configured values.
  5. A default configuration can be reenabled using the default form of the command, which restores system-configured values; for example, default crypto ikev2 proposal.
  6. The default mode for the default transform set is transport; the default mode for all other transform sets is tunnel.

Note


Cisco no longer recommends using MD5 (including HMAC variant) and Diffie-Hellman (DH) groups 1, 2 and 5; instead, you should use SHA-256 and DH Groups 14 or higher. For more information about the latest Cisco cryptographic recommendations, see the Next Generation Encryption (NGE) white paper.

The following table lists the commands that are enabled with the IKEv2 Smart Defaults feature, along with the default values.

Table 1 IKEv2 Command Defaults

Command Name

Default Values

crypto ikev2 authorization policy

Device# show crypto ikev2 authorization policy default

IKEv2 Authorization policy: default
route set interface
route accept any tag: 1 distance: 2

crypto ikev2 proposal

Device# show crypto ikev2 proposal default
 
IKEv2 proposal: default 
Encryption: AES-CBC-256 AES-CBC-192 AES-CBC-128
Integrity: SHA512 SHA384 SHA256 SHA96 MD596
PRF: SHA512 SHA384 SHA256 SHA1 MD5
DH Group: DH_GROUP_1536_MODP/Group 5 DH_GROUP_1024_MODP/Group 2.

crypto ikev2 policy

Device# show crypto ikev2 policy default

IKEv2 policy: default
Match fvrf: any
Match address local: any 
Proposal: default

crypto ipsec profile

Device# show crypto ipsec profile default

IPSEC profile default
Security association lifetime: 4608000 kilobytes/3600 seconds
Responder-Only (Y/N): N
PFS (Y/N): N
Transform sets={
default: { esp-aes esp-sha-hmac },
}

crypto ipsec transform-set

Device# show crypto ipsec transform-set default

Transform set default: { esp-aes esp-sha-hmac }
will negotiate = { Tunnel, },

Note


Before you can use the default IPsec profile, explicitly specify the crypto ipsec profile command on a tunnel interface using the tunnel protection ipsec profile default command.

IKEv2 Suite-B Support

Suite-B is a set of cryptographic algorithms promulgated by the National Security Agency as part of its Cryptographic Modernization Program. Suite-B for Internet Key Exchange (IKE) and IPsec is defined in RFC 4869. The Suite-B components are as follows:

  • Advanced Encryption Standard (AES) 128- and 256-bit keys configured in the IKEv2 proposal. For data traffic, AES should be used in Galois Counter Mode (GCM) that is configured in the IPsec transform set.
  • Elliptic Curve Digital Signature Algorithm (ECDSA) configured in the IKEv2 profile.
  • Secure Hashing Algorithm 2 (SHA-256 and SHA-384) configured in the IKEv2 proposal and IPsec transform set.

Suite-B requirements comprise four user-interface suites of cryptographic algorithms for use with IKE and IPsec. Each suite consists of an encryption algorithm, a digital-signature algorithm, a key-agreement algorithm, and a hash- or message-digest algorithm. See the "Configuring Security for VPNs with IPsec" feature module for detailed information about Cisco Suite-B support.

How to Configure Internet Key Exchange Version 2

Configuring Basic Internet Key Exchange Version 2 CLI Constructs

To enable IKEv2 on a crypto interface, attach an Internet Key Exchange Version 2 (IKEv2) profile to the crypto map or IPsec profile applied to the interface. This step is optional on the IKEv2 responder.


Note


The difference between IKEv1 and IKEv2 is that you need not enable IKEv1 on individual interfaces because IKEv1 is enabled globally on all interfaces on a device.

Perform the following tasks to manually configure basic IKEv2 constructs:

Configuring the IKEv2 Key Ring

Perform this task to configure the IKEv2 key ring if the local or remote authentication method is a preshared key.

IKEv2 key ring keys must be configured in the peer configuration submode that defines a peer subblock. An IKEv2 key ring can have multiple peer subblocks. A peer subblock contains a single symmetric or asymmetric key pair for a peer or peer group identified by any combination of the hostname, identity, and IP address.

IKEv2 key rings are independent of IKEv1 key rings. The key differences are as follows:

  • IKEv2 key rings support symmetric and asymmetric preshared keys.
  • IKEv2 key rings do not support Rivest, Shamir, and Adleman (RSA) public keys.
  • IKEv2 key rings are specified in the IKEv2 profile and are not looked up, unlike IKEv1, where keys are looked up on receipt of MM1 to negotiate the preshared key authentication method. The authentication method is not negotiated in IKEv2.
  • IKEv2 key rings are not associated with VPN routing and forwarding (VRF) during configuration. The VRF of an IKEv2 key ring is the VRF of the IKEv2 profile that refers to the key ring.
  • A single key ring can be specified in an IKEv2 profile, unlike an IKEv1 profile, which can specify multiple key rings.
  • A single key ring can be specified in more than one IKEv2 profile, if the same keys are shared across peers matching different profiles.
  • An IKEv2 key ring is structured as one or more peer subblocks.

On an IKEv2 initiator, the IKEv2 key ring key lookup is performed using the peer's hostname or the address, in that order. On an IKEv2 responder, the key lookup is performed using the peer's IKEv2 identity or the address, in that order.


Note


You cannot configure the same identity in more than one peer.
SUMMARY STEPS

1.    enable

2.    configure terminal

3.    crypto ikev2 keyring keyring-name

4.    peer name

5.    description line-of-description

6.    hostname name

7.    address {ipv4-address [mask] | ipv6-address prefix}

8.    identity {address {ipv4-address | ipv6-address} | fqdn name | email email-id | key-id key-id}

9.    pre-shared-key {local | remote} [0 | 6] line hex hexadecimal-string

10.    end


DETAILED STEPS
  Command or Action Purpose
Step 1
enable


Example:

Device> enable

 

Enables privileged EXEC mode.

  • Enter your password if prompted.
 
Step 2
configure terminal


Example:

Device# configure terminal

 

Enters global configuration mode.

 
Step 3
crypto ikev2 keyring keyring-name


Example:

Device(config)# crypto ikev2 keyring kyr1

 

Defines an IKEv2 key ring and enters IKEv2 key ring configuration mode.

 
Step 4
peer name


Example:

Device(config-ikev2-keyring)# peer peer1

 

Defines the peer or peer group and enters IKEv2 key ring peer configuration mode.

 
Step 5
description line-of-description


Example:

Device(config-ikev2-keyring-peer)# description this is the first peer

 

(Optional) Describes the peer or peer group.

 
Step 6
hostname name


Example:

Device(config-ikev2-keyring-peer)# hostname host1

 

Specifies the peer using a hostname.

 
Step 7
address {ipv4-address [mask] | ipv6-address prefix}


Example:

Device(config-ikev2-keyring-peer)# address 10.0.0.1 255.255.255.0

 

Specifies an IPv4 or IPv6 address or range for the peer.

Note    This IP address is the IKE endpoint address and is independent of the identity address.
 
Step 8
identity {address {ipv4-address | ipv6-address} | fqdn name | email email-id | key-id key-id}


Example:

Device(config-ikev2-keyring-peer)# identity address 10.0.0.5

 

Identifies the IKEv2 peer through the following identities:

  • E-mail
  • Fully qualified domain name (FQDN)
  • IPv4 or IPv6 address
  • Key ID
Note    The identity is available for key lookup on the IKEv2 responder only.
 
Step 9
pre-shared-key {local | remote} [0 | 6] line hex hexadecimal-string


Example:

Device(config-ikev2-keyring-peer)# pre-shared-key local key1

 

Specifies the preshared key for the peer.

 
Step 10
end


Example:

Device(config-ikev2-keyring-peer)# end

 

Exits IKEv2 key ring peer configuration mode and returns to privileged EXEC mode.

 
What to Do Next

After configuring the IKEv2 key ring, configure the IKEv2 profile. For more information, see the "Configuring IKEv2 Profile (Basic)" section.

Configuring an IKEv2 Profile (Basic)

Perform this task to configure the mandatory commands for an IKEv2 profile.

An IKEv2 profile is a repository of nonnegotiable parameters of the IKE security association (SA) (such as local or remote identities and authentication methods) and services available to authenticated peers that match the profile. An IKEv2 profile must be configured and associated with either a crypto map or an IPsec profile on the IKEv2 initiator. Use the set ikev2-profile profile-name command to associate a profile with a crypto map or an IPsec profile. To disassociate the profile, use the no form of the command.

The following rules apply to match statements:

  • An IKEv2 profile must contain a match identity or a match certificate statement; otherwise, the profile is considered incomplete and is not used. An IKEv2 profile can have more than one match identity or match certificate statements.
  • An IKEv2 profile must have a single match Front Door VPN routing and forwarding (FVRF) statement.
  • When a profile is selected, multiple match statements of the same type are logically ORed, and multiple match statements of different types are logically ANDed.
  • The match identity and match certificate statements are considered to be the same type of statements and are ORed.
  • Configuration of overlapping profiles is considered a misconfiguration. In the case of multiple profile matches, no profile is selected.

Use the show crypto ikev2 profile profile-name command to display the IKEv2 profile.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    crypto ikev2 profile profile-name

4.    description line-of-description

5.    aaa accounting {psk | cert | eap} list-name

6.    authentication {local {rsa-sig | pre-share | ecdsa-sig | eap} | remote {eap [query-identity | timeout seconds] | rsa-sig | pre-share | ecdsa-sig}}

7.    dpd interval retry-interval {on-demand | periodic}

8.    identity local {address {ipv4-address | ipv6-address} | dn | email email-string | fqdn fqdn-string | key-id opaque-string}

9.   initial-contact [force]

10.    ivrf name

11.    keyring {local keyring-name | aaa list-name name-mangler mangler-name}

12.    lifetime seconds

13.    match {address local {ipv4-address | ipv6-address | interface name} | certificate certificate-map | fvrf {fvrf-name | any} | identity remote {address {ipv4-address [mask] | ipv6-address prefix} | {email | fqdn} [domain] string | key-id opaque-string}}

14.    nat keepalive seconds

15.    pki trustpoint trustpoint-label [sign | verify]

16.    virtual-template number

17.    end


DETAILED STEPS
  Command or Action Purpose
Step 1
enable


Example:

Device> enable

 

Enables privileged EXEC mode.

  • Enter your password if prompted.
 
Step 2
configure terminal


Example:

Device# configure terminal

 

Enters global configuration mode.

 
Step 3
crypto ikev2 profile profile-name


Example:

Device(config)# crypto ikev2 profile profile1

 

Defines an IKEv2 profile and enters IKEv2 profile configuration mode.

 
Step 4
description line-of-description


Example:

Device(config-ikev2-profile)# description This is an IKEv2 profile

 

(Optional) Describes the profile.

 
Step 5
aaa accounting {psk | cert | eap} list-name


Example:

Device(config-ikev2-profile)# aaa accounting eap list1

 

(Optional) Enables authentication, authorization, and accounting (AAA) accounting method lists for IPsec sessions.

Note    If the psk, cert, or eap keyword is not specified, the AAA accounting method list is used irrespective of the peer authentication method.
 
Step 6
authentication {local {rsa-sig | pre-share | ecdsa-sig | eap} | remote {eap [query-identity | timeout seconds] | rsa-sig | pre-share | ecdsa-sig}}


Example:

Device(config-ikev2-profile)# authentication local ecdsa-sig

 

Specifies the local or remote authentication method.

Note    You can specify only one local authentication method but multiple remote authentication methods.
 
Step 7
dpd interval retry-interval {on-demand | periodic}


Example:

Device(config-ikev2-profile)# dpd 1000 250 periodic

 

(Optional) Configures Dead Peer Detection (DPD) globally for peers matching the profile.

Note    DPD is disabled by default.
 
Step 8
identity local {address {ipv4-address | ipv6-address} | dn | email email-string | fqdn fqdn-string | key-id opaque-string}


Example:

Device(config-ikev2-profile)# identity local email abc@example.com

 

(Optional) Specifies the local IKEv2 identity type.

Note    If the local authentication method is a preshared key, the default local identity is the IP address. If the local authentication method is a Rivest, Shamir, and Adleman (RSA) signature, the default local identity is a Distinguished Name.
 
Step 9
initial-contact [force]


Example:

Device(config-ikev2-profile)# initial-contact force

 

Enforces initial contact processing if the initial contact notification is not received in the IKE_AUTH exchange.

 
Step 10
ivrf name


Example:

Device(config-ikev2-profile)# ivrf vrf1

 

(Optional) Specifies a user-defined VPN routing and forwarding (VRF) or global VRF if the IKEv2 profile is attached to a crypto map.

  • If the IKEv2 profile is used for tunnel protection, the Inside VRF (IVRF) for the tunnel interface should be configured on the tunnel interface.
Note    IVRF specifies the VRF for cleartext packets. The default value for IVRF is FVRF.
 
Step 11
keyring {local keyring-name | aaa list-name name-mangler mangler-name}


Example:

Device(config-ikev2-profile)# keyring aaa keyring1 name-mangler mangler1

 

Specifies the local or AAA-based key ring that must be used with the local and remote preshared key authentication method.

Note    You can specify only one key ring. Local AAA is not supported for AAA-based preshared keys.
Note    Depending on your release, the local keyword and the name-mangler mangler-name keyword-argument pair should be used.
 
Step 12
lifetime seconds


Example:

Device(config-ikev2-profile)# lifetime 1000

 

Specifies the lifetime, in seconds, for the IKEv2 SA.

 
Step 13
match {address local {ipv4-address | ipv6-address | interface name} | certificate certificate-map | fvrf {fvrf-name | any} | identity remote {address {ipv4-address [mask] | ipv6-address prefix} | {email | fqdn} [domain] string | key-id opaque-string}}


Example:

Device(config-ikev2-profile)# match address local interface Ethernet 2/0

 

Uses match statements to select an IKEv2 profile for a peer.

 
Step 14
nat keepalive seconds


Example:

Device(config-ikev2-profile)# nat keepalive 500

 

(Optional) Enables NAT keepalive and specifies the duration in seconds.

  • NAT is disabled by default.
 
Step 15
pki trustpoint trustpoint-label [sign | verify]


Example:

Device(config-ikev2-profile)# pki trustpoint tsp1 sign

 

Specifies Public Key Infrastructure (PKI) trustpoints for use with the RSA signature authentication method.

Note    If the sign or verify keyword is not specified, the trustpoint is used for signing and verification.
Note    In contrast to IKEv1, a trustpoint must be configured in an IKEv2 profile for certificate-based authentication to succeed. There is no fallback for globally configured trustpoints if this command is not present in the configuration. The trustpoint configuration applies to the IKEv2 initiator and responder.
 
Step 16
virtual-template number


Example:

Device(config-ikev2-profile)# virtual-template 125

 

(Optional) Specifies the virtual template for cloning a virtual access interface (VAI).

Note    For the IPsec Dynamic Virtual Tunnel Interface (DVTI), a virtual template must be specified in an IKEv2 profile, without which an IKEv2 session is not initiated.
 
Step 17
end


Example:

Device(config-ikev2-profile)# end

 

Exits IKEv2 profile configuration mode and returns to privileged EXEC mode.

 

Configuring Advanced Internet Key Exchange Version 2 CLI Constructs

This section describes the global IKEv2 CLI constructs and how to override the IKEv2 default CLI constructs. IKEv2 smart defaults support most use cases and hence, we recommend that you override the defaults only if they are required for specific use cases not covered by the defaults.

Perform the following tasks to configure advanced IKEv2 CLI constructs:

Configuring Global IKEv2 Options

Perform this task to configure global IKEv2 options that are independent of peers.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    crypto ikev2 certificate-cache number-of-certificates

4.    crypto ikev2 cookie-challenge number

5.    crypto ikev2 diagnose error number

6.    crypto ikev2 dpd interval retry-interval {on-demand | periodic}

7.    crypto ikev2 http-url cert

8.    crypto ikev2 limit {max-in-negotiation-sa limit | max-sa limit}

9.    crypto ikev2 nat keepalive interval

10.    crypto ikev2 window size

11.    crypto logging ikev2

12.    end


DETAILED STEPS
  Command or Action Purpose
Step 1
enable


Example:

Device> enable

 

Enables privileged EXEC mode.

  • Enter your password if prompted.
 
Step 2
configure terminal


Example:

Device# configure terminal

 

Enters global configuration mode.

 
Step 3
crypto ikev2 certificate-cache number-of-certificates


Example:

Device(config)# crypto ikev2 certificate-cache 750

 

Defines the cache size for storing certificates fetched from HTTP URLs.

 
Step 4
crypto ikev2 cookie-challenge number


Example:

Device(config)# crypto ikev2 cookie-challenge 450

 

Enables an IKEv2 cookie challenge only when the number of half-open security associations (SAs) exceeds the configured number.

  • Cookie challenge is disabled by default.
 
Step 5
crypto ikev2 diagnose error number


Example:

Device(config)# crypto ikev2 diagnose error 500

 

Enables IKEv2 error diagnostics and defines the number of entries in the exit path database.

  • IKEv2 error diagnostics is disabled by default.
 
Step 6
crypto ikev2 dpd interval retry-interval {on-demand | periodic}


Example:

Device(config)# crypto ikev2 dpd 500 50 on-demand

 

Allows live checks for peers as follows:

  • Dead Peer Detection (DPD) is disabled by default.
 
Step 7
crypto ikev2 http-url cert


Example:

Device(config)# crypto ikev2 http-url cert

 

Enables the HTTP CERT support.

  • HTTP CERT is disabled by default.
 
Step 8
crypto ikev2 limit {max-in-negotiation-sa limit | max-sa limit}


Example:

Device(config)# crypto ikev2 limit max-in-negotiation-sa 5000

 

Enables connection admission control (CAC).

  • Connection admission control is disabled by default.
 
Step 9
crypto ikev2 nat keepalive interval


Example:

Device(config)# crypto ikev2 nat keepalive 500

 

Enables the Network Address Translation (NAT) keepalive that prevents the deletion of NAT entries in the absence of any traffic when there is NAT between Internet Key Exchange (IKE) peers.

  • NAT keepalive is disabled by default.
 
Step 10
crypto ikev2 window size


Example:

Device(config)# crypto ikev2 window 15

 

Allows multiple IKEv2 request-response pairs in transit.

  • The default window size is 5.

 
Step 11
crypto logging ikev2


Example:

Device(config)# crypto logging ikev2

 

Enables IKEv2 syslog messages.

  • IKEv2 syslog messages are disabled by default.
 
Step 12
end


Example:

Device(config)# end

 

Exits global configuration mode and returns to privileged EXEC mode.

 

Configuring IKEv2 Proposal

Refer to the "IKEv2 Smart Defaults" section for information on the default IKEv2 proposal.

Perform this task to override the default IKEv2 proposal or to manually configure the proposals if you do not want to use the default proposal.

An IKEv2 proposal is a set of transforms used in the negotiation of IKEv2 SA as part of the IKE_SA_INIT exchange. An IKEv2 proposal is regarded as complete only when it has at least an encryption algorithm, an integrity algorithm, and a Diffie-Hellman (DH) group configured. If no proposal is configured and attached to an IKEv2 policy, the default proposal in the default IKEv2 policy is used in negotiation.


Note


Security threats, as well as the cryptographic technologies to help protect against them, are constantly changing. For more information about the latest Cisco cryptographic recommendations, see the Next Generation Encryption (NGE) white paper.

Although the IKEv2 proposal is similar to the crypto isakmp policy command, the IKEv2 proposal differs as follows:

  • An IKEv2 proposal allows configuring one or more transforms for each transform type.
  • An IKEv2 proposal does not have any associated priority.
SUMMARY STEPS

1.    enable

2.    configure terminal

3.    crypto ikev2 proposal name

4.    encryption {3des} {aes-cbc-128} {aes-cbc-192} {aes-cbc-256}

5.    integrity {md5} {sha1} {sha256} {sha384} {sha512}

6.    group {1} {14} {15} {16} {19} {2} {20} {24} {5}

7.    end

8.    show crypto ikev2 proposal [name | default]


DETAILED STEPS
  Command or Action Purpose
Step 1
enable


Example:

Device> enable

 

Enables privileged EXEC mode.

  • Enter your password if prompted.
 
Step 2
configure terminal


Example:

Device# configure terminal

 

Enters global configuration mode.

 
Step 3
crypto ikev2 proposal name


Example:

Device(config)# crypto ikev2 proposal proposal1

 

Overrides the default IKEv2 proposal, defines an IKEv2 proposal name, and enters IKEv2 proposal configuration mode.

 
Step 4
encryption {3des} {aes-cbc-128} {aes-cbc-192} {aes-cbc-256}


Example:

Device(config-ikev2-proposal)# encryption aes-cbc-128 aes-cbc-192

 

Specifies one or more transforms of the encryption type, which are as follows:

  • 3des (No longer recommended)
  • aes-cbc-128
  • aes-cbc-192
  • aes-cbc-256
 
Step 5
integrity {md5} {sha1} {sha256} {sha384} {sha512}


Example:

Device(config-ikev2-proposal)# integrity sha1

 

Specifies one or more transforms of the integrity algorithm type, which are as follows:

  • The md5 keyword specifies MD5 (HMAC variant) as the hash algorithm. (No longer recommended)
  • The sha1 keyword specifies SHA-1 (HMAC variant) as the hash algorithm.
  • The sha256 keyword specifies SHA-2 family 256-bit (HMAC variant) as the hash algorithm.
  • The sha384 keyword specifies SHA-2 family 384-bit (HMAC variant) as the hash algorithm.
  • The sha512 keyword specifies SHA-2 family 512-bit (HMAC variant) as the hash algorithm.
 
Step 6
group {1} {14} {15} {16} {19} {2} {20} {24} {5}


Example:

Device(config-ikev2-proposal)# group 14

 

Specifies the Diffie-Hellman (DH) group identifier.

  • The default DH group identifiers are group 2 and 5 in the IKEv2 proposal.
    • 1--768-bit DH (No longer recommended).
    • 2--1024-bit DH (No longer recommended).
    • 5--1536-bit DH (No longer recommended).
    • 14--Specifies the 2048-bit DH group.
    • 15--Specifies the 3072-bit DH group.
    • 16--Specifies the 4096-bit DH group.
    • 19--Specifies the 256-bit elliptic curve DH (ECDH) group.
    • 20--Specifies the 384-bit ECDH group.
    • 24--Specifies the 2048-bit DH group.

The group chosen must be strong enough (have enough bits) to protect the IPsec keys during negotiation. A generally accepted guideline recommends the use of a 2048-bit group after 2013 (until 2030). Either group 14 or group 24 can be selected to meet this guideline. Even if a longer-lived security method is needed, the use of Elliptic Curve Cryptography is recommended, but group 15 and group 16 can also be considered.

 
Step 7
end


Example:

Device(config-ikev2-proposal)# end

 

Exits IKEv2 proposal configuration mode and returns to privileged EXEC mode.

 
Step 8
show crypto ikev2 proposal [name | default]


Example:

Device# show crypto ikev2 proposal default

 

(Optional) Displays the IKEv2 proposal.

 
What to Do Next

After you create the IKEv2 proposal, attach it to a policy so that the proposal is picked for negotiation. For information about completing this task, see the "Configuring IKEv2 Policy" section.

Configuring IKEv2 Policies

See the "IKEv2 Smart Defaults" section for information about the default IKEv2 policy.

Perform this task to override the default IKEv2 policy or to manually configure the policies if you do not want to use the default policy.

An IKEv2 policy must contain at least one proposal to be considered as complete and can have match statements, which are used as selection criteria to select a policy for negotiation. During the initial exchange, the local address (IPv4 or IPv6) and the Front Door VRF (FVRF) of the negotiating SA are matched with the policy and the proposal is selected.

The following rules apply to the match statements:

  • An IKEv2 policy without any match statements will match all peers in the global FVRF.
  • An IKEv2 policy can have only one match FVRF statement.
  • An IKEv2 policy can have one or more match address local statements.
  • When a policy is selected, multiple match statements of the same type are logically ORed and match statements of different types are logically ANDed.
  • There is no precedence between match statements of different types.
  • Configuration of overlapping policies is considered a misconfiguration. In the case of multiple, possible policy matches, the first policy is selected.
SUMMARY STEPS

1.    enable

2.    configure terminal

3.    crypto ikev2 policy name

4.    proposal name

5.    match fvrf {fvrf-name | any}

6.    match address local {ipv4-address | ipv6-address}

7.    end

8.    show crypto ikev2 policy [policy-name | default]


DETAILED STEPS
  Command or Action Purpose
Step 1
enable


Example:

Device> enable

 

Enables privileged EXEC mode.

  • Enter your password if prompted.
 
Step 2
configure terminal


Example:

Device# configure terminal

 

Enters global configuration mode.

 
Step 3
crypto ikev2 policy name


Example:

Device(config)# crypto ikev2 policy policy1

 

Overrides the default IKEv2 policy, defines an IKEv2 policy name, and enters IKEv2 policy configuration mode.

 
Step 4
proposal name


Example:

Device(config-ikev2-policy)# proposal proposal1

 

Specifies the proposals that must be used with the policy.

  • The proposals are prioritized in the order of listing.
Note    You must specify at least one proposal. You can specify additional proposals with each proposal in a separate statement.
 
Step 5
match fvrf {fvrf-name | any}


Example:

Device(config-ikev2-policy)# match fvrf any

 

(Optional) Matches the policy based on a user-configured FVRF or any FVRF.

  • The default is global FVRF.
Note    The match fvrf any command must be explicitly configured in order to match any VRF. The FVRF specifies the VRF in which the IKEv2 packets are negotiated.
 
Step 6
match address local {ipv4-address | ipv6-address}


Example:

Device(config-ikev2-policy)# match address local 10.0.0.1

 

(Optional) Matches the policy based on the local IPv4 or IPv6 address.

  • The default matches all the addresses in the configured FVRF.
 
Step 7
end


Example:

Device(config-ikev2-policy)# end

 

Exits IKEv2 policy configuration mode and returns to privileged EXEC mode.

 
Step 8
show crypto ikev2 policy [policy-name | default]


Example:

Device# show crypto ikev2 policy policy1

 

(Optional) Displays the IKEv2 policy.

 

Configuration Examples for Internet Key Exchange Version 2

Configuration Examples for Basic Internet Key Exchange Version 2 CLI Constructs

Example: Configuring the IKEv2 Key Ring

Example: IKEv2 Key Ring with Multiple Peer Subblocks

The following example shows how to configure an Internet Key Exchange Version 2 (IKEv2) key ring with multiple peer subblocks:

crypto ikev2 keyring keyring-1
 peer peer1
  description peer1 
  address 209.165.200.225 255.255.255.224
  pre-shared-key key-1
 peer peer2
  description peer2
  hostname peer1.example.com
  pre-shared-key key-2
 peer peer3
  description peer3
  hostname peer3.example.com
  identity key-id abc
  address 209.165.200.228 255.255.255.224
  pre-shared-key key-3
Example: IKEv2 Keyring with Symmetric Preshared Keys Based on an IP Address

The following example shows how to configure an IKEv2 key ring with symmetric preshared keys based on an IP address. The following is the initiator's key ring:

crypto ikev2 keyring keyring-1
 peer peer1
  description peer1
  address 209.165.200.225 255.255.255.224
  pre-shared-key key1

The following is the responder's key ring:

crypto ikev2 keyring keyring-1
 peer peer2
  description peer2 
  address 209.165.200.228 255.255.255.224
  pre-shared-key key1
Example: IKEv2 Key Ring with Asymmetric Preshared Keys Based on an IP Address

The following example shows how to configure an IKEv2 key ring with asymmetric preshared keys based on an IP address. The following is the initiator's key ring:

crypto ikev2 keyring keyring-1
 peer peer1
  description peer1 with asymmetric keys
  address 209.165.200.225 255.255.255.224
  pre-shared-key local key1
  pre-shared-key remote key2

The following is the responder's key ring:

crypto ikev2 keyring keyring-1
 peer peer2
  description peer2 with asymmetric keys
  address 209.165.200.228 255.255.255.224
  pre-shared-key local key2
  pre-shared-key remote key1
Example: IKEv2 Key Ring with Asymmetric Preshared Keys Based on a Hostname

The following example shows how to configure an IKEv2 key ring with asymmetric preshared keys based on the hostname. The following is the initiator's key ring:

crypto ikev2 keyring keyring-1
 peer host1
  description host1 in example domain
  hostname host1.example.com
  pre-shared-key local key1
  pre-shared-key remote key2

The following is the responder's keyring:

crypto ikev2 keyring keyring-1
 peer host2
  description host2 in abc domain
  hostname host2.example.com
  pre-shared-key local key2
  pre-shared-key remote key1
Example: IKEv2 Key Ring with Symmetric Preshared Keys Based on an Identity

The following example shows how to configure an IKEv2 key ring with symmetric preshared keys based on an identity:

crypto ikev2 keyring keyring-4
 peer abc
  description example domain
  identity fqdn example.com
  pre-shared-key abc-key-1
 peer user1
  description user1 in example domain
  identity email user1@example.com
  pre-shared-key abc-key-2
 peer user1-remote
  description user1 example remote users
  identity key-id example
  pre-shared-key example-key-3
Example: IKEv2 Key Ring with a Wildcard Key

The following example shows how to configure an IKEv2 key ring with a wildcard key:

crypto ikev2 keyring keyring-1
 peer cisco
  description example domain
  address 0.0.0.0 0.0.0.0 
  pre-shared-key example-key
Example: Matching a Key Ring

The following example shows how a key ring is matched:

crypto ikev2 keyring keyring-1
 peer cisco
  description example.com
  address 0.0.0.0 0.0.0.0 
  pre-shared-key xyz-key
 peer peer1
  description abc.example.com
  address 10.0.0.0 255.255.0.0 
  pre-shared-key abc-key
 peer host1
  description host1@abc.example.com
  address 10.0.0.1
  pre-shared-key host1-example-key

In the example shown, the key lookup for peer 10.0.0.1 first matches the wildcard key example-key, then the prefix key example-key, and finally the host key host1-example-key. The best match host1-example-key is used.

crypto ikev2 keyring keyring-2
 peer host1
 description host1 in abc.example.com sub-domain
 address 10.0.0.1
 pre-shared-key host1-example-key
 peer host2
  description example domain
  address 0.0.0.0 0.0.0.0 
  pre-shared-key example-key

In the example shown, the key lookup for peer 10.0.0.1 would first match the host key host1-abc-key. Because this is a specific match, no further lookup is performed.

Example: Configuring the Profile

Example: IKEv2 Profile Matched on Remote Identity

The following profile supports peers that identify themselves using fully qualified domain name (FQDN) example.com and authenticate with the RSA signature using trustpoint-remote. The local node authenticates itself with a preshared key using keyring-1.

crypto ikev2 profile profile2
 match identity remote fqdn example.com
 identity local email router2@example.com
 authentication local pre-share
 authentication remote rsa-sig
 keyring keyring-1
 pki trustpoint trustpoint-remote verify
 lifetime 300
 dpd 5 10 on-demand
 virtual-template 1
Example: IKEv2 Profile Supporting Two Peers

The following example shows how to configure an IKEv2 profile supporting two peers that use different authentication methods:

crypto ikev2 profile profile2
 match identity remote email user1@example.com
 match identity remote email user2@example.com
 identity local email router2@cisco.com
 authentication local rsa-sig
 authentication remote pre-share
 authentication remote rsa-sig
 keyring keyring-1
 pki trustpoint trustpoint-local sign
 pki trustpoint trustpoint-remote verify
 lifetime 300
 dpd 5 10 on-demand
 virtual-template 1

Example: Configuring FlexVPN Site-to-Site with Dynamic Routing Using Certificates and IKEv2 Smart Defaults

The following examples show a site-to-site connection between a branch device (initiator, using a static virtual tunnel interface [sVTI]) and a central device (responder, using a dynamic virtual tunnel interface [dVTI]) with dynamic routing over the tunnel. The example uses IKEv2 smart defaults, and the authentication is performed using certificates (RSA signatures).


Note


A RSA modulus size of 2048 is recommended.

The peers use the FQDN as their IKEv2 identity, and the IKEv2 profile on the responder matches the domain in the identity FQDN.

The configuration on the initiator (branch device) is as follows:

hostname branch
ip domain name cisco.com
!
crypto ikev2 profile branch-to-central
 match identity remote fqdn central.cisco.com
 identity local fqdn branch.cisco.com
 authentication local rsa-sig
 authentication remote rsa-sig
 pki trustpoint CA
!
crypto ipsec profile svti
 set ikev2-profile branch-to-central
!
interface Tunnel0
 ip address 172.16.0.101 255.255.255.0
 tunnel source Ethernet0/0
 tunnel mode ipsec ipv4
 tunnel destination 10.0.0.100
 tunnel protection ipsec profile svti
!
interface Ethernet0/0
 ip address 10.0.0.101 255.255.255.0
!
interface Ethernet1/0
 ip address 192.168.101.1 255.255.255.0
!
router rip
 version 2
 passive-interface Ethernet1/0
 network 172.16.0.0
 network 192.168.101.0
 no auto-summary

The configuration on the responder (central router) is as follows:

hostname central
ip domain name cisco.com
!
crypto ikev2 profile central-to-branch
 match identity remote fqdn domain cisco.com
 identity local fqdn central.cisco.com
 authentication local rsa-sig
 authentication remote rsa-sig
 pki trustpoint CA
 virtual-template 1
!
interface Loopback0
 ip address 172.16.0.100 255.255.255.0
!
interface Ethernet0/0
 ip address 10.0.0.100 255.255.255.0
!
interface Ethernet1/0
 ip address 192.168.100.1 255.255.255.0
!
interface Virtual-Template1 type tunnel
 ip unnumbered Loopback0
 tunnel source Ethernet0/0
 tunnel mode ipsec ipv4
 tunnel protection ipsec profile default
!
router rip
 version 2
 passive-interface Ethernet1/0
 network 172.16.0.0
 network 192.168.100.0
 no auto-summary

Configuration Examples for Advanced Internet Key Exchange Version 2 CLI Constructs

Example: Configuring the Proposal

Example: IKEv2 Proposal with One Transform for Each Transform Type

This example shows how to configure an IKEv2 proposal with one transform for each transform type:

crypto ikev2 proposal proposal-1
 encryption aes-cbc-128
 integrity sha1
 group 14
Example: IKEv2 Proposal with Multiple Transforms for Each Transform Type

This example shows how to configure an IKEv2 proposal with multiple transforms for each transform type:

crypto ikev2 proposal proposal-2
 encryption aes-cbc-128 aes-cbc-192
 integrity sha1
 group 14

Note


Cisco no longer recommends using 3DES, MD5 (including HMAC variant), and Diffie-Hellman(DH) groups 1, 2 and 5; instead, you should use AES, SHA-256 and DH Groups 14 or higher. For more information about the latest Cisco cryptographic recommendations, see the Next Generation Encryption (NGE) white paper.

The IKEv2 proposal proposal-2 shown translates to the following prioritized list of transform combinations:

  • aes-cbc-128, sha1, 14
  • aes-cbc-192, sha1, 14
Example: IKEv2 Proposals on the Initiator and Responder

The following example shows how to configure IKEv2 proposals on the initiator and the responder. The proposal on the initiator is as follows:

crypto ikev2 proposal proposal-1
 encryption aes-cbc-192 aes-cbc-128
 integrity sha-256 sha1
 group 14 24

The proposal on the responder is as follows:

crypto ikev2 proposal proposal-2
 encryption aes-cbc-128 aes-cbc-192
 peer
 integrity sha1 sha-256 
 group 24 14

The selected proposal will be as follows:

encryption aes-cbc-128
integrity sha1 
group 14

In the proposals shown for the initiator and responder, the initiator and responder have conflicting preferences. In this case, the initiator is preferred over the responder.

Example: Configuring the Policy

Example: IKEv2 Policy Matched on a VRF and Local Address

The following example shows how an IKEv2 policy is matched based on a VRF and local address:

crypto ikev2 policy policy2
 match vrf vrf1
 match local address 10.0.0.1
 proposal proposal-1
Example: IKEv2 Policy with Multiple Proposals That Match All Peers in a Global VRF

The following example shows how an IKEv2 policy with multiple proposals matches the peers in a global VRF:

crypto ikev2 policy policy2
 proposal proposal-A
 proposal proposal-B
 proposal proposal-B
Example: IKEv2 Policy That Matches All Peers in Any VRF

The following example shows how an IKEv2 policy matches the peers in any VRF:

crypto ikev2 policy policy2
 match vrf any
 proposal proposal-1
Example: Matching a Policy

Do not configure overlapping policies. If there are multiple possible policy matches, the best match is used, as shown in the following example:

crypto ikev2 policy policy1
 match fvrf fvrf1
crypto ikev2 policy policy2
 match fvrf fvff1
 match local address 10.0.0.1

The proposal with FVRF as fvrf1 and the local peer as 10.0.0.1 matches policy1 and policy2, but policy2 is selected because it is the best match.

Where to Go Next

After configuring IKEv2, proceed to configure IPsec VPNs. For more information, see the "Configuring Security for VPNs with IPsec" module.

Additional References

Related Documents

Related Topic

Document Title

Cisco IOS commands

Cisco IOS Master Command List, All Releases

Security commands

IPsec configuration

Configuring Security for VPNs with IPsec

Suite-B ESP transforms

Configuring Security for VPNs with IPsec

Suite-B SHA-2 family (HMAC variant) and elliptic curve (EC) key pair configuration

Configuring Internet Key Exchange for IPsec VPNs

Suite-B elliptic curve Diffie-Hellman (ECDH) support for IPsec SA negotiation

Configuring Internet Key Exchange for IPsec VPNs

Suite-B support for certificate enrollment for a PKI

Configuring Certificate Enrollment for a PKI

Supported standards for use with IKE

Internet Key Exchange for IPsec VPNs Configuration Guide

Recommended cryptographic algorithms

Next Generation Encryption

RFCs

RFC

Title

RFC 4306

Internet Key Exchange (IKEv2) Protocol

RFC 4869

Suite B Cryptographic Suites for IPsec

RFC 5685

Redirect Mechanism for the Internet Key Exchange Protocol Version 2 (IKEv2)

Technical Assistance

Description

Link

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http://www.cisco.com/cisco/web/support/index.html

Feature Information for Configuring Internet Key Exchange Version 2 (IKEv2) and FlexVPN Site-to-Site

The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.

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Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be actual addresses and phone numbers. Any examples, command display output, network topology diagrams, and other figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses or phone numbers in illustrative content is unintentional and coincidental.

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