- Finding Feature Information
- Prerequisites for IPsec Usability Enhancements
- Information About IPsec Usability Enhancements
IPsec Usability Enhancements
The IPsec Usability Enhancements feature introduces functionality that eases the configuration and monitoring of your IPsec virtual private network (VPN). Benefits of this feature include intelligent defaults for IPsec and Internet Key Exchange (IKE) and the ability to easily verify and troubleshoot IPsec VPNs.
 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
- Prerequisites for IPsec Usability Enhancements
- Information About IPsec Usability Enhancements
- How to Utilize IPsec Usability Enhancements
- Configuration Examples for IPsec Usability Enhancements
- Additional References
- Feature Information for IPsec Usability Enhancements
- Glossary
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 IPsec Usability Enhancements
- You must be familiar with IPsec, IKE, and encryption.
- You must have configured IPsec and enabled IKE on your router.
- You must be running Cisco IOS k9 crypto image on your router.
Information About IPsec Usability Enhancements
IPsec Overview
IPsec is a framework of open standards developed by the Internet Engineering Task Force (IETF), which provides security for transmission of sensitive information over public networks. IPsec acts at the network layer, protecting and authenticating IP packets between participating IPsec devices (peers), such as Cisco routers.
IPsec provides secure tunnels between two peers. You may define which packets are considered sensitive and should be sent through these secure tunnels. You may also define the parameters that should be used to protect these sensitive packets by specifying characteristics of the tunnels. When an IPsec peer detects a sensitive packet, it sets up the appropriate secure tunnel and sends the packet through the tunnel to the remote peer.
IPsecOperation
An IPsec operation involves five basic steps: identifying interesting traffic, IKE phase-1, IKE phase-2, establishing the tunnel or IPsec session, and finally tearing down the tunnel.
Step 1: Identifying Interesting Traffic
The VPN devices recognize the traffic, or sensitive packets, to detect. IPsec is either applied to the sensitive packet, the packet is bypassed, or the packet is dropped. Based on the traffic type, if IPsec is applied then IKE phase-1 is initiated.
Step 2: IKE Phase-1
There are three exchanges between the VPN devices to negotiate an IKE security policy and establish a secure channel.
During the first exchange, the VPN devices negotiate matching IKE transform sets to protect the IKE exchange resulting in establishing an Internet Security Association and Key Management Protocol (ISAKMP) policy to utilize. The ISAKMP policy consists of an encryption algorithm, a hash algorithm, an authentication algorithm, a Diffie-Hellman (DH) group, and a lifetime parameter.
There are eight default ISAKMP policies supported. For more information on default ISAKMP policies, see the section "Verifying IKE Phase-1 ISAKMP Default Policies."
The second exchange consists of a Diffie-Hellman exchange, which establishes a shared secret.
The third exchange authenticates peer identity. After the peers are authenticated, IKE phase-2 begins.
Step 3: IKE Phase-2
The VPN devices negotiate the IPsec security policy used to protect the IPsec data. IPsec transform sets are negotiated.
A transform set is a combination of algorithms and protocols that enact a security policy for network traffic. For more information on default transform sets, see the section "Verifying Default IPsec Transform-Sets." A VPN tunnel is ready to be established.
Step 4: Establishing the Tunnel--IPsec Session
The VPN devices apply security services to IPsec traffic and then transmit the IPsec data. Security associations (SAs) are exchanged between peers. The negotiated security services are applied to the tunnel traffic while the IPsec session is active.
Step 5: Terminating the Tunnel
The tunnel is torn down when an IPsec SA lifetime time-out occurs or if the packet counter is exceeded. The IPsec SA is removed.
How to Utilize IPsec Usability Enhancements
- Verifying IKE Phase-1 ISAKMP Default Policies
- Verifying Default IPsec Transform-Sets
- Verifying and Troubleshooting IPsec VPNs
Verifying IKE Phase-1 ISAKMP Default Policies
When IKE negotiation begins, the peers try to find a common policy, starting with the highest priority policy as specified on the remote peer. The peers negotiate the policy sets until there is a match. If peers have more than one policy set in common, the lowest priority number is used.
There are three groups of IKE phase-1, ISAKMP, policies as defined by policy priority ranges and behavior:
- Default ISAKMP policies, which are automatically enabled.
- User configured ISAKMP policies, which you may configure with the crypto isakmp policy command.
- Easy VPN (EzVPN) ISAKMP policies, which are made available during EzVPN configuration.
This section describes the three groups of ISAKMP policies, how they behave in relationship to one another, how to determine which policies are in use with the appropriate show command, and how to disable the default ISAKMP policies.
Default IKE Phase-1 Policies
There are eight default IKE phase-1, ISAKMP, policies supported (see the table below) that are enabled automatically. If you have neither manually configured IKE policies with the crypto isakmp policy command nor disabled the default IKE policies with the no crypto isakmp default policy command, the default IKE policies will be used during peer IKE negotiations. You can verify that the default IKE policies are in use by issuing either the show crypto isakmp policy command or the show crypto isakmp default policy command.
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. |
The default IKE policies define the following policy set parameters:
- The priority, 65507-65514, where 65507 is the highest priority and 65514 is the lowest priority.
- The authentication method, Rivest, Shamir, and Adelman (RSA) or preshared keys (PSK).
- The encryption method, Advanced Encryption Standard (AES) or Triple Data Encryption Standard (3DES).
- The hash function, Secure Hash Algorithm (SHA-1) or Message-Digest algorithm 5 (MD5).
- The DH group specification DH2 or DH5
Note |
Cisco no longer recommends using 3DES, MD5 and DH groups 1, 2 and 5. For more information about the latest Cisco cryptographic recommendations, see the Next Generation Encryption (NGE) white paper. To learn more about IKE configuration, read the chapter "Configuring Internet Key Exchange for IPsec VPNs" in Internet Key Exchange for IPsec VPNs Configuration Guide. |
| Table 1 | Default IKE Phase-1, ISAKMP, Policies |
| Priority |
Authentication |
Encryption |
Hash |
Diffie-Hellman |
|---|---|---|---|---|
| 65507 |
RSA |
AES |
SHA |
DH5 |
| 65508 |
PSK |
AES |
SHA |
DH5 |
| 65509 |
RSA |
AES |
MD5 |
DH5 |
| 65510 |
PSK |
AES |
MD5 |
DH5 |
| 65511 |
RSA |
3DES |
SHA |
DH2 |
| 65512 |
PSK |
3DES |
SHA |
DH2 |
| 65513 |
RSA |
3DES |
MD5 |
DH2 |
| 65514 |
PSK |
3DES |
MD5 |
DH2 |
User Configured IKE Policies
You may configure IKE policies with the crypto isakmp policy command. User configured IKE policies are uniquely identified and configured with a priority number ranging from 1-10000, where 1 is the highest priority and 10000 the lowest priority.
Once you have configured one or more IKE policies with a priority of 1-10000:
- The user configured policies will be used during peer IKE negotiations.
- The default IKE policies will no longer used during peer IKE negotiations.
- The user configured policies may be displayed by issuing the show crypto isakmp policy command.
EzVPN ISAKMP Policies
If you have configured EzVPN (see EzVPN ISAKMP Policies), the default EzVPN ISAKMP policies in use are uniquely identified with a priority number ranging from 65515-65535, where 65515 is the highest priority and 65535 is the lowest priority.
Once a user has configured EzVPN:
- The default EzVPN ISAKMP policies and the default IKE policies will be used during peer IKE negotiations.
- The EzVPN IKAKMP policies and the default IKE policies will be displayed by issuing the show crypto isakmp policy command.
- Default ISAKMP policies will be displayed by issuing the show crypto isakmp default policy command unless they have been disabled by issuing the no crypto isakmp default policy command.
DETAILED STEPS
Examples
The following is sample output of the show crypto isakmp default policy command. The default policies are displayed because the default policies have not been disabled.
Router# show crypto isakmp default policy
Default IKE policy
Default protection suite of priority 65507
encryption algorithm: AES - Advanced Encryption Standard (128 bit key.
hash algorithm: Secure Hash Standard
authentication method: Rivest-Shamir-Adleman Signature
Diffie-Hellman group: #5 (1536 bit)
lifetime: 86400 seconds, no volume limit
Default protection suite of priority 65508
encryption algorithm: AES - Advanced Encryption Standard (128 bit key.
hash algorithm: Secure Hash Standard
authentication method: Pre-Shared Key
Diffie-Hellman group: #5 (1536 bit)
lifetime: 86400 seconds, no volume limit
Default protection suite of priority 65509
encryption algorithm: AES - Advanced Encryption Standard (128 bit key.
hash algorithm: Message Digest 5
authentication method: Rivest-Shamir-Adleman Signature
Diffie-Hellman group: #5 (1536 bit)
lifetime: 86400 seconds, no volume limit
Default protection suite of priority 65510
encryption algorithm: AES - Advanced Encryption Standard (128 bit key.
hash algorithm: Message Digest 5
authentication method: Pre-Shared Key
Diffie-Hellman group: #5 (1536 bit)
lifetime: 86400 seconds, no volume limit
Default protection suite of priority 65511
encryption algorithm: Three key triple DES
hash algorithm: Secure Hash Standard
authentication method: Rivest-Shamir-Adleman Signature
Diffie-Hellman group: #2 (1024 bit)
lifetime: 86400 seconds, no volume limit
Default protection suite of priority 65512
encryption algorithm: Three key triple DES
hash algorithm: Secure Hash Standard
authentication method: Pre-Shared Key
Diffie-Hellman group: #2 (1024 bit)
lifetime: 86400 seconds, no volume limit
Default protection suite of priority 65513
encryption algorithm: Three key triple DES
hash algorithm: Message Digest 5
authentication method: Rivest-Shamir-Adleman Signature
Diffie-Hellman group: #2 (1024 bit)
lifetime: 86400 seconds, no volume limit
Default protection suite of priority 65514
encryption algorithm: Three key triple DES
hash algorithm: Message Digest 5
authentication method: Pre-Shared Key
Diffie-Hellman group: #2 (1024 bit)
lifetime: 86400 seconds, no volume limit
The following example disables the default IKE policies then shows the resulting output of the show crypto isakmp default policy command, which is blank:
Router# configure terminal Router(config)# no crypto isakmp default policy Router(config)# exit Router# show crypto isakmp default policy Router# !There is no output since the default IKE policies have been disabled.
The following is an example system log message that is generated whenever the default ISAKMP policies are in use:
%CRYPTO-6-IKMP_POLICY_DEFAULT: Using ISAKMP Default policies
Verifying Default IPsec Transform-Sets
A transform set represents a certain combination of security protocols and algorithms. During the IPsec SA negotiation, the peers agree to use a particular transform set for protecting a particular data flow.
During IPsec SA negotiations with IKE, the peers search for a transform set that is the same at both peers. When such a transform set is found, it is selected and is applied to the protected traffic as part of the IPsec SAs of both peers.
Default Transform Sets
A default transform set will be used by any crypto map or IPsec profile where no other transform set has been configured and if the following is true:
- The default transform sets have not been disabled with the no crypto ipsec default transform-set command.
- The crypto engine in use supports the encryption algorithm.
The two default transform sets each define an Encapsulation Security Protocol (ESP) encryption transform type and an ESP authentication transform type as shown in the table below.
| Table 2 | Default Transform Sets and Parameters |
| Default Transform Name |
ESP Encryption Transform and Description |
ESP Authentication Transform and Description |
|---|---|---|
| #$!default_transform_set_0 |
esp-3des (ESP with the 168-bit 3DES or Triple DES encryption algorithm) |
esp-sha-hmac |
| #$!default_transform_set_1 |
esp-aes (ESP with the 128-bit AES encryption algorithm) |
esp-sha-hmac (ESP with the SHA-1, hash message authentication code [HMAC] variant authentication algorithm) |
DETAILED STEPS
Examples
The following example displays output from the show crypto ipsec default transform-set command when the default transform sets are enabled, the default setting: Router# show crypto ipsec default transform-set Transform set #$!default_transform_set_1: { esp-aes esp-sha-hmac } will negotiate = { Transport, }, Transform set #$!default_transform_set_0: { esp-3des esp-sha-hmac } will negotiate = { Transport, },
The following example displays output from the show crypto ipsec default transform-set command when the default transform sets have been disabled with the no crypto ipsec default transform-setcommand.
Router(config)# no crypto ipsec default transform-set Router(config)# exit Router# Router# show crypto ipsec default transform-set ! There is no output. Router#
The following is an example system log message that is generated whenever IPsec SAs have negotiated with a default transform set:
%CRYPTO-5-IPSEC_DEFAULT_TRANSFORM: Using Default IPsec transform-set
Verifying and Troubleshooting IPsec VPNs
Perform one of the following optional tasks in this section, depending on whether you want to verify IKE phase-1 or IKE phase-2 tunnels or troubleshoot your IPsec VPN:
Verifying IKE Phase-1 ISAKMP
To display statistics for ISAKMP tunnels, use the following optional commands.
DETAILED STEPS
What to Do Next
Verifying IKE Phase-2
To display statistics for IPsec phase-2 tunnels, use the following optional commands.
DETAILED STEPS
Troubleshooting IPsec VPNs
The show tech-support ipsec command simplifies the collection of the IPsec related information if you are troubleshooting a problem.
DETAILED STEPS
|
There are three variations of the show tech-support ipseccommand:
For a sample display of the output from the show tech-support ipsec command for the individual show commands listed below for each variation see the "Troubleshooting IPsec VPNs" section. Output of the show tech-support ipsec Command If you enter the show tech-support ipseccommand without any keywords, the command output displays the following show commands, in order of output:
Output of the show tech-support ipsec peer Command If you enter the show tech-support ipseccommand with the peer keyword and the ipv4address argument, the output displays the following show commands, in order of output for the specified peer:
Output of the show tech-support ipsec vrf Command If you enter the show tech-support ipseccommand with the vrf keyword and the vrf-nameargument, the output displays the following show commands, in order of output for the specified Virtual Routing and Forwarding (VRF):
Example: |
Configuration Examples for IPsec Usability Enhancements
IKE Default Policies Example
In the following example, crypto maps are configured on RouterA and RouterB and default IKE policies are in use. Traffic is routed from Pagent A to Pagent B. Checking the system log on Peer A and Peer B confirms that the default IKE policies are in use on both peers (see the figure below).
| Figure 1 | Example Site to Site Topology |
! Configuring RouterA. RouterA(config)# crypto isakmp key identity address 209.165.200.226 RouterA(config)# crypto map testmap 10 ipsec-isakmp % NOTE: This new crypto map will remain disabled until a peer and a valid access list have been configured. RouterA(config-crypto-map)# set peer 209.165.200.226 RouterA(config-crypto-map)# match address 101 RouterA(config-crypto-map)# exit RouterA(config)# ip route 209.165.200.225 255.255.255.224 209.165.200.226 RouterA(config)# access-list 101 permit ip host 209.165.200.227 host 209.165.200.225 RouterA(config)# end RouterA(config)# interface Ethernet1/2 RouterA(config-if)# crypto map testmap RouterA(config-if)# end RouterA(config)# crypto ipsec transform test_transf esp-aes esp-sha-hmac RouterA(cfg-crypto-trans)# mode tunnel RouterA(cfg-crypto-trans)# end RouterA(config)# crypto map testmap 10 RouterA(config-crypto-map)# set transform-set test_transf RouterA(config-crypto-map)# end ! Configuring RouterB. RouterB(config)# crypto isakmp key identity address 209.165.200.228 RouterB(config)# crypto dynamic-map dyn_testmap 10 RouterB(config-crypto-map)# crypto map testmap 10 ipsec-isakmp dynamic dyn_testmap RouterB(config)# ip route 209.165.200.227 255.255.255.224 209.165.200.228 RouterB(config)# end RouterB(config)# interface GigabitEthernet0/1 RouterB(config-if)# crypto map testmap RouterB(config-if)# end RouterB(config)# crypto ipsec transform test_transf esp-aes esp-sha-hmac RouterB(cfg-crypto-trans)# mode tunnel RouterB(cfg-crypto-trans)# end RouterB(config)# crypto dynamic-map dyn_testmap 10 RouterB(config-crypto-map)# set transform-set test_transf RouterB(config-crypto-map)# end ! Routing traffic from PagentA to PagentB. PagentA(config)# ip route 209.165.200.225 255.255.255.224 209.165.200.229 PagentA(config)# end ! Routing traffic from PagentB to PagentA. PagentB(config)# ip route 209.165.200.227 255.255.255.224 209.165.200.230 PagentB(config)# end ! Checking the system log on RouterA confirms that the default IKE policies are in use. RouterA# show log | include %CRYPTO-6-IKMP_POLICY_DEFAULT* Jun 5 09:17:59.251 PDT: %CRYPTO-6-IKMP_POLICY_DEFAULT: Using ISAKMP Default policies ! Checking the system log on RouterB confirms that the default IKE policies are in use. RouterB# show log | include %CRYPTO-6-IKMP_POLICY_DEFAULT* Jun 5 09:17:59.979 PDT: %CRYPTO-6-IKMP_POLICY_DEFAULT: Using ISAKMP Default policies
Default Transform Sets Example
In the following example, static crypto maps are configured on RouterA and dynamic crypto maps are configured on RouterB. Traffic is routed from Pagent A to Pagent B. The IPsec SAs negotiate with default transform sets and the traffic is encrypted. Executing the show crypto map command on both peers verifies that the default transform sets are in use (see Default Transform Sets Example).
! Configuring RouterA. RouterA(config)# crypto isakmp key identify address 209.165.200.225 RouterA(config)# crypto map testmap 10 ipsec-isakmp % NOTE: This new crypto map will remain disabled until a peer and a valid access list have been configured. RouterA(config-crypto-map)# set peer 209.165.200.225 RouterA(config-crypto-map)# match address 101 RouterA(config-crypto-map)# exit RouterA(config)# ip route 209.165.200.226 255.255.255.255 209.165.200.225 RouterA(config)# access-list 101 permit ip host 209.165.200.227 host 209.165.200.226 RouterA(config)# end RouterA(config)# interface Ethernet1/2 RouterA(config-if)# crypto map testmap RouterA(config-if)# end RouterA(config)# crypto isakmp policy 10 RouterA(config-isakmp)# encryption aes RouterA(config-isakmp)# authentication pre-share RouterA(config-isakmp)# hash sha RouterA(config-isakmp)# group 14 RouterA(config-isakmp)# end ! Configuring RouterB. RouterB(config)# crypto isakmp key identity address 209.165.200.229 RouterB(config)# crypto dynamic-map dyn_testmap 10 RouterB(config-crypto-map)# crypto map testmap 10 ipsec-isakmp dynamic dyn_testmap RouterB(config)# ip route 209.165.200.227 255.255.255.255 209.165.200.229 RouterB(config)# end RouterB(config)# interface GigabitEthernet0/1 RouterB(config-if)# crypto map testmap RouterB(config-if)# end RouterB(config)# crypto isakmp policy 10 RouterB(config-isakmp)# encryption aes RouterB(config-isakmp)# authentication pre-share RouterB(config-isakmp)# hash sha RouterB(config-isakmp)# group 14 RouterB(config-isakmp)# end ! The SA is using the default transform set and traffic is encrypted on RouterA. RouterA# show crypto isakmp sa detail | include 209.165.200.229.*209.165.200.225.*ACTIVE 13007 209.165.200.229 209.165.200.225 ACTIVE aes sha psk 14 23:59:56 13006 209.165.200.229 209.165.200.225 ACTIVE aes sha psk 14 0 13005 209.165.200.229 209.165.200.225 ACTIVE aes sha psk 14 0 ! The SA is using the default transform set and traffic is encrypted on RouterB. RouterB# show crypto isakmp sa detail | include 209.165.200.225.*209.165.200.229.*ACTIVE 7007 209.165.200.225 209.165.200.229 ACTIVE aes sha psk 14 23:59:55 7006 209.165.200.225 209.165.200.229 ACTIVE aes sha psk 14 0 7005 209.165.200.225 209.165.200.229 ACTIVE aes sha psk 14 0 ! Verifying that the default transform sets are in use on RouterA. RouterA# show crypto map Crypto Map "testmap" 10 ipsec-isakmp Peer = 209.165.200.225 Extended IP access list 101 access-list 101 permit ip host 209.165.200.227 host 209.165.200.226 Current peer: 209.165.200.225 Security association lifetime: 4608000 kilobytes/3600 seconds PFS (Y/N): N Transform sets={ #$!default_transform_set_1: { esp-aes esp-sha-hmac } , #$!default_transform_set_0: { esp-3des esp-sha-hmac } , } Interfaces using crypto map testmap: Ethernet1/2 ! Verifying that the default transform sets are in use on RouterB. RouterB# show crypto map Crypto Map "testmap" 10 ipsec-isakmp Dynamic map template tag: dyn_testmap Crypto Map "testmap" 65536 ipsec-isakmp Peer = 209.165.200.229 Extended IP access list access-list permit ip host 209.165.200.226 host 209.165.200.227 dynamic (created from dynamic map dyn_testmap/10) Current peer: 209.165.200.229 Security association lifetime: 4608000 kilobytes/3600 seconds PFS (Y/N): N Transform sets={ #$!default_transform_set_1: { esp-aes esp-sha-hmac } , } Interfaces using crypto map testmap: GigabitEthernet0/1
Additional References
Related Documents
| Related Topic |
Document Title |
|---|---|
| IKE configuration |
Configuring Internet Key Exchange for IPsec VPNs |
| IPsec configuration |
Configuring Security for VPNs with IPsec |
| EzVPN server |
Easy VPN Server |
| Cisco IOS security commands |
Cisco IOS Security Command Reference |
| Recommended cryptographic algorithms |
MIBs
| MIB |
MIBs Link |
|---|---|
| None. |
To locate and download MIBs for selected platforms, Cisco IOS software releases, and feature sets, use Cisco MIB Locator found at the following URL: |
Technical Assistance
| Description |
Link |
|---|---|
| The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password. |
Feature Information for IPsec Usability Enhancements
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.
| Table 3 | Feature Information for IPsec Usability Enhancements |
| Feature Name |
Releases |
Feature Information |
|---|---|---|
| IPsec Usability Enhancements |
12.4(20)T Cisco IOS XE Release 2.4 |
The IPsec Usability Enhancements feature introduces functionality that eases the configuration and monitoring of your IPsec virtual private network (VPN). Benefits of this feature include intelligent defaults for IPsec and Internet Key Exchange (IKE) and the ability to easily verify and troubleshoot IPsec VPNs. In Cisco IOS Release XE 2.4, this feature was implemented on the Cisco ASR 1000 series routers. The following commands were introduced or modified: crypto ipsec default transform-set, crypto isakmp default policy, crypto isakmp policy, show crypto ipsec default transform-set, show crypto ipsec transform-set, show crypto isakmp default policy, show crypto isakmp policy, show crypto map (IPsec), show crypto mib ipsec flowmib endpoint, show crypto mib ipsec flowmib failure, show crypto mib ipsec flowmib global, show crypto mib ipsec flowmib history, show crypto mib ipsec flowmib spi, show crypto mib ipsec flowmib tunnel, show crypto mib isakmp flowmib failure, show crypto mib isakmp flowmib global, show crypto mib isakmp flowmib history, show crypto mib isakmp flowmib peer, show crypto mib isakmp flowmib tunnel, show tech-support ipsec. |
Glossary
peer--In the context of this module, a router or other device that participates in IPsec.
SA --security association. Description of how two or more entities use security services in the context of a particular security protocol (AH or ESP) to communicate securely on behalf of a particular data flow. The transform and the shared secret keys are used for protecting the traffic.
transform --List of operations performed on a dataflow to provide data authentication, data confidentiality, and data compression. For example, one transform is the ESP protocol with the HMAC-MD5 authentication algorithm; another transform is the AH protocol with the 56-bit DES encryption algorithm and the ESP protocol with the HMAC-SHA authentication algorithm.
tunnel --In the context of this module, a secure communication path between two peers, such as two routers. It does not refer to using IPsec in tunnel mode.
Cisco and the Cisco logo are trademarks or registered trademarks of Cisco and/or its affiliates in the U.S. and other countries. To view a list of Cisco trademarks, go to this URL: www.cisco.com/go/trademarks. Third-party trademarks mentioned are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company. (1110R)
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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