Restriction for SSH Algorithms for Common Criteria Certification
Starting from Cisco IOS XE Amsterdam 17.1.1, SHA1 is not supported.
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Starting from Cisco IOS XE Amsterdam 17.1.1, SHA1 is not supported.
This section provides information about the Secure Shell (SSH) Algorithms for Common Criteria Certification, the Cisco IOS SSH Server Algorithms and Cisco IOS SSH Client Algorithms.
A Secure Shell (SSH) configuration enables a Cisco IOS SSH server and client to authorize the negotiation of only those algorithms that are configured from the allowed list. If a remote party tries to negotiate using only those algorithms that are not part of the allowed list, the request is rejected and the session is not established.
Cisco IOS secure shell (SSH) servers support the encryption algorithms (Advanced Encryption Standard Counter Mode [AES-CTR], AES Cipher Block Chaining [AES-CBC], Triple Data Encryption Standard [3DES]) in the following order:
Supported Default Encryption Order:
aes128-gcm
aes256-gcm
aes128-ctr
aes192-ctr
aes256-ctr
Supported Non-Default Encrytion Order:
aes128-cbc
aes192-cbc
aes256-cbc
3des
Cisco IOS SSH clients support the Message Authentication Code (MAC) algorithms in the following order:
Supported Default HMAC order:
hmac-sha2-256-etm
hmac-sha2-512-etm
hmac-sha2-256
hmac-sha2-512
Cisco IOS SSH clients support only one host key algorithm and do not need a CLI configuration.
Supported Default Host Key order:
x509v3-ssh-rsa
rsa-sha2-512
rsa-sha2-256
ssh-rsa
Cisco IOS secure shell (SSH) clients support the encryption algorithms (Advanced Encryption Standard counter mode [AES-CTR], AES Cipher Block Chaining [AES-CBC], Triple Data Encryption Standard [3DES]) in the following order:
Supported Default Encryption Order:
aes128-gcm
aes256-gcm
aes128-ctr
aes192-ctr
aes256-ctr
Supported Non-Default Encrytion Order:
aes128-cbc
aes192-cbc
aes256-cbc
3des
Cisco IOS SSH clients support the Message Authentication Code (MAC) algorithms in the following order:
Supported Default HMAC order:
hmac-sha2-256-etm
hmac-sha2-512-etm
hmac-sha2-256
hmac-sha2-512
Cisco IOS SSH clients support only one host key algorithm and do not need a CLI configuration.
Supported Default Host Key order:
x509v3-ssh-rsa
rsa-sha2-512
rsa-sha2-256
ssh-rsa
This section provides information on how to configure and troubleshoot:
Encryption key algorithm for a Cisco IOS SSH server and client
MAC algorithm for a Cisco IOS SSH server and client
Host Key algorithm for a Cisco IOS SSH server
Command or Action | Purpose | |||||||
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Step 1 |
enable Example:
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Enables privileged EXEC mode. Enter your password if prompted. |
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Step 2 |
configure terminal Example:
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Enters global configuration mode. |
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Step 3 |
ip ssh {server | client} algorithm encryption {aes128-gcm | aes256-gcm | aes128-ctr | aes192-ctr | aes256-ctr | aes128cbc | aes192-cbs | 3des} Example:
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Defines the order of encryption algorithms in the SSH server and client. This order is presented during algorithm negotiation.
|
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Step 4 |
end Example:
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Exits global configuration mode and returns to privileged EXEC mode. |
% SSH command rejected: All encryption algorithms cannot be disabled
Command or Action | Purpose | |||||||
---|---|---|---|---|---|---|---|---|
Step 1 |
enable Example:
|
Enables privileged EXEC mode.
|
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Step 2 |
configure terminal Example:
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Enters global configuration mode. |
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Step 3 |
ip ssh {server | client} algorithm mac {hmac-sha2-256-etm | hmac-sha2-512-etm | hmac-sha2-256 | hmac-sha2-512 } Example:
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Defines the order of MAC (Message Authentication Code) algorithms in the SSH server and client. This order is presented during algorithm negotiation.
|
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Step 4 |
end Example:
|
Exits global configuration mode and returns to privileged EXEC mode. |
% SSH command rejected: All mac algorithms cannot be disabled
Command or Action | Purpose | |||||||
---|---|---|---|---|---|---|---|---|
Step 1 |
enable Example:
|
Enables privileged EXEC mode. Enter your password if prompted. |
||||||
Step 2 |
configure terminal Example:
|
Enters global configuration mode. |
||||||
Step 3 |
ip ssh server algorithm hostkey {x509v3-ssh-rsa |rsa-sha2-512| rsa-sha2-256ssh-rsa} Example:
|
Defines the order of host key algorithms. Only the configured algorithm is negotiated with the Cisco IOS secure shell (SSH) client.
|
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Step 4 |
end Example:
|
Exits global configuration mode and returns to privileged EXEC mode. |
% SSH command rejected: All hostkey algorithms cannot be disabled
This section provides configuration examples for SSH algorithms for common certification.
Device> enable
Device# configure terminal
Device(config)# ip ssh server algorithm encryption aes128-gcm aes256-gcm aes128-ctr aes192-ctr aes256-ctr aes128-cbc aes192-cbc aes256-cbc 3des
Device(config)# end
Device> enable
Device# configure terminal
Device(config)# ip ssh client algorithm encryption aes128-gcm aes256-gcm aes128-ctr aes192-ctr aes256-ctr aes128-cbc aes192-cbc aes256-cbc 3des
Device(config)# end
Device> enable
Device# configure terminal
Device(config)# ip ssh server algorithm mac hmac-sha2-256-etm hmac-sha2-512-etm hmac-sha2-256 hmac-sha2-512
Device(config)# end
Device> enable
Device# configure terminal
Device(config)# ip ssh server algorithm hostkey x509v3-ssh-rsa rsa-sha2-512 rsa-sha2-256 ssh-rsaa
Device(config)# end
Step 1 |
enable Enables privileged EXEC mode.
Example:
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Step 2 |
show ip ssh Displays configured Secure Shell (SSH) encryption, host key, and Message Authentication Code (MAC) algorithms. Example:
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This table provides release and related information for features explained in this module.
These features are available on all releases subsequent to the one they were introduced in, unless noted otherwise.
Release |
Feature |
Feature Information |
---|---|---|
Cisco IOS XE Everest 16.5.1a |
Secure Shell Algorithms for Common Criteria Certification |
The SSH Algorithms for Common Criteria Certification feature provides the list and order of the algorithms that are allowed for Common Criteria Certification. This module describes how to configure the encryption, Message Authentication Code (MAC), and host key algorithms for a secure shell (SSH) server and client so that SSH connections can be limited on the basis of the allowed algorithms list. |
Use Cisco Feature Navigator to find information about platform and software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn.