(As a more secure alternative, the client can be directly connected to the switch serial port to download the switch public key into the client.)
If it is safe to assume that an unauthorized device is not using the switch IP address in an attempt to gain access to the client's data or network, the connection can be accepted. To enhance security also configure local, TACACS+, or RADIUS authentication at the enable (manager) level.Īt the first contact between the switch and an SSH client, if the switch public key has not been copied into the client, then the client's first connection to the switch will question the connection and, for security reasons, provide the option of accepting or refusing. When configured for SSH, the switch uses its host public key to authenticate itself to SSH clients.For SSH clients to authenticate themselves to the switch, configure SSH on the switch for client public-key authentication at the login (operator) level. If not yet done, see Generate the switch public and private key pair. NOTE: Before enabling SSH on the switch you must generate the switch public/private key pair. After you enable SSH, the switch can authenticate itself to SSH clients. The ip ssh command enables or disables SSH on the switch, and modifies parameters the switch uses for transactions with clients. The switch always uses an ASCII version of its public key, without babble or fingerprint conversion, for file storage and default display format.Įnable SSH on the switch and anticipate SSH client contact behavior. These hashes do not correspond to different keys, but differ only because of the way v1 and v2 clients compute the hash of the same RSA key. The 'babble' and 'fingerprint' options produce two hashes for the key-one that corresponds to the challenge hash you will see if connecting with a v1 client, and the other corresponding to the hash you will see if connecting with a v2 client. The two commands shown in Visual phonetic and hexadecimal conversions of the switch public key convert the displayed format of the switch (host) public key for easier visual comparison of the switch public key to a copy of the key in a client's "known host" file. Erasing the key pair automatically disables SSH. To generate or erase the switch public/private host key pair:īecause the host key pair is stored in flash instead of the running-config file, it is not necessary to use write memory to save the key pair. However, any active SSH sessions will continue to run, unless explicitly terminated with the CLI kill command. To verify whether SSH is enabled, execute show ip ssh. Removing (zeroing) the switch public/private key pair renders the switch unable to engage in SSH operation and automatically disables IP SSH on the switch. Otherwise, you must re-introduce the switch public key on all management stations you have set up for SSH access to the switch using the earlier pair. Consider this key pair to be "permanent" and avoid re-generating the key pair without a compelling reason. Also, the switch maintains the key pair across reboots, including power cycles. NOTE: When generating a host key pair on the switch, the switch places the key pair in flash memory and not in the running-config file. It is a temporary, internally generated pair used for a particular switch/client session, and then discarded.) (The session key pair mentioned above is not visible on the switch. See the documentation for your SSH client application for more details. Other SSH applications require you to manually create a known hosts file and place the switch public key in the file. Some SSH client applications automatically add the switch public key to a "known hosts" file. The public key should be added to a "known hosts" file (for example, $HOME/.ssh/known_hosts on UNIX systems) on the SSH clients which should have access to the switch. The host key pair is stored in the switch flash memory, and only the public key in this pair is readable. The switch uses this key pair along with a dynamically generated session key pair to negotiate an encryption method and session with an SSH client trying to connect to the switch. Generate the switch public and private key pair.Ī public and private host key pair must be generated on the switch.
#How to change host key for ssh on mac password
Please retype new password for manager: *******
Please retype new password for operator: ********
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