Configuring Secure Shell (SSH)

Configuring the Switch for SSH Operation

For example, to generate and display a new key:

Host Public

Key for the

Switch

Version 1 and Version 2 Views

of Same Host Public Key

Figure 6-6. Example of Generating a Public/Private Host Key Pair for the Switch

The 'show crypto host-public-key' displays data in two different formats because your client may store it in either of these formats after learning the key. If you wish to compare the switch key to the key as stored in your client's known-hosts file, note that the formatting and comments need not match. For version 1 keys, the three numeric values bit size, exponent <e>, and modulus <n> must match; for PEM keys, only the PEM-encoded string itself must match.

Notes

"Zeroizing" the switch’s key automatically disables SSH (sets ip ssh to no).

 

Thus, if you zeroize the key and then generate a new key, you must also re-

 

enable SSH with the ip ssh command before the switch can resume SSH

 

operation.

 

 

3. Provide the Switch’s Public Key to Clients

When an SSH client contacts the switch for the first time, the client will challenge the connection unless you have already copied the key into the client’s "known host" file. Copying the switch’s key in this way reduces the chance that an unauthorized device can pose as the switch to learn your access passwords. The most secure way to acquire the switch’s public key for

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