Configuring Secure Shell (SSH)

Further Information on SSH Client Public-Key Authentication

a.Combines the decrypted byte sequence with specific session data.

b.Uses a secure hash algorithm to create a hash version of this informa- tion.

c.Returns the hash version to the switch.

7.The switch computes its own hash version of the data in step 6 and compares it to the client’s hash version. If they match, then the client is authenticated. Otherwise, the client is denied access.

Using client public-key authentication requires these steps:

1.Generate a public/private key pair for each client you want to have SSH access to the switch. This can be a separate key for each client or the same key copied to several clients.

2.Copy the public key for each client into a client-public-key text file.

3.Use copy tftp to copy the client-public-key file into the switch. Note that the switch can hold 10 keys. The new key is appended to the client public- key file

4.Use the aaa authentication ssh command to enable client public-key authentication.

To Create a Client-Public-Key Text File. These steps describe how to copy client-public-keys into the switch for RSA challenge-response authenti- cation, and require an understanding of how to use your SSH client applica- tion.

Bit Size

 

Exponent <e>

 

Modulus <n>

 

Comment

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 6-14. Example of a Client Public Key

Notes

Comments in public key files, such as smith@support.cairns.com in figure 6-14,

 

may appear in a SSH client application’s generated public key. While such

 

comments may help to distinguish one key from another, they do not pose any

 

restriction on the use of a key by multiple clients and/or users.

 

Public key illustrations such as the key shown in figure 6-14 usually include

 

line breaks as a method for showing the whole key. However, in practice, line

 

breaks in a public key will cause errors resulting in authentication failure.

 

 

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