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Configuring dsa challenge-response authentication, Providing the public key to clients – Brocade BigIron RX Series Configuration Guide User Manual

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BigIron RX Series Configuration Guide

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Configuring SSH

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By default, public keys are hidden in the running configuration. You can optionally configure the
device to display the DSA host key pair in the running configuration file entering the following
command.

BigIron RX# ssh show-host-keys

Syntax: ssh show-host-keys

To hide the public keys in the running configuration file, enter the following command.

BigIron RX# ssh no-show-host-keys

Syntax: ssh no-show-host-keys

Providing the public key to clients

If you are using SSH to connect to a device from a UNIX system, you may need to add the device’s
public key to a “known hosts” file; for example, $HOME/.ssh/known_hosts. The following is an
example of an entry in a known hosts file.

Configuring DSA challenge-response authentication

With DSA challenge-response authentication, a collection of clients’ public keys are stored on the
device. Clients are authenticated using these stored public keys. Only clients that have a private
key that corresponds to one of the stored public keys can gain access to the device using SSH.

When DSA challenge-response authentication is enabled, the following events occur when a client
attempts to gain access to the device using SSH.

1. The client sends its public key to the device.

2. The device compares the client’s public key to those stored in memory.

3. If there is a match, the device uses the public key to encrypt a random sequence of bytes.

4. The device sends these encrypted bytes to the client.

5. The client uses its private key to decrypt the bytes.

6. The client sends the decrypted bytes back to the device.

7. The device compares the decrypted bytes to the original bytes it sent to the client. If the two

sets of bytes match, it means that the client’s private key corresponds to an authorized public
key, and the client is authenticated.

Setting up DSA challenge-response authentication consists of the following steps.

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