Rsa Authentication Process; Password Authentication Process; Ssh Configuration - Avaya G250 Administration Manual

RSA authentication process

The G250/G350 generates a key of variable length (512-2048 bits) using the DSA
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encryption method. This is the private key.
The G250/G350 calculates an MD5 hash of the private key, called the public key (also
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called a fingerprint). The public key is always 16 bytes long. This public key is displayed.
The G250/G350 sends the public key to the client computer. This public key is used by the
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client to encrypt the data it sends to the G250/G350. The G250/G350 decrypts the data
using the private key.
Both sides negotiate and must agree on the same chipper type. The G250/G350 only
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supports 3DES-CBC encryption. The user on the client side accepts the public key. The
client maintains a cache containing a list of fingerprints per server IP address. If the
information in this cache changes, the client notifies the user.
The client chooses a random number that is used to encrypt and decrypt the information
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sent.
This random number is sent to the G250/G350, after encryption based on the
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G250/G350's public key.
When the G250/G350 receives the encrypted random number, it decrypts it using the
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private key. This random number is now used with the 3DES-CBC encryption method for
all encryption and decryption of data. The public and private keys are no longer used.

Password authentication process

Before any data is transferred, the G250/G350 requires the client to supply a username and
password. This authenticates the user on the client side to the G250/G350.

SSH configuration

To enable SSH on the G250/G350:
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a. To execute the SSH protocol, the G250/G350 must first be assigned hostname
identification. Use the hostname command to assign hostname identification.
b. To enable SSH to be used, you must also configure the server host key. Use the
crypto key generate dsa command to generate an SSH host key pair.
c. Enter ip ssh to enable SSH authentication. Note that SSH is enabled by default.
To disable SSH on the G250/G350:
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- Use the disconnect ssh command to disconnect an existing SSH session.
- Enter no ip ssh to disable the SSH server which disconnects all active SSH
sessions.
Enter show ip ssh to display SSH configuration information and information about any
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active SSH sessions.
Managing login permissions
Issue 5 June 2008 61