RackSwitch G8000 Application Guide
Generating RSA Host and Server Keys for SSH access
To support the SSH server feature, two sets of RSA keys (host and server keys) are required. The host key is 1024 bits and is used to identify the G8000. The server key is 768 bits and is used to make it impossible to decipher a captured session by breaking into the G8000 at a later time.
When the SSH server is first enabled and applied, the switch automatically generates the RSA host and server keys and is stored in the Flash memory. To configure RSA host and server keys, enter the following commands to generate them manually.
RS G8000 (config)# ssh
RS G8000 (config)# ssh
When the switch reboots, it will retrieve the host and server keys from the Flash memory. If these two keys are not available in the flash and if the SSH server feature is enabled, the switch automatically generates them during the system reboot. This process may take several minutes to complete.
The switch can automatically regenerate the RSA server key. To set the interval of RSA server key autogeneration, use the following command:
RS G8000 (config)# ssh interval <number of hours
A value of 0 (zero) denotes that RSA server key autogeneration is disabled. When greater than 0, the switch will autogenerate the RSA server key every specified interval; however, RSA server key generation is skipped if the switch is busy doing other key or cipher generation when the timer expires.
NOTE – The switch will perform only one session of key/cipher generation at a time. Thus, an SSH client will not be able to log in if the switch is performing key generation at that time, or if another client has logged in immediately prior. Also, key generation will fail if an SSH client is logging in at that time.
SSH Integration with RADIUS/TACACS+ Authentication
SSH is integrated with RADIUS authentication. After the RADIUS server is enabled on the switch, all subsequent SSH authentication requests will be redirected to the specified RADIUS servers for authentication. The redirection is transparent to the SSH clients.
SSH is integrated with TACACS+ authentication. After the TACACS+ server is enabled on the switch, all subsequent SSH authentication requests will be redirected to the specified TACACS+ servers for authentication. The redirection is transparent to the SSH clients.
BMD00041, November 2008 | Chapter 1: Accessing the Switch 35 |
