06 - CLI Settings

Fine-Tune SSH/telnet CLI parameters

The IP Fabric's discovery is primarily using the Command Line Interface (CLI) to discover network elements. There are certain default CLI parameters that can be found in Settings → Advanced → SSH/TELNET:

Network device login timeout

Timeout before the logging prompt is received. It may take longer for remote branches over low-speed lines, or destined to overloaded devices.

Network device session timeout

Too many Command Timeout errors during the Discovery process may indicate that Network device session timeout is too short and it may be necessary to expect a delay for a response to arrive.

Maximum number of parallel sessions

To prevent flooding your network with too many SSH/TELNET sessions set Maximum number of parallel sessions. This setting can be also helpful if the AAA server (TACACS/Radius) has a limit of parallel AAA requests for users.

In rare cases, the Cisco ISE or similar systems may rate limit the command authorization. When there are too many authorization failures and Cisco ISE is in place, try to limit the number of parallel sessions down to 10 and steadily increase.

Basic failure

How many times to retry a connection for any error, except authentication failure.

Authentication failure

Authentication failure can occur even if a user is authorized to login but may happen, for example, when an AAA server is overloaded or an authentication packet is lost.

Command Authorization Failure retries

If you see many examples of Authentication error during the Discovery process, please adjust Authentication failure and Command Authorization Failure retries.

Jump host

Jump host allows to set-up connection to the server which can be used as a proxy server for discovery purposes. For connecting, IP Fabric uses the sshuttle library that has the following requirements for the jump hosts.

Set up Jump host

1. Open jump host settings, using Settings → Advanced → SSH/TELNET

2. At the bottom of the page, please select the Add button

   

3. Fill in all necessary data

   1. Label - the name for configuration (mandatory) 2. Jump host Address - IP address of FQDN name (mandatory) 3. IPv4 subnets - subnet in CIDR representation, allows adding more than open, separated with spaces (mandatory) 4. Exclude IPv4 subnets - subnet to exclude in CIDR representation, allows to add more than open, separated with spaces (optional) 5. Login type 1. Use credentials - require to provide username and password 2. Use SSH keys - if you copied ssh public key to the proxy server, it won’t require providing a password (please jump to the SSH key configuration section) 6. Username - Username for authentication (mandatory) 7. Password - password for authentication (mandatory if ‘Use credentials’ is used)

     ![Jump host auth](jumphost_auth.png)
   

4. Click Add.

5. If a connection is open, you will see the Running status in Jumphost list

   

SSH key configuration

1. Download ssh key from Jumphost settings

   

2. Save ipf-discovery-public-key.pub

3. Copy file content to ~/.ssh/authorized_keys (or equivalent) file of the user that will authenticate with the Jumphost server.

4. If the key has been copied you can use the option Use SSH keys while adding a new Jumphost server, instead of Use credentials.

Disabling Jumphost connection

1. Edit configuration that needs to be disabled, i.e.

   

2. Change the setting to Disabled,

3. Click the Update button

   

Remove Jumphost configuration

1. On Jumphost servers list, check the configuration that needs to be removed

2. Click the Delete button

   

Discovery with Jumphost issues

Custom SSH/Telnet ports

Custom SSH/Telnet ports settings enable the discovery process to use different than standard ports for connecting. The standard for SSH is port 22 and 23 for Telnet.

In the following example we will configure the discovery process to use port 8080 for SSH connections towards a firewall at 192.168.168.10:

As a result of such a configuration, we would create a new item under the Custom SSH/Telnet ports configuration, which will be applied to every new snapshot created by IP Fabric.