When you add a device, Network Automation Software (NA):

1. Auto-detects and assigns the correct device driver to enable communication with the device. This process is called Driver Discovery.
2. Takes a snapshot of the device to collect the system information and initial configuration.
3. Runs the set of core diagnostics, such as “NA Interfaces” and “NA Routing Table”.

To successfully discover and snapshot a device, NA requires full access to the device, and may also require SNMP read access to the device.

Keep in mind that console servers are used to provide access to devices that are not currently reachable on the IP network, and may only be reachable via a serial connection over the device’s console port, for example devices with either a hardware failure, located in protected networks, or that do not run the IP protocol (IPX, ATM, and so on).

If you want to use a standard console server, for example a Cisco AS5xxx, that uses SSH authentication, you can connect from the console server to the target device by Telneting to the console server loopback address with the appropriate port number. To do this, you must:

• Configure the desired device(s) to use the SSH connection method.
• Configure the desired devices to use bastion host access. Be sure to provide the address and credentials for the console server as the bastion host.
• Set the device to use device-specific credentials (since in this case each device will have a different target port).
• Configure the appropriate access variables on each affected device. These variables might include:
  • hop_prompt = > (The Cisco console server prompt.)
  • hop_target_connect_protocol = telnet (Use Telnet to connect from console server to target device.)
  • hop_telnet_cmd_host = <loopback IP> (IP address of the loopback on the console server.)
  • hop_telnet_cmd_port = <device port> (Port number of the target device on the console server.)

Telnet Console servers with simple authentication, where the target device is still specified by port, can be supported using a set of Access Variable console_xxx. More complex Telnet console server configurations could require the use of customized bastion host access.

A bastion host is a host that has elevated privileges to access sections of a protected network that most other hosts cannot. This enables a management system to use a bastion host as a “hop” in managing elements on the protected network for which the bastion host has privileges. Typically, a bastion host is used for Internet and DMZ routers/switches, Extranet partners, and secured and/or private networks.

In both cases, NA uses console servers and bastion hosts as a means of accessing a device (usually via the CLI) to perform its normal management functions when other access methods, for example Telnet, SSH, FTP/TFTP, and SNMP, are not available.

If all access methods are enabled, NA uses the following order to access devices: SSH, Telnet, SNMP, and Console. NA also performs file transfers before screen scrapes. For example, SSH+SCP, SSH+TFTP, SSH+Screen Scrape, Telnet+SCP, Telnet+TFTP, Telnet+Screen Scrape, SNMP+TFTP, and Console+Screen Scrape.

For more information, refer to this link :

https://docs.microfocus.com/doc/Network_Automation/2022.05/ManageDevices2