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Advanced CLI

Fine-Tune SSH/Telnet CLI Parameters

IP Fabric’s discovery is primarily using the Command-Line Interface (CLI) to discover network elements. The CLI parameters can be found in Settings → Discovery & Snapshots → Discovery Settings → Advanced CLI.

CLI Settings

Network Device Login Timeout

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

Network Device Session Timeout

Too many Command Timeout errors during the Discovery process may indicate that Network device session timeout is too short, and the session is closed before the response arrives. It may be necessary to increase this timeout.

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. For example, this may happen 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.

Example of Error Message in Connectivity Report

According to the summary of issues in the very first completed snapshot, the CLI Settings can be adjusted. Here are some of the most common errors and adjustments:

Error Error Type How To Mitigate
connect ETIMEDOUT XX.XX.XX.XX:22 Connection error Received no response from the destination.
connect ECONNREFUSED XX.XX.XX.XX:22 Connection error The connection to the destination is being blocked by an access-list or firewall.
All configured authentication methods failed Authentication error Unable to authenticate to the destination host
Authentication failed Authentication error Unable to authenticate to the destination host
Authentication failed - login prompt appeared again Authentication error Unable to authenticate to the destination host
SSH client not received any data for last 120000 ms! cmd => show vrrp \| e #^$ Command timeout The command show vrrp \| e #^$ timed out. Increase device session timeout.
Can’t detect prompt Command timeout Unable to detect CLI prompt. Increase network device login timeout.
Command “enable” authorization failed, tried 2x Command authorization failure The command wasn’t authorized. Increase command authorization failure retries or increase the timer value (ms)

Custom SSH/Telnet Ports

Info

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

In the following example, we configure the discovery process to use port 8080 for SSH connections to 192.168.168.10:

Add custom SSH/Telnet port

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

Custom SSH/Telnet ports

Telnet/SSH URL Handler On MS Windows 7 And Later

If you want to be able to connect directly to a device from the IP Fabric web interface, you need to register a Telnet/SSH URL handler. You will be touching Windows Registry, please, be sure that you know what you are doing, have appropriate backups, and are comfortable in doing so.

Backup Windows Registry

  1. Click Start, type regedit.exe in the search box, and then press Enter
  2. In Registry Editor, click File → Export
  3. In the Export Registry File box, select the location where you want to save the backup copy, name your backup file, and click Save

Putty

Download Putty

  1. Go to https://www.chiark.greenend.org.uk/~sgtatham/putty/latest.html
  2. Download Putty
  3. This tutorial expects Putty in C:\Program Files (x86)\putty.exe

Register Telnet/SSH URL Handler

  1. Go to https://gist.github.com/sbiffi/11256316
  2. Download putty.reg file
  3. Edit path to Putty if differs from C:\Program Files (x86)\putty.exe
  4. Download putty.vbs (save it to C:\putty.vbs or change this path in putty.reg above)
  5. Edit path to Putty if differs from C:\Program Files (x86)\putty.exe
  6. Launch putty.reg to associate ssh:// and telnet:// to this script

SecureCRT

Download SecureCRT

SecureCRT is not free software. To obtain SecureCRT license please visit https://www.vandyke.com/products/securecrt/

Register Telnet/SSH URL Handler

  1. Download securecrt.reg
  2. Edit path to SecureCRT if differs from C:\Program Files\VanDyke Software\SecureCRT\SecureCRT.exe
  3. Launch securecrt.reg to associate ssh:// and telnet:// to this script