Failover to Managed Device¶

The Control Center provides users with the ability to open SSH connections to Local Managers that pass through to the console port of a managed device via the Terminal Application. Under normal circumstances, the Terminal Application establishes an SSH connection to the Local Manager. In the unusual event that the terminal is unable to establish an SSH connection to the Local Manager, the failover feature allows configuration of the Terminal Application so that it fails over to establishing an SSH connection directly to the managed device.

Note

Many of the valuable Lantronix features such as session logs, events, and configuration rollback become unavailable when the Terminal Application fails over to connecting directly to the managed device, as the Local Manager is out of the connection loop in this scenario.

Device Properties¶

This feature is activated by adding one or both of the following device properties to the Local Manager port for the managed device.

_applet_failover_ssh_fingerprint¶

Defines the SSH fingerprint for the managed device.

The Terminal App will only establish a failover SSH connection to the managed device if the fingerprint it receives from the managed device matches the fingerprint value stored in this device property.

This property can be configured through the Local Manager CLI and via the Control Center.

_applet_failover_ssh_ip¶

Defines the IP address that the Terminal Application should attempt to establish an SSH session to in the case where the terminal fails to connect to the Local Manager.

This property is only required if a management IP address is not defined for the managed device within the Local Manager or Control Center.

If a management IP address exists for the managed device and this property is not defined, then the Terminal Application will attempt the failover SSH connection to the defined management IP address.

If this property IS specified/defined, then the Terminal Application failover feature will use the IP address contained in this property rather than the management IP address.

This property can be configured through the Local Manager CLI and via the Control Center.

Example¶

The following example walks through the process of configuring Terminal Application Failover to a Cisco 3925 router connected to port 1/2 of the Local Manager.

Determine the SSH Fingerprint for the Managed Device¶

Part of enabling Terminal App failover to the managed device involves configuring the Local Manager with the SSH fingerprint of the managed device. Initiate an SSH session to the managed device via a terminal session or application such as PuTTY. The managed device fingerprint will display with a question asking whether to continue connecting. This assumes the PC/workstation does not have the managed device's RSA key in its known host file. If the fingerprint is not presented with a question asking whether to continue, then edit the SSH known host file on your PC/workstation to remove the entry for the managed device. Here is an example using a Linux, Unix or Mac terminal session:

/Users/admin > ssh admin@192.0.2.100
The authenticity of host '192.0.2.100 (192.0.2.100)' can't be established.
RSA key fingerprint is b7:b7:9b:ce:bc:44:82:36:ca:92:71:65:fe:fd:4f:43.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '192.0.2.100' (RSA) to the list of known hosts.

An example of the fingerprint in a PuTTY popup window is shown below:

Copy the SSH fingerprint. It is a required device property that will be set up in the next step.

Configure Device Properties via the Local Manager CLI¶

Log into the Local Manager and navigate to the port that is to be configured for Terminal Application failover and enter the device property editor by issuing the following commands:

[admin@LantronixLM]# port 1/2
LRT-3925 cisco CISCO3925-CHASSIS IOS 15.1(4)M
         3925
[admin@LantronixLM (port1/2)]# config properties
[config properties]#

Configure the _applet_failover_ssh_fingerprint device property for the managed device SSH fingerprint (determined in the previous step) with the following command (where there is a space between the property and the fingerprint value):

[config properties]# _applet_failover_ssh_fingerprint b7:b7:9b:ce:bc:44:82:36:ca:92:71:65:fe:fd:4f:43
[config properties]# show
_applet_failover_ssh_fingerprint: b7:b7:9b:ce:bc:44:82:36:ca:92:71:65:fe:fd:4f:43

If there is no management IP address for the managed device configured in the Local Manager, or if the failover IP address that should be used is different from the configured management IP address, then the _applet_failover_ssh_ip device property should be configured to specify the failover IP address for the managed device. The show info command can be used to determine the management IP address for a given device. The following example shows the managed device to have a management IP address of 192.0.2.100:

[admin@LantronixLM (port1/2)]# show info
Hostname: LRT-3925
Description: 3925
Make: cisco
Model: CISCO3925-CHASSIS
OS: IOS
OS Version: 15.1(4)M
Management IP: 192.0.2.100
Current CPU Utilization: 0%
CPU Utilization (1 minute average): 1%
CPU Utilization (5 minute average): 1%
Total Memory: 762273884 bytes
Used Memory: 52811412 bytes
Free Memory: 709462472 bytes

To demonstrate how to set this device property, suppose that the Terminal Application should fail over to IP address 192.0.2.200 if a SSH session cannot be established to the Local Manager. Issue the following commands to enter the device property configuration editor on the managed device port and set the failover IP address:

[admin@LantronixLM (port1/2)]# config properties
[config properties]# _applet_failover_ssh_ip 192.0.2.200
[config properties]# show
_applet_failover_ssh_ip: 192.0.2.200
_applet_failover_ssh_fingerprint: b7:b7:9b:ce:bc:44:82:36:ca:92:71:65:fe:fd:4f:43
[config properties]# exit

Alternatively, device properties can be set via the Control Center. Log into the Control Center, navigate to the Local Manager in the Inventory, click on the port for the managed device in the Device section of the Local Manager summary page, and click the Properties link in the left navigation bar. The following page appears so device properties can be added or deleted:

Port Properties

Usage¶

Once device properties are configured for a managed device as specified above, the Terminal Application failover feature is configured and active. To use the Terminal Application to access the console port of a managed device, connect to the web interface of the Control Center and navigate to the Inventory page. Select a Local Manager from the Inventory tree to bring up its Summary page. Launch the Terminal Application by clicking the chevron next to the SSH button and selecting the Open native terminal option on the SSH menu. Should the Terminal Application fail to establish an SSH session to the Local Manager, the terminal will then attempt to establish an SSH session directly to the managed device.