SSH Terminal
An interactive shell on a monitored node, opened from the node menu in either console. The session is carried by the probe that monitors the node, so a device on an isolated network is reachable without a separate jump host.
Node menu Tools SSH Terminal
Monitoring tells you a Linux host is out of disk space; the next step is almost always a shell on it. SSH Terminal opens one against the node you are already looking at, without leaving the console and without a separate SSH client.
It is a full interactive session, not a command runner. There is no scheduling and no output capture — for commands that should run unattended see Scripting Sensors, and for putting your own local utilities on the node menu see Custom Node Tools.
Where the Session Runs
The session is opened by the monitoring probe responsible for the node. It is not opened by your browser and not by the machine running the console. Where the node is monitored by the NetCrunch Server itself, the server opens it.
One consequence is worth knowing: the reachability that matters is the probe's, not yours. If the probe can reach the device the terminal works — including when the device sits in an isolated network your workstation has no route to. A device the probe cannot reach will not open, however well you can reach it yourself.
The connection is made to the node's address on port 22. The port is fixed, so a device listening for SSH on a different port cannot be reached this way.
The shell lives on the probe for as long as the session is open. Closing the terminal window ends it, and so does closing or reloading the console page — the session is canceled and the shell on the device closes with it.
Who Can Open It
Opening a shell on a device is an administrative action, and NetCrunch treats it as one:
- a NetCrunch administrator can open the terminal on any node
- any other user needs the Administrator access right on that particular node
Read-only or restricted access is not enough. The menu entry is hidden for users who do not qualify, and the page checks the right again when it loads, so opening its URL directly does not get round it. A user without the right sees Access denied.
The entry is offered for ordinary IP nodes only, and is not available in the Mobile Console.
Secure Connection Required
In the Web Console the terminal opens only when the console is served over HTTPS, or when it is being used on the server itself through localhost or 127.0.0.1. Over plain HTTP the action reports Not available due lack of secure connection and refuses.
Credentials and keystrokes travel over the browser connection, and NetCrunch will not carry them over an unencrypted one. If you intend to use SSH Terminal, install a certificate for the web server — see NetCrunch Security Features.
The Desktop Console hosts the same page in its own window and is not affected.
Choosing Credentials
Every session begins at a login panel offering three sources.
- Node
- The node's own monitoring credentials — the Linux, BSD, macOS or Solaris monitor already configured for it. This is the default, and usually the right answer.
- Profile
- A named credential profile. The list holds profiles of the four SSH families: Linux, BSD, macOS and Solaris. Windows profiles are deliberately absent, because Windows monitoring credentials are not SSH credentials.
- Enter
- A username and password typed for this session only. Nothing is saved.
Only typed credentials leave the browser. Choose the node's own credentials or a named profile and only the reference travels — the password is resolved where the session is opened and never reaches the browser at all. Prefer a profile over typing whenever one exists.
A refused login returns you to the panel with the reason, keeping the username so that only the password has to be typed again.
Using the Terminal
The terminal is a full VT-compatible emulator.
- It sizes itself to the window and tells the remote pty the new geometry, so full-screen programs such as
top,lessandvidraw correctly. Resizing the window during a session resizes the shell with it. - Right-click copies the selection when there is one, and pastes when there is not.
- Ctrl+C copies when text is selected, and is passed to the shell as an interrupt when nothing is selected.
- Ctrl+V pastes.
Type exit, or end the shell any other way, and the window closes with it.
When It Does Not Open
- Access denied
- You do not hold the Administrator access right on this node.
- Could not open the SSH session
- The session ended before the shell produced any output. The usual causes are a rejected password, SSH not listening on the device, or the device refusing the connection.
- No answer from the probe - the session was not started
- The request to open was not answered within 15 seconds. Check that the probe is connected and not overloaded.
- Not available due lack of secure connection
- The Web Console is being used over plain HTTP. See above.
- Distributed Monitoring
Learn about monitoring probes that expand on-premises monitoring into distributed environments across multiple sites and address spaces
- Probe Offline Monitoring Mode
A monitoring probe can keep monitoring while it is disconnected from the NetCrunch Server, buffering results locally and synchronizing them once the connection returns.
- Site Monitoring Modes
A site with more than one monitoring probe can either assign nodes to probes explicitly, or spread the monitoring load across all of its probes automatically.
- Custom Node Tools
Add your own commands to the node menu in the Desktop Console, so the tools you already use on a device are one click away from the node representing it.