Tag Archives: SSH

SSH on Windows 10

Posted by on 2019/08/07 No comments

I remember that they (Microsoft) mentioned the bash shell on Windows 10 a while ago and other Linux/Ubuntu integration stuff but at the time it seemed to be just a gimmick.

But since I’m looking into Nagios and some Windows monitoring I now the need to daily connect to my Nagios server making configuration changes. So far I’ve been using good old Putty/WinSCP and it works well. Then I started looking at a way to generate configurations files for some Windows machines and upload them automatically via PowerShell (or it could end up being another tool created in C# eventually). This is how I stumble across the Windows 10 built in SSH functionality – it’s been there for at least a year! (since build 1803).

That means you can simply use the ssh command in a Windows command shell (or PowerShell) and send commands to your Linux server. To start it simple open a command prompt (cmd.exe) and run ssh:

As can be seen it supports all the basics of any ssh client.

So that cover the basics. The real power comes when you start mixing it with PowerShell and proper scripting and/or batch files.

One very interesting (and incredibly useful) example is something Scott Hanselman posted – how to automatically log into a remote linux machine – see this.

SSH from PowerShell

Posted by on 2016/11/14 No comments

I’ve been playing with more non Microsoft technologies recently and even have a few Linux VMs running here and there. In the process I’ve learned a lot about interacting between the two worlds/environments using technologies like SSH and even running the Powershell Alpha previews on my Linux VMs. Then I got ‘bored’ and looked for a way to programmatically interact with my VMs (for monitoring) and discovered the open source project SSH.Net which I now have incorporated into even QuickMon. Then I got even more bored and started looking for a way to use SSH from Powershell and came across the SSH-Sessions module which incidentally also use SSH.Net to give Powershell a way to call/connect using SSH.

No PassPhrase

This all works nicely except… SSH-Sessions had one shortcoming.. which I just had to fix. The creator(s) of this module implements a way to specify a key file when connecting to an SSH server but does not provide a way to specify the ‘PassPhrase’ at all! WHY?

Any way, I knew the SSH.Net library does support it since I actually make use of this functionality in QuickMon. Then I started digging inside the SSH-Session script files and made a few adjustments…

Fix

To enable PassPhrase functionality I simply had to add the following code in the ‘New-SshSession’ function:

Change the function header to:

function New-SshSession {
    param([Parameter(Mandatory=$true)][string[]] $ComputerName,
          [Parameter(Mandatory=$true)][string]   $Username,
          [string] $KeyFile = '',
          [string] $PassPhrase = 'blankPassphrase',
          [string] $Password = 'SvendsenTechDefault', # I guess allowing for a blank password is "wise"...          
          [int] $Port = 22,
          [switch] $Quiet
    )

and then inside the function:

if ($KeyFile -ne '') {
        if (-not $Quiet) {
            "Key file specified. Will override password. Trying to read key file..."
        }
        if ($PassPhrase -eq 'blankPassphrase') {
            $SecurePassPhrase = Read-Host -AsSecureString "key provided. Please enter pass phrase for $KeyFile"
            $PassPhrase = ConvertFrom-SecureToPlain $SecurePassPhrase
        }
        if (Test-Path -PathType Leaf -Path $Keyfile) {
            $Key = New-Object Renci.SshNet.PrivateKeyFile( $Keyfile, $PassPhrase ) -ErrorAction Stop
        }
        else {
            "Specified keyfile does not exist: '$KeyFile'."
            return
        }   
    }

Example

And with the you can now use the module to connect to SSH using a Key file that has a PassPhrase. If you don’t specify the PassPhrase the script will prompt you for one. If you actually don’t have a PassPhrase at all then pass an empty string as the value of PassPhrase (not tested but it should work).

Import-Module SSH-Sessions
New-SshSession -Computer mySSHServer -Username me  -KeyFile 'c:\mykeys\mykey.key' -PassPhrase 'somePhrase'
Invoke-SshCommand  -ComputerName mySSHServer -Command "cat /proc/cpuinfo | grep processor" -Quiet
Remove-SshSession -RemoveAll -Quiet