Archive

Posts Tagged ‘ssh’

Using plink to modify ESXi host configuration files via SSH from a PowerCLI script

December 17th, 2012 10 comments

I am a big advocate of automation and saving time with a good script. Whenever I can find a task that is fairly lengthy, and is likely to be repeated in future, I always consider scripting it. There are many way to configure an ESXi host when it comes to writing build or automation scripts. In fact, I often feel we are quite spoilt for choice. Here are just some of the tools we have available to use:

  • PowerCLI
  • esxcli
  • vMA
  • vCLI

I was working on a build configuration script the other day using PowerCLI and found the need to edit some configuration files on the hosts. I wanted to edit the configuration file /etc/vmware/config during the execution of a single PowerCLI script without needing to stop the script or have an additional step to do myself. The following is what I came up with to achieve this:

  • Configure host as normal using PowerCLI
  • Use PowerCLI to start SSH service on host
  • execute plink script to connect to host, run command via SSH, then disconnect
  • Use PowerCLI to stop SSH service on host
  • Continue with rest of PowerCLI script

 

Plink is a command line connection tool – essentially a command line version of PuTTy. You can call it from dos prompt and issue it with a single, (or list) of commands to run once connected to a specified host. You can download Plink over here.

 

So without further ado, let’s take a look at the script as I described above.

# At start of our script we ask for the host's IP or name (this could be automated if you like)
$hostIP = Read-Host "Enter ESX host IP/dns name: "
$vmhost = Get-VMHost $hostIP

# Start the SSH service
$sshService = Get-VmHostService -VMHost $vmhost | Where { $_.Key -eq “TSM-SSH”}
Start-VMHostService -HostService $sshService -Confirm:$false

# Use SSH / plink to configure host with some additional script
cmd /c "plink.exe -ssh -pw HOSTROOTPASSWORD -noagent -m commands.txt root@$hostIP"

# Stop SSH service
Stop-VMHostService -HostService $sshService -Confirm:$false

 

As you can see, we start off by asking for the host IP or name, this is the only bit of manual input, but even this could be automated. The script then finds the SSH service on the host, and starts it. After this, the script calls the plink.exe file via cmd /c and connects using the root user@ the host’s IP as we entered at the beginning of the script over SSH. Plink is pointed to a commands.txt file (previously placed in the script execution folder), which contains the actual lines of bash script to be executed on the ESXi host via SSH.

Here is the content of the commands.txt file that I refer plink.exe to use (as an example, this bit of script enables copy/paste operations on all VMs running on this host in the guest OS’ console, as per VMware KB 1026437), but could contain any other commands you wish to execute on the ESXi host over SSH.

echo 'isolation.tools.copy.disable="FALSE"' >> /etc/vmware/config
echo 'isolation.tools.paste.disable="FALSE"' >> /etc/vmware/config

 

* Note two very useful techniques show by Alan in the comments section below, showing how to automatically download plink.exe if it is not available when the script is run, and also how to accept the SSH fingerprint key request by piping Y to plink.exe via the script – check out Alan’s blog post here for more detail.

How to use PoSH or PowerCLI to SSH into network devices – wodSSH [Part 2]

March 26th, 2012 2 comments

 

In [part 1] of this series of posts, I explored SharpSSH, and how to use this to SSH into network devices via PowerShell or PowerCLI. I found this extremely useful, and managed to automate a process of retrieving some SHA1 SSL fingerprints from a few clusters of ESX hosts in the process. I did however find that loading the dll and functions necessary to get this bit of automation done was a little tedious. I had heard about wodSSH via the get-scripting podcast and decided I would need to take a look at this.

 

If you are planning on using wodSSH, you should start by downloading it here. Note that you should definitely buy a license if you are going to be using this for your job or day to day automation – the license is not to expensive if you consider the kinds of automation you could achieve with this! For this blog post I am just using the trial version in my lab environment at home to try out – the trial pops up a “nag screen” every now and then to indicate you are unlicensed. Once downloaded, install wodSSH and the libraries will now be available for use on your machine.

 

Download the script below, or take a look at it in the Syntax Highlighted area below – this is an example of how I was able to SSH into a cluster of ESXi hosts and run a remote command via SSH through PowerCLI. In this example, a table is returned with Host names, along with their SHA1 fingerprint information. It is possible to retrieve this info (as of ESXi 5 I believe) in PowerCLI, but for this example I just wanted to demonstrate the use of SSH and PowerShell / PowerCLI.

 

Download wodSSH PowerCLI Implementation Script (749)

 

$login = "root"
$password = "yourrootpassword" 

$Report = @()
$VMHosts = Get-VMHost | Where {$_.ConnectionState -eq "Connected"} | Sort Name

foreach ($vmhost in $VMHosts) {
	$hostname = $vmhost
	$ssh = New-Object -ComObject "weOnlyDo.wodSSHCom.1"
	$ssh.Hostname = $hostname
	$ssh.Login = $login
	$ssh.Password = $password
	$ssh.Blocking = 1
	$ssh.Protocol = 4
	$ssh.Timeout = 25
	$ssh.Connect($hostname)
	$ssh.WaitFor("regex:[$%#>] $")
	$cmdresult = $ssh.Execute("openssl x509 -sha1 -in /etc/vmware/ssl/rui.crt -noout -fingerprint`r`n","regex:[~#]")
	$ssh.Disconnect()
	$temp = $cmdresult | select-string -pattern "SHA1 Fingerprint="
	Write-Host $cmdresult -ForegroundColor Green
	$row = New-Object -TypeName PSObject -Property @{
		SHA1 = $cmdresult
		HostName = $vmhost
	}
	$Report += $row
}
$Report

 

You will notice that on line 09, we load the wodSSH library using the New-Object cmdlet. After this we continue to setup some properties for our $ssh connection object. A regex check is used to determine when are connected to a host and have an SSH shell prompt ($ssh.WaitFor(“regex:[$%>;] $”).  We then use $cmdresult to capture the result of running an SSH command via our connection to our current ESXi host. To finish capturing the output of the command on our remote host, we use a regex check again (“regex:[~#]”). You’ll notice that the actual command is also on this line, i.e. line 18 (openssl). After the result is captured, we disconnect our SSH session, then proceed to build our small report array. At the end of the script, we output the $Report array to the screen.

 

Results of the above script in PowerCLI

 

As far as I can see, the wodSSH library can open up a whole new world of automation for you in the data centre. Think of the possibilities – you could automate just about everything, from switches, routers, Linux/Unix hosts / ESXi Hosts to iLO / DRAC and other management cards. Essentially, anything that accepts commands via SSH! If you have any automation stories using wodSSH, or just PowerShell or PowerCLI in general, I would love to hear about them – so feel free to drop a comment or two on this post.

 

 

How to use PoSH or PowerCLI to SSH into Devices & retrieve information (Gathering SHA1 Fingerprints)

March 15th, 2012 No comments

 

I was listening to GetScripting podcast #29 the other day. The guest was Pete Rossi (PoSH Pete), and in the discussion he discussed data centre automation. Part of the automation he has set up involves wrapping SSH with PowerShell, and by doing so he is able to automate various functions on devices that can be SSH’d onto. This got me thinking of potential use cases. Soon enough I already had a couple of use case scenarios that could do with automating using SSH and PowerCLI. Pete mentioned he mainly uses an SSH component by a company called “WeOnlyDo Software”, however Alan Renouf also mentioned having heard of “SharpSSH”. I decided I wanted to try both out and figure out how to use both, so with that I set out figuring out how to get them working with PowerShell and PowerCLI. In this post (Part 1) I will cover using the SharpSSH DLL. In Part 2 I will go into the (easier in my opinion) wodSSH component (also paid for) method.

 

SharpSSH (based on Tamir Gal’s .NET library)

 

I believe Tamir Gal originally created this library, however it seems to now be maintained by others.

 

First of all, for SharpSSH to work with PowerShell or PowerCLI, you’ll need to get the relevant DLL that will be loaded by your script. I found a version of SharpSSH being actively worked on and improved by Matt Wagner on Bitbucket. I downloaded this version (called SharpSSH.a7de40d119c7.dll) to get started. To load the functions that we’ll be using to SSH in to devices, I used the following PowerShell function. Just be sure to reference in the correct path of the SharpSSH DLL that you downloaded above in this function. Download the function below:

 

Download SharpSSH Functions (883)

 

Then as long as the functions are loaded in your PoSH session, you should be able to run the example below.

 

How to SSH into ESXi hosts and retrieve SHA1 Fingerprints using PowerCLI and SharpSSH

 

Example output after running the script detailed below against multiple ESX hosts

 

 

Now, first off I’ll say that this isn’t necessarily the best way of retrieving SSL Fingerprints from your ESXi hosts in terms of security – you’d want to do this from the DCUI of the ESXi hosts to confirm the identity of each host is as you expect. (See this blog post and comments over at Scott Lowe’s blog for more detail on the security considerations). With that being said, here is my implementation of SharpSSH, used to SSH into each ESXi host (from a Get-VMHost call) and retrieve the SHA1 Fingerprints. The script will create and output a table report, listing each ESX/ESXi host as well as their SHA1 Fingerprint signatures.

 

Background for the Script

 

I believe this is actually quite an easy bit of info to collect using PowerCLI and the ExtensionData.Config properties on newer hosts / vSphere 5, but in my environment I was working with, all my ESX 4.0 update 4 hosts did not contain this Fingerprint info in their ExtensionData sections when queried with PowerCLI. Therefore I automated the process using SSH as I could use the command “openssl x509 -sha1 -in /etc/vmware/ssl/rui.crt -noout -fingerprint” to generate the Fingerprint remotely on each host via SSH. So with that in mind, here is the script that fetches this info. Note it will prompt for root credentials on each host that is connected to – this could probably be easily changed in the Function (downloaded from above). So here is the final script which will list all ESXi hosts and their SHA1 Fingerprints:

 

$Report = @()
$VMHosts = Get-VMHost | Sort Name

foreach ($vmhost in $VMHosts) {
	New-SshSession root $vmhost
	if (Receive-SSH '#')
	{
		Write-Host "Logged in as root." -ForegroundColor Green
		$a = Invoke-SSH "openssl x509 -sha1 -in /etc/vmware/ssl/rui.crt -noout -fingerprint" 'SHA1'
		$temp = $a | select-string -pattern "SHA1 Fingerprint="
		$row = New-Object -TypeName PSObject -Property @{
			SHA1 = $temp
			HostName = $vmhost
		}
		$Report += $row
		$rootlogin = $true
		Write-Host "Output complete." -ForegroundColor Green
	}
	if ($rootlogin -eq $true)
	{
		Write-Host "Exiting SSH session."
		Send-SSH exit
	}
	Write-Host "Terminating Session."
	Remove-SshSession
}

$Report

 

Well, I hope this helps you out with a way to automate SSH access to devices to retrieve information or change settings. This could easily be adapted to send SSH commands to any other kind of device that accepts SSH as a method of login. Switches, Routers, linux servers, you name it! In my next blog post I will be showing you how to use the wodSSH library (We Only Do Software) to do SSH in PowerShell or PowerCLI – I have found this method to be a bit easier to use when compared with SharpSSH! So look out for my next post coming soon!

Change iPhone root SSH password

November 30th, 2009 No comments

If you have jailbroken your iPhone and have SSH installed it is a very good idea to change your default root password. The default root password for the iPhone 3G is “alpine” many people know this and if you are not careful you could get someone gaining access to your phone over your service providers’ data network or over a local wifi connection.

iphone-ssh

Once SSH is installed and active login to your phone using PuTTY.  Download PuTTy here.

You will just need to specify your phone’s local wifi IP address and SSH as the connection method. When prompted, enter your username as : root and password as : alpine

Once you get a command line, type in the command “passwd” and press enter.

Enter your existing password of alpine, then specify your new root password. Be sure to keep this safe and secure! I found that after changing the root password on my phone I needed to restart it – close putty, then restart your iPhone.

Categories: apple, Linux / uBuntu Tags: , , , ,

allowing root SSH access to your ESX host

April 21st, 2009 No comments

In order to be able to SSH into your ESX host server via putty you need to enable root access via SSH. By default this is disabled – we will modify a configuration file and restart the service to allow ourselves into the ESX host console remotely.

From the console (you will need to physically be at the machine, or at least via a DRAC or KVM over IP), press Alt-F1 to access the command line and login as root.

Edit the following file:

/etc/ssh/sshd_config

You can do this by typing:

nano /etc/ssh/sshd_config

Go to the line that reads “PermitRootLogin no”

and change this to read “PermitRootLogin yes”

Press Ctrl-X to exit and press the “Y” key, hitting Enter to commit the choice to save.

Now we need to restart the sshd service to enable the changes. Type:

service sshd restart

and press enter.

You will now be able to SSH in as root.

Please drop me a comment if this has helped in any way!