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Archive for August 9th, 2021

autossh on Windows from a service: automatically starting a tunnel no matter anyone being logged on

Posted by jpluimers on 2021/08/09

There is an autossh binary for Windows available on GitHub: [WayBack] GitHub – jazzl0ver/autossh: Windows binary for autossh v1.4c.

Combined with NSSM (which for instance you can install through [WayBack] Chocolatey Software | NSSM – the Non-Sucking Service Manager) you can not only automatically build and maintain an SSH connection, but also ensure the autossh process is up and running as a service without the need for an active logon.

This allows for SSH based tunnels from and to your Windows system.

For this usage scenario, there is no need for these tools any more:

Future research:

One time steps

These are in part based on:

1. Download autoSSH

Download the most recent [WayBack] Releases · jazzl0ver/autossh · GitHub  (see below for updates).

I used the 1.4g version: [WayBack] autossh.exe, then put on my Windows PATH.

2. Install NSSM

Since it is on chocolatey ([WayBack] Chocolatey Software | NSSM – the Non-Sucking Service Manager, this will suffice:

choco install --yes nssm

3 .Prepare remote computer so it allows enough SSH retries

Check the value of MaxAuthTries in /etc/ssh/sshd_config.

# grep MaxAuthTries /etc/ssh/sshd_config MaxAuthTries 1

The value needs to be at least 3 or higher for ssh-copy-id to work properly.

When changing the value, be sure to restart the sshd daemon.

Without a low value of MaxAuthTries in /etc/ssh/sshd_config, ssh-copy-id will give an error ERROR: Received disconnect from myRemoteComputer port 2222:2: Too many authentication failures.

See also these link via [WayBack ]“INFO: attempting to log in with the new key(s), to filter out any that are already installed” “Too many authentication failures” – Google Search:

4. Temporarily allow the remote account to perform interctive logon

Temporarily change the user shell to /bin/bash to allow [WayBack] ssh-copy-id to work at all.

This is explained in more detail by [WayBack] shell – ssh dissable login, but allow copy-id – Server Fault.

5. Generate public and private key pairs

You need an ssh public and private key, then transfer this to your Windows client. You can for instance use these as a base:

For instance (where myLocalUser is the local user generate the key-pair for for, and myRemoteUser plus myRemoteComputer is the remote user and computer you want to autossh to):

  • ssh-keygen -t rsa -b 4096 -f %UserProfile%\.ssh\id_rsa_myLocalUser@%ComputerName%_autossh_myRemoteUser@myRemoteComputer
  • ssh-keygen -t ed25519 -f %UserProfile%\.ssh\id_ed25519_myLocalUser@%ComputerName%_autossh_myRemoteUser@myRemoteComputer

6. install git (for ssh-copy-id and bash)

Since git includes ssh-copy-id (which you need in the next step, it is at %Program Files%\Git\usr\bin\ssh-copy-id) and git is on chocolatey ([WayBack] Chocolatey Software | Git (Install) 2.23.0):

choco install --yes git.install --params "/GitAndUnixToolsOnPath /NoGitLfs /SChannel /NoAutoCrlf /WindowsTerminal"

7. Copy the public parts of the generated key pairs to the remote account on the remote machine

Use bash with ssh-copy-id to transfer the generated public keys to a remote system (replace 2222 with the SSH port number on the remote computer; often it is just 22):

pushd %UserProfile%\.ssh
bash -c "ssh-copy-id -i %UserProfile%\.ssh\id_rsa_myLocalUser@%ComputerName%_autossh_myRemoteUser@myRemoteComputer -p 2222 myRemoteUser@myRemoteComputer"
bash -c "ssh-copy-id -i %UserProfile%\.ssh\id_ed25519_myLocalUser_%ComputerName%_autossh_myRemoteUser@myRemoteComputer -p 2222 myRemoteUser@myRemoteComputer"

This sounds overly complicated, but is the only way to incorporate the environment variables.

8. Test with ssh, then with autossh

These two ssh commands should succeed; choose the one for which you prefer the rsa or ed25519 algorithm.

  • ssh -i %UserProfile%\.ssh\id_rsa_myLocalUser@%ComputerName%_autossh_myRemoteUser@myRemoteComputer -p 2222 myRemoteUser@myRemoteComputer
  • ssh -i %UserProfile%\.ssh\id_ed25519_myLocalUser_%ComputerName%_autossh_myRemoteUser@myRemoteComputer -p 2222 myRemoteUser@myRemoteComputer

After this, try with autossh:

  • autossh -M 0 -o "ServerAliveInterval 30" -o "ServerAliveCountMax 3" -i %UserProfile%\.ssh\id_rsa_myLocalUser@%ComputerName%_autossh_myRemoteUser@myRemoteComputer -p 2222 myRemoteUser@myRemoteComputer
  • autossh -M 0 -o "ServerAliveInterval 30" -o "ServerAliveCountMax 3" -i %UserProfile%\.ssh\id_ed25519_myLocalUser_%ComputerName%_autossh_myRemoteUser@myRemoteComputer -p 2222 myRemoteUser@myRemoteComputer

This disables the autossh port monitoring (the -M 0 option, but uses a combination of interval/count-max from ssh itself to monitor the connection (the -o "ServerAliveInterval 30" -o "ServerAliveCountMax 3" options).

Note that there is no default monitoring port, as it can be any one: [WayBack] linux – What is the default monitoring port for autossh? – Super User

9. Install autossh as a service



  1. a
  2. b
  3. c
  4. d
  5. e

SSH logon

Depending on which algorithm you like most, use either of the below 2 (replace 2222 with the SSH port number on the remote computer; often it is just 22):

  • ssh -i %UserProfile%\.ssh\id_rsa_myLocalUser@%ComputerName%_autossh_myRemoteUser@myRemoteComputer -p 2222 myRemoteUser@myRemoteComputer
  • ssh -i %UserProfile%\.ssh\id_ed25519_myLocalUser_%ComputerName%_autossh_myRemoteUser@myRemoteComputer -p 2222 myRemoteUser@myRemoteComputer


C:\Users\jeroenp>ssh-keygen -t ed25519 -f %UserProfile%\.ssh\id_ed25519_myUser_%ComputerName%_autossh_revue
Generating public/private ed25519 key pair.
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in C:\Users\jeroenp\.ssh\id_ed25519_myUser_D10U003_autossh_revue.
Your public key has been saved in C:\Users\jeroenp\.ssh\
The key fingerprint is:
SHA256:6qjzXhQtZpTzU6aryHMYuwVs5b4a/2COKxFGFQj0Eg4 jeroenp@D10U003
The key's randomart image is:
+--[ED25519 256]--+
|E+ oo...         |
|o =  .o.  o      |
| + .  *o.+       |
|  +. = o+        |
| . .+ o So       |
|  ...+ ..        |
|   o.=B.         |
|  o *@oo         |
|  .*O*=..        |

C:\Users\jeroenp>ssh-keygen -t rsa -b 4096 -f %UserProfile%\.ssh\id_rsa_myUser_%ComputerName%_autossh_revue
Generating public/private rsa key pair.
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in C:\Users\jeroenp\.ssh\id_rsa_myUser_D10U003_autossh_revue.
Your public key has been saved in C:\Users\jeroenp\.ssh\
The key fingerprint is:
SHA256:WaWRoAnr4OuXAnc+MekpbdnNto71SgdMykp7XqylQr8 jeroenp@D10U003
The key's randomart image is:
+---[RSA 4096]----+
|    .   .....    |
|     o o  .+     |
|  . . o . o      |
| . o . + o       |
|  . o.o S        |
|. .o*o . .       |
| o.*oO.o* .      |
| .o %ooO+o       |
|  .= oE++o.      |


NSSM is really cool to run any application as a service: [WayBack] NSSM – the Non-Sucking Service Manager

nssm is a service helper which doesn’t suck. srvany and other service helper programs suck because they don’t handle failure of the application running as a service. If you use such a program you may see a service listed as started when in fact the application has died. nssm monitors the running service and will restart it if it dies. With nssm you know that if a service says it’s running, it really is. Alternatively, if your application is well-behaved you can configure nssm to absolve all responsibility for restarting it and let Windows take care of recovery actions.

nssm logs its progress to the system Event Log so you can get some idea of why an application isn’t behaving as it should.

nssm also features a graphical service installation and removal facility. Prior to version 2.19 it did suck. Now it’s quite a bit better.

After installing, everything is command-line based (I cut away some blank lines for readability):

C:\bin\bin>nssm --help
NSSM: The non-sucking service manager
Version 2.24-101-g897c7ad 64-bit, 2017-04-26
Usage: nssm [ ...]

To show service installation GUI:

        nssm install []

To install a service without confirmation:

        nssm install   [ ...]

To show service editing GUI:

        nssm edit 

To retrieve or edit service parameters directly:

        nssm dump 
        nssm get   []
        nssm set   [] 
        nssm reset   []

To show service removal GUI:

        nssm remove []

To remove a service without confirmation:

        nssm remove  confirm

To manage a service:

        nssm start 
        nssm stop 
        nssm restart 
        nssm status 
        nssm statuscode 
        nssm rotate 
        nssm processes 

Windows binary autossh version

If it is behind on [WayBack] autossh (see version history at [WayBack] autossh/CHANGES.txt), then just ask for a new version; usually it gets built and released quickly: [WayBack] Any plans for 1.4g? · Issue #3 · jazzl0ver/autossh · GitHub

[WayBack] Releases · jazzl0ver/autossh · GitHub  at the time of writing:


Posted in *nix, *nix-tools, Communications Development, Development, Internet protocol suite, Power User, SSH, TCP | Leave a Comment »

It looks like a volunteer has been found to maintain the openvpn chocolatey

Posted by jpluimers on 2021/08/09

The chocolatey package for OpenVPN has not been updated for quite a while. It looks like it has to do with the current dependency to verify the OpenVPN signature.

The current [Wayback] Chocolatey Software | OpenVPN 2.4.7 version is both outdated on the major version number ([Wayback/] Release OpenVPN v2.5.3 release · OpenVPN/openvpn) and minor version ([Wayback/] Release OpenVPN v2.4.11 release · OpenVPN/openvpn). The version 2.4 Windows installers are now called “Legacy Windows Installers”.

Luckily less than a day after the start of the [Wayback/] RFM – openvpn · Issue #1024 · chocolatey-community/chocolatey-package-requests, a volunteer stepped forward.

Hopefully by now the package is being maintained again.


Posted in Network-and-equipment, OpenVPN, Power User, VPN | Leave a Comment »

How to turn on automatic logon in Windows

Posted by jpluimers on 2021/08/09

[WayBack] How to turn on automatic logon in Windows

Describes how to turn on the automatic logon feature in Windows by editing the registry.

Most archivals of the above post fail with a 404-error after briefly flashing the content, but this particular one usually succeeds displaying.

It is slightly different from the one referenced in my blog post automatic logon in Windows 2003, and because of the archival issues, I have quoted most of it below.

A few observations, at least in Windows 10 and 8.1:

  • Major Windows 10 upgrades will disable the autologon: after each major upgrade, you have to re-apply the registry patches.
  • If the user has a blank password, you can remove the DefaultPassword value.
    • Empty passwords allow local logon (no network logon or remote desktop logon), no network access and no RunAs, which can actually help improve security. More on that in a later blog post
  • For a local machine logon, you do not need the DefaultDomainName value either (despite many posts insisting you need them), but you can technically set it to the computer name using reg add "HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Winlogon" /v DefaultDomainName /t REG_SZ /d %ComputerName% /f
  • If another user logs on and off, the values keep preserved, so after a reboot, the correct user automatically logs on
  • you need a full reboot cycle for this to take effect
  • The AutoLogon tool does not allow blank passwords

I wrote a batch file enable-autologon-for-user-parameter.bat that makes it easier:

if [%1] == [] goto :help

  reg add "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon" /v AutoAdminLogon /t REG_SZ /d 1 /f
  reg add "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon" /v DefaultUserName /t REG_SZ /d %1 /f
  reg delete "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon" /v DefaultPassword /f
if [%2] == [] goto :eof
  reg add "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon" /v DefaultPassword /t REG_SZ /d %2 /f  
  goto :eof

  echo Syntax:
  echo   %0 username password

The article quote:

Read the rest of this entry »

Posted in Batch-Files, Development, Microsoft Surface on Windows 7, Power User, Scripting, Software Development, Windows, Windows 10, Windows 7, Windows 8, Windows 8.1, Windows 9, Windows Server 2003, Windows Server 2003 R2, Windows Server 2008, Windows Server 2008 R2, Windows Server 2012, Windows Server 2012 R2, Windows Server 2016, Windows Vista, Windows XP | Leave a Comment »

Windows 8.x: CPUs vs CPU cores matters!

Posted by jpluimers on 2021/08/09

After finding out that Windows 8.1 only uses 2 of of 3 CPU cores, I found [WayBack] How many physical processors does Windows 8 Support? – Super User.

This especially matters when doing virtualisation: here you can choose over how many CPU sockets the cores are divided.

So this limits Windows 8.x to 2 CPU cores, because they 3 cores are spread over 3 sockets:

And this allows Windows 8.x to use 3 CPU cores as it is in one socket:

Note this still applies to more recent non-Server Microsoft products ([Wayback] Windows 10 Home/Pro: 1/2 CPU sockets 64/128 cores; [Wayback] SQL Server Express/Standard: lesser of 1/4 CPU sockets, 4/24 cores) as well. Not sure why the OS would be limited so much, as for development purposes it can make sense to have a 2+ CPU socket machine running a non-server OS.


Posted in Power User, Windows, Windows 8, Windows 8.1 | Leave a Comment »

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