Zhixian's Tech Blog


Using ACMESharp to get SSL certificates from Let’s Encrypt

This blog post is a reminder note to myself on how to use the ACMESharp PowerShell module to get SSL certificates from Let’s Encrypt CA.

Essentially, the usage can be divided into the following phases:

  1. Install ACMESharp PowerShell module
  2. Import ACMESharp PowerShell module
  3. Initial (one-time) setup
  4. Register DNS of certificate
  5. Get "challenge" details (to prove that you are the owner of the domain)
  6. Signal Let’s Encrypt to confirm your challenge answer
  7. Download certificates

Steps 1-3 is only for setting up on a new PC.
Step 2, 4 should be repeated for each domain that you want SSL certificates for.
Steps 2, 5-7 should be repeated whenever you want to get or renew certificate.

1. Install ACMESharp PowerShell module

Install-Module -Name ACMESharp -AllowClobber

2. Import ACMESharp PowerShell module

Import-Module ACMESharp

3. Initial (one-time) setup


New-ACMERegistration -Contacts mailto:zhixian@hotmail.com -AcceptTos

4.  Register DNS of certificate

New-ACMEIdentifier -Dns plato.emptool.com -Alias plato_dns

5. Get challenge (to prove that you are the owner of the domain)

Complete-ACMEChallenge plato_dns -ChallengeType http-01 -Handler manual

6. Signal Let’s Encrypt to confirm your challenge answer

Submit-ACMEChallenge plato_dns -ChallengeType http-01
(Update-ACMEIdentifier plato_dns -ChallengeType http-01).Challenges | Where-Object {$_.Type -eq "http-01"}
New-ACMECertificate plato_dns -Generate -Alias plato_cert1
Submit-ACMECertificate plato_cert1
Update-ACMECertificate plato_cert1

7. Download certificates


Get-ACMECertificate plato_cert1 -ExportCertificatePEM "C:\src\certs\plato_cert1.crt.pem"
Get-ACMECertificate plato_cert1 -ExportIssuerPEM "C:\src\certs\plato_cert1-issuer.crt.pem"

Add-Content -Value (Get-Content plato_cert1.crt.pem) -Path nginx.plato.emptool.com.pem
Add-Content -Value (Get-Content plato_cert1-issuer.crt.pem) -Path nginx.plato.emptool.com.pem


ZX: Generating SSL certificates for HAPROXY is similar to NGINX, except it includes a key.

Get-ACMECertificate plato_cert1 -ExportKeyPEM "C:\src\certs\plato_cert1.key.pem"
Get-ACMECertificate plato_cert1 -ExportCertificatePEM "C:\src\certs\plato_cert1.crt.pem"
Get-ACMECertificate plato_cert1 -ExportIssuerPEM "C:\src\certs\plato_cert1-issuer.crt.pem"

Add-Content -Value (Get-Content plato_cert1.crt.pem) -Path haproxy.plato.emptool.com.pem
Add-Content -Value (Get-Content plato_cert1-issuer.crt.pem) -Path haproxy.plato.emptool.com.pem
Add-Content -Value (Get-Content plato_cert1.key.pem) -Path haproxy.plato.emptool.com.pem


Get-ACMECertificate plato_cert1 -ExportPkcs12 "C:\src\certs\iis.plato_cert1.pfx"


How to deploy files to Windows using SFTP via Gitlab pipelines


This blog post describes how you would deploy files to a Windows Server via SFTP using Gitlab pipelines using shared runners.

The practical uptake for this is that you can deploy files for your website to be served by Internet Information Services (IIS) server using Gitlab pipelines.

Note: The context of this post is about deploying websites but the steps described can be used for deploying any type of file using Gitlab pipelines.


  1. Assumptions
  2. What are Gitlab pipelines
  3. How Gitlab pipelines work
  4. Sample .gitlab-ci.yml


  1. You have an working Gitlab account.
  2. You have a working Gitlab repository.
  3. You have a Windows Server
  4. You have a SFTP server running on your Windows Server and you have a working SFTP account for that server.

If you do not have a SFTP server, you can consider SFTP/SCP Server from SolarWinds.
Its not a fantastic product but it would have to do (considering that it is a free product)
The software is available at the following url after registration:

What are Gitlab pipelines

To put it simply, pipelines is Gitlab’s mechanism to perform tasks specified by you when you check-in files into your Gitlab repository. These tasks are executed by processes (dubbed "runners" in Gitlab terminology).

The runners can be grouped in shared and private (non-shared) runners.

Shared runners are hosted by Gitlab to be used by all users of Gitlab that wishes to use them). They are free to use but are limited to 2000 CI minutes per month unless you upgrade your Gitlab plan.

In comparison, private runners are setup using your own resources. After you setup your private runner, you have to register it to Gitlab in order to have Gitlab to use it.

How Gitlab pipelines work

When you check in files into your Gitlab repository, Gitlab will check for the existence of a file called ".gitlab-cl.yml". This file must be named exactly as typed (it is case-sensitive). The existence of this file tells Gitlab that there are tasks to be done. This file will list out the "jobs" for Gitlab to carry out.

Side note: As can be guessed from the file extension ".yml", this is a YAML (YAML Ain’t Markup Language) file. For details for the syntax of YAML, see http://www.yaml.org/

Sample .gitlab-ci.yml

As mentioned in the summary of this blog post, we want to setup a Gitlab pipeline that deploy to our SFTP server whenever we checked in a file. As such the below is the ".gitlab-ci.yml" file that would allow us to do that.

image: alpine

– apk update
– apk add openssh sshpass lftp

stage: deploy
– ls -al
– mkdir .public
– cp -r * .public
– echo "pwd" | sshpass -p $SFTP_PASSWORD sftp -o StrictHostKeyChecking=no zhixian@servername.somedomain.com
– lftp -e "mirror -R .public/ /test" -u zhixian,$SFTP_PASSWORD sftp://servername.somedomain.com
– .public
– master

The following is what what each of lines do:

Line 1: Declare that "jobs" will be executed in a Docker container that use the image "alpine". The "alpine" image used here is one of the lightest Linux container, Alpine Linux. You can use other images as long as that image is in Docker store.

Line 3: The "before_script" section. Declare the actions to be carried before any jobs are executed in this section.

Line 4: Update the Alpine Linux software package manager, "apk". By default, "apk" is empty. So we need to populate it with the software catalog.

Line 5: Install the "openssh", "sshpass" and "lftp" software packages.

Line 7: Our declaration of a job call "deploy_pages"

Line 8: Indicate that this job is only to be execute in the "deploy" stage.

Quick concept of "stage": Basically, a job are executed in different stages in the order of "build", "test", and "deploy". Jobs in the same stage are executed concurrently (assuming there are sufficient runners to execute the jobs).

Line 9: The "script" section. Actions to be carried for the job are specify under here.

Line 10: List files in the docker container entry point. By default, Gitlab will dump a copy of your code repository at the container entry point. I like to see a list of the files. This is otherwise a frivolous step that is not need.

Lines 11 and 12: Make a directory call ".public" (note the period in front of "public") and copy all files at the entry point into this directory.

ZX: This step is for facilitating lftp at step 14. The problem is that Gitlab will dump a copy of the git repository at the entry point as well. But we don’t want to accidentally deploy the git repository, hence the copying of files to a sub-directory.

Line 13: Start a SFTP session to "servername.somedomain.com" using the account name "zhixian" using password stored in secret variable "$SFTP_PASSWORD".
Execute a SFTP command "pwd" and terminate the SFTP session.

ZX: This step seems frivolous, but is essential to the success of this job.
As mentioned, jobs are executed in a Docker container environment.
Hence, if we initiate any form of connection to a new SSH-based environment, system will prompt us to accept the "fingerprint-key" for that new SSH-based environment.
This line creates SFTP connection and accepts "fingerprint-key" for the SSH-based environment without prompts.

ZX: Note the "$SFTP_PASSWORD". This is a secret variable set under your Gitlab repository "Settings" section, under "Pipelines" subsection.


If you scroll down, you will see a "Secret variables" section like the below. The password to the SFTP account is specified here.


Line 14: Executes the "lftp" command. Here, we use the "mirror" feature of lftp. This feature makes a replica of the file structure of the source to the destination.

ZX: Note the "sftp://" prefix in front of the server domain name ("servername.somedomain.com"). It is important to include this to establish SFTP connectivity. If this is not specified, lftp will assume normal FTP.

Line 15: Specify the "artifacts" section. Items listed under the "artifacts" section will be available for download after the job is completed.

Line 16: Specify the "paths" section for the artifacts.

Line 17: Specify that ".public" folder is to be treated as a an artifact made available for download.

Line 18: Specify the branch of code that will cause this job would be executed.

Line 19: Specify the this job is to be executed only when someone checked-in to the "master" branch.

That’s basically all that is needed to get Gitlab to send files to your SFTP server.


Configuration of your jobs with .gitlab-ci.yml (https://docs.gitlab.com/ee/ci/yaml/)


Cannot pull images from docker.io

Filed under: docker — Tags: , , , — Zhixian @ 18:14:09 pm


  1. You are unable to download docker images from the repository.
  2. You received a network timed out error message.
  3. This issue is probably due to your Docker DNS Server setting. Switch it from Automatic to Fixed to resolve issue.


If you just installed docker in Windows (in my case, it is Windows 10 Pro), you may encounter the following error message when trying to pull a docker image from docker.io:

C:\VMs\Docker>docker pull hello-world
Using default tag: latest
Pulling repository docker.io/library/hello-world
Network timed out while trying to connect to https://index.docker.io/v1/repositories/library/hello-world/images. You may want to check your internet connection or if you are behind a proxy.


However, when you open up your browser to navigate to the url (https://index.docker.io/v1/repositories/library/hello-world/images) of the image, you found that you have no problems.


This maybe due to an issue with the Network settings of Docker.
Specifically, the problem maybe with the DNS Server setting.
The DNS Server is set to Automatic by default and that DNS server may not be able to find the docker image repository.


To resolve this issue, simply set the DNS Server setting to “Fixed”.
For the IP address of the DNS Server, you can probably accept the default of “” (which points Google’s DNS server)
After clicking on the “Fixed” radio button, click on the “Apply” button to apply your changes.
This will cause Docker to restart.


After Docker have restarted, you should find that you are able to pull docker images without any issues.



Fixing “The Parallel port driver service failed to start” on Windows 2003

Filed under: computing, windows — Tags: , — Zhixian @ 19:42:01 pm

My first blog post for 2016.
This is a reminder blog post.


  1. Symptoms
  2. Solution
  3. Reference


When your Windows 2003 boot up, you may see another a message like the below:


When you logged into Windows and examine the Event Viewer, you may see an error under System.


When you open up the error, you would see, the following error message:




Start a Windows command prompt and run the following command:

sc config parport start= disabled

Note the space after “start=” in the above command. It is required.

After you ran this command, you should not see the error message prompt on your next Windows bootup.
Note: This solution deviate from the one stated in the reference.



  1. Error message on a Windows Vista-based or Windows Server 2008-based computer that does not have a parallel port: "The Parallel port driver service failed to start"


Minix3 Basic Software Sets

Filed under: computing, minix3 — Zhixian @ 17:49:11 pm

This is done by executing the following commands at the command line:

# pkgin update
# pkgin_sets

When executing pkgin_sets, it will show the following screen and prompt you to install each set one by one.

Zhixian’s note: The software installed can be found in /usr/pkg/bin (or /usr/pkg/sbin for system executables).

First prompt installs:

  1. openssh
  2. vim (exception from the above note; executable is found at /usr/bin/vi)
  3. curl

Second prompt install:

  1. git-base
  2. bmake
  3. gmake
  4. binutils
  5. clang

Third prompt installs:

  1. bison
  2. groff
  3. perl
  4. python (the executable for python is named “python2.7” instead of “python” as found in other installations.)

First Prompt:image


Second Prompt:image


Third Prompt:

For some reason the tiff library is missing from repository.


Installation complete:image


Searching and installing the tiff library that got missed out earlier.


Minix3 Basic Post Installation Setup

Filed under: Uncategorized — Zhixian @ 17:00:11 pm


  1. Set password for root account
  2. Set timezone
  3. Set hostname


Set Password for root account

By default, there is no password assigned for the root account.
You can set a password for root account using the following command:

# passwd


Set timezone

Before you can set the timezone, you need to identify it using the computer standards.
Look at a file /usr/share/zoneinfo for a list of timezone.


In my case, my country Singapore is located in Asia


So my timezone is determined to be Asia/Singapore.
To set the timezone, enter the follow command:

# echo export TZ=Asia/Singapore > /etc/rc.timezone


This will take effect when I log in again.


Set hostname

The default hostname can be rather non-descriptive.


So you might want to change that.
So for example, I chose the hostname of rocket, I would enter the following command to set it:

# hostname rocket


Zhixian’s note: This change does not seem to persist after a reboot. Sad smile
Still exploring how to do this correctly.
The best solution I saw so far is from http://osdir.com/ml/minix3/2011-12/msg00072.html
It suggests putting your IP and host name into /etc/hosts file.
Here’s the excerpt pertaining to problem and suggested solution:image

In case you are wondering, here’s what my /etc/hosts file look like:




MINIX3 Installation

Filed under: computing, minix3 — Tags: , , — Zhixian @ 16:32:11 pm

A list of screen dumps that I taken while installing Minix3 on VirtualBox.
Dumping the screens first. I intend to annotate them at a later date.




































End of installation


Installing Alpine

Filed under: Uncategorized — Zhixian @ 23:08:10 pm

I do not find the default “mail” program in Linux is not user-friendly.

Hence, I would suggest another console e-mail application.
Two applications come to mind, pine and elm.
I’m picking pine as I have slightly more familiarity with it and I think it is more user-friendly than elm.

Pine is a proprietary application owned by University of Washington. So I am picking to install the open-source version of this application call Alpine. To install Alpine type the following command:

$ sudo apt-get install alpine

After the installation has complete, type the following command to run it:

$ alpine

Changing Screen Resolution of Ubuntu on VirtualBox

Filed under: Uncategorized — Zhixian @ 23:08:10 pm

Identify the resolution that your VirtualBox environment supports.

Reboot the system and hit ‘c’ when the grub windows appears appears to access grub console. In grub console, enter the following command to see a list of resolutions (eg, 1024x768x32):

grub> vbeinfo

Edit the grub configuration file
/etc/default/grub. Uncomment the following line in the file.


Replace the resolution with the one appropriate for your environment.

Save the file. Then update your grub configuration by running:

$ update-grub

Restart your virtual machine again




Filed under: Uncategorized — Zhixian @ 23:06:10 pm

This blog is about creating a first Rails web application.
Before proceeding, you need to install sqlite.

Summary of Steps

  1. Install sqlite
  2. Install nodejs
  3. Create hellorails
  4. Running hellorails

Install sqlite

To install sqlite, run the follow commands:

$ sudo apt-get install sqlite3
$ sudo apt-get install libsqlite3-dev

Note: We have to install libsqlite3-dev because we want to use add sqlite support to Rails via gem.

After sqlite is installed, we can add sqlite support to Rails by running the following command.

$ sudo gem install sqlite3 -v '1.3.11'

Install nodejs

Rails do not a built-in web server. It relies on other infrastructure to run. Here, I decide to install nodejs as I am intending to do some other nodejs development later on as well.

$ sudo apt-get install nodejs
$ sudo apt-get install npm

Creating hellorails

After all the setup is done, we can start to create our hellorails application by running the following command:

sudo rails new ./hellorails

Running hellorails

After the application is created, navigate into the directory.
You can run the application by running the following command:

$ rails server

Note: This command will start a web server listening on localhost on port 3000. What this means, is that you can only access the web application on your local machine. To allow other machines to access the web application on port 3000, you need to make the web server listen to the IP address of This can be done by running:

$ rails server -b

An alternative to adding the parameter is edit boot.rb file in the config folder.



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