ssl

Notes about setting up HTTPS on websites using LetEncrypt and certbot

By Alvin Alexander. Last updated: March 25 2019

As a note to self, I added SSL/TLS certificates to a couple of websites using LetEncrypt. Here are a couple of notes about the process:

Read the LetEncrypt docs
They suggest using certbot
Read those docs, and follow their instructions for installing the packages you’ll need
Make sure your server firewall rules allow port 443 (You may get an “Unable to connect to the server” error message if you forget this part, as I did)
After making some backups, run this command as root:

How to update the Java keystore with a website certificate (Let’s Encrypt)

By Alvin Alexander. Last updated: June 17 2018

As a brief note to self, I use these Java keytool commands to add/update the SSL certificate for accessing a website named alphavantage.co:

The keytool password for the Java security cacerts file is ...

By Alvin Alexander. Last updated: June 17 2018

In case you ever need to manually a certificate to your ${JAVA_HOME}/jre/lib/security/cacerts file, it turns out the password for that file when using the Java keytool command is changeit.

To add a certificate to that file, you’ll want to use a command like this:

keytool \
    -import \
    -alias "foobar.com" \
    -keystore ${JAVA_HOME}/jre/lib/security/cacerts \
    -file foobar.com.crt

I had to do this today for a Java/Scala script that accesses an HTTPS URL, and the site I’m accessing uses a “Let’s Encrypt” certificate.

Notes on how to configure HTTPS/SSL with Nginx (on a Linode Ubuntu server)

By Alvin Alexander. Last updated: April 4 2018

Summary
New Linode Server
Update Everything
Ubuntu Firewall
Add a New User
Disabling Root Login (sshd_config)
Limit Login Attempts (sshd_config)
Install Nginx and MySQL
Adjust Firewall
Nginx Configuration
Installing Java on Ubuntu
NOT what I used: Let’s Encrypt on Ubuntu 16.04
(1) Create a cert (openssl)
(2) Create a strong Diffie-Hellman group
(3) Configure Nginx to Use SSL
Adjust the Nginx Configuration to Use SSL
(Alternative Configuration) Allow Both HTTP and HTTPS Traffic
Adjust the Firewall
Enable the Changes in Nginx
Test in Browser
Nginx "default_server"
Can change to a permanent redirect (301)
More Security: Preventing Information Disclosure
More Security: Fail2Ban
Restricting Access by IP Address
See also

Table of Contents1 - Summary2 - New Linode Server3 - Update Everything4 - Ubuntu Firewall5 - Add a New User6 - Disabling Root Login (sshd_config)7 - Limit Login Attempts (sshd_config)8 - Install Nginx and MySQL9 - Adjust Firewall10 - Nginx Configuration11 - Installing Java on Ubuntu12 - NOT what I used: Let’s Encrypt on Ubuntu 16.0413 - (1) Create a cert (openssl)14 - (2) Create a strong Diffie-Hellman group15 - (3) Configure Nginx to Use SSL16 - Adjust the Nginx Configuration to Use SSL17 - (Alternative Configuration) Allow Both HTTP and HTTPS Traffic18 - Adjust the Firewall19 - Enable the Changes in Nginx20 - Test in Browser21 - Nginx "default_server"22 - Can change to a permanent redirect (301)23 - More Security: Preventing Information Disclosure24 - More Security: Fail2Ban25 - Restricting Access by IP Address26 - See also

Without any introduction or discussion, here are the notes I made while learning how to get HTTPS working with Nginx. These are just for me, but if something helps you, cool.

A Scala IMAP email client (using SSL, IMAPS, JavaMail)

By Alvin Alexander. Last updated: June 18 2017

If you ever need to write an IMAP client in Scala, I hope the following example can be helpful. For my project named SARAH (a Mac OS X Siri-like project), I wanted an IMAP client to periodically check my mail and then say something a little better than, "You've got mail", and the first part of that was getting a Scala IMAP client going.

Private Git repository hosting services

By Alvin Alexander. Last updated: August 11 2018

Private Git hosting services FAQ: What companies offer Git hosting, in particular private Git hosting services?

I recently started looking for a private Git hosting service, and the obvious first place to look is GitHub. They provide free Git hosting for open source projects, and their service has been excellent. But when I looked at their private Git hosting service, I was really surprised by the cost of their plans. Their lowest price private Git hosting plan is $7/month, and that allows only five Git projects, and relatively little disk space. Since I want a private Git hosting service to store all my projects, I'd immediately need to go to one of their paid Git hosting plans, and their Git hosting prices go up quickly from there.

Update: Github has changed their policies significantly since I first wrote this article.

Test your Putty SSH tunnel and Firefox SOCKS proxy

By Alvin Alexander. Last updated: June 3 2016

(This is the final part of a four-part tutorial. Here's a link to the introduction.)

Step 5: Test your Putty SSH tunnel and Firefox SOCKS proxy

As an initial test of the tunnel just try to go to a website like google.com in Firefox. If everything has been configured right, and your Putty tunnel is up and running, you should connect just fine.

Configure Firefox to use the Putty SSH tunnel as a SOCKS proxy

By Alvin Alexander. Last updated: June 3 2016

(This is Part 3 of a four-part tutorial. Here's a link to the introduction.)

Step 4: Configure Firefox to use the Putty SSH tunnel as a SOCKS proxy

Configuring Firefox to use this new SSH tunnel is simple. Start Firefox, then select the Tools menu, and then select the Options... menu item. Now click the Advanced icon (on the upper-right of the dialog), and then select the Network tab. This is shown in the next figure:

Configuring a tunnel to your SSH server

By Alvin Alexander. Last updated: June 3 2016

(This is Part 2 of a four-part tutorial. Here's a link to the introduction.)

Step 3: Configuring a tunnel to your SSH server

Next, we'll use Putty to create an SSH tunnel and connect to your remote server. For the purposes of this example let's assume we are connecting to a site named "myremotesshserver.com".

When you start Putty you should see a window that looks like the next figure:

A PayPal PHP IPN example

By Alvin Alexander. Last updated: June 3 2016

If you're looking for a PayPal IPN example written in PHP, I believe the following code works okay. It's based on the PayPal PHP IPN example (from the PayPal developer site), but I fixed some bugs from their example, added an alternate PHP socket example so you don't have to use SSL to connect to PayPal, and added more variables to the script.

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