Recently, I upgraded the FreeIPA server for my network to the latest version (4.8.10). Some strange things related to authentication started to happen with some services on my network.

For our Web site, netlify gotrue is used to enable users to login using SAML Single Sign-On. This started …

One of the latest fashions in the Java world is GraalVM. For someone who has been around, I still remember the "Write once, run anywhere" slogan of Java virtual machine. Apparently, the wheel has spun back, now people want to write native code in Java, which has to be compiled …

For a public facing Web interface of FreeIPA server, it is desirable to use a 3rd party SSL certificate issued by a commonly accepted certificate authority, rather than using the server's own. Let's Encrypt provides free SSL certificate for this purpose.

To use Letsencrypt certificate with FreeIPA, this script does …

The main product of my startup is written in Clojure, a language that puts enormous pressure on the memory garbage collector due to the pervasive use of immutable data structures. The new Z garbage collector on JVM has been a blessing for us, as it has largely solved our memory …

With newer versions of on-premise Sentry (I am using Sentry 20.10.1), the LDAP authentication does not seem to work any more. The code still compiles but the LDAP login UI does not show up. Fortunately, newer versions of Sentry provide built-in support for SAML2 authentication, so we can …

To control access to various internal Web sites of a company, a simple method is to enable LDAP authentication on the Web server, so that the company directory can be brought to bear and there is no need to create individual accounts for employees on different systems.

Nginx is one …

If you are using a self-hosted Netlify CMS as the online editor for your SSG powered Website and you are using the editorial workflow (you have publish_mode: editorial_workflow in your config.yml), a pain point is that you do not see a preview of the live page when the page …

Static Site Generator (SSG) is in vogue for building Web sites. Compared with traditional content management system (CMS), SSG is more performant, flexible and easier to maintain for people comfortable with coding . However, for the non-technical crowd, a WYSIWYG online editor is still the way to go. Netlify CMS fills …

This blog has undergone a few migrations over its 15 years life span.

It started out as a Blogger account in 2005. The purpose was to record some system administration details when I was an assistant professor at university, setting up my laboratry for students.

Then Yunyao joined in after …

DokuWiki is one of the most easy-to-use open source Wiki software. It is a very good internal documentation tool for small or medium sized organizations.

Comparing with using Google Docs for the same purpose, one advantage of using a Wiki is that it is more searchable and navigable. In addition …

Discourse is a modern forum software that is quite popular in the technology circle. One can install a Discourse server easily with the recommended method of using docker. All the services needed by the Discourse server, e.g. Postgresql and Redis, will be running inside a docker container, which is …

Sentry is a fairly popular service for tracking exceptions and errors in production softwares. They also provides a docker recipe for people who want to self host their own sentry server. This post shows how to enable LDAP authentication for such a self hosted sentry server, using freeIPA as the …

The point of setting up freeIPA for an intranet is to enable single-sign-on (SSO) for all the internal services that requires authentication and authorization. LDAP, originated from my alma mater University of Michigan, is one of the most widely accepted solutions to the problem. freeIPA can serve as a LDAP …

FreeIPA is the open source version of RedHat's identity management solution, which nicely integrates several open sources services that are important for managing an intranet: 389 LDAP Directory Server, MIT Kerboros, NTP, DNS, SSSD and others. 

Most of my servers are virtual machines in AWS EC2. To manage such a …

Since Drupal 6 is no longer supported, I upgraded this site to the lasted version of Drupal 8.4.2 by following the guide. As you can see, the upgrade mostly worked. However, there are a few points of caution as well as some unresolved problems.

As before, I setup …

The IT department of my company has been urging us Mac users to upgrade OSX to Lion a long time ago. After getting a few papers submitted last week, I finally got around to upgrade the Snow Leopard for my Macbook Pro work machine. Since I couldn't find Lion on …

If you have one or more long hair cats at home, like our Mayori and Tom, you probably share the same dream as us --- a house without cat hair, at least a house without having cat hair everywhere.

Towards this dream, we have tried out various products. Here is a …

While preparing the camera-ready version for our CIKM demo, my colleagues and I found that the screenshot included in our paper appeared to be fairly blurry in the pdf version, even though the original .jpg file looks fine.

I searched online to try to find the solutions. After a few …

For unknown reason, my machines would suddenly disable their screen saver options (e.g. with the "on resume, display log on screen" check box grayed out). Whenever this happens, it would trigger the security alert and I will get a warning from the IT department to fix the issue.

I …

As previously mentioned, I am learning category theory, beginning with Lawvere's Conceptual Mathematics book. This is a very elementry book that assumes almost nothing as a background. However, it is still a math book, which requires doing some exercises. Since the book provides no answer to exercises, I decide …