ITSO (formerly ITSC)*, shorted by Information Technology Services Office, is the IT department of our HKUST university.

Official Website: itso.hkust.edu.hk

• Reloaded toners🖋️ and papers📄 at campus-wide printers🖨️.
• Reported the "Lazy Problem"😴 of many other student helpers with a Sense of Responsibility.
  "If the printers are out of paper❌, how can students print notes, study and do revision?"
• Checked and maintained classroom A/V equipment📹🎤 in 2025 Winter, upgrading computer operating systems.
• Reported faulty🚧 equipment and stopped offences⚠️ (e.g., leaving items🎒📚💻 unattended) in Computer Barns.
• Patiently answered IT-related questions and resolved issues from students🙋‍♂️ in both Computer Barns and ITSO Office (Service Desk).

* Our university ITSC department renamed to ITSO in January 2025.

USThing is a student group with an all-in-one student-developed HKUST university app.

Official Website: usthing.xyz

• Maintained app developer documentation📄 (e.g., Developer Tool🛠️ Installation Guide for New Members).
• Responded to user feedback💬 and enquiries.
• Selected☑️ and interviewed💬 new applicants.
• Guided members to work on new features🌟 and fix bugs🐞.
• Reviewed codes (GitHub Pull Requests) by members.

COURSEMO is an educational institution for international courses, exams and even competitions (e.g., IB, IGCSE, A Level, AP).

Official Website: coursemo.com

• Developed a Student Management📋 & Attendance☑️ System.
• This system was also adopted✅ and used by our high school🏫 (GCGS).

This research was followed by an incident on Ken's Study Planner in April 2024 - Degraded Performance.

After a careful investigation, it was caused by the excessive data records in one specific database table and hence server overload (nearly 100% CPU and memory usage).

I then solved this issue with Hash Algorithm and Data Buckets (i.e., separate tables).

Each table is split into 10 to 1,000 buckets depending on the data size estimated.

When I share a link on social media, what crawled my website came from a different IP address than the social media website.

When I do DNS Lookup (nslookup) of the same website in different cities, I get different IP addresses.

So, why is this? Is it using a CDN?

Yes, but it's partially true.

Simply speaking, the Web Server and Spider Server (Crawler) have different IP addresses.

To learn more, I researched about it and applied the same concept on my projects.

Apart from the server structure, I also implemented some Web Security mechanisms, including:

• SQL Injection Attack Prevention
• XSS (Cross-Site Scripting) Attack Prevention
• User Access Control
• Email Address Encryption with JavaScript (Spambot & Crawler Prevention)

When I access certain websites, I may get:

• (Domain Name) takes too long to respond.
• The connection was reset.
• "Access Denied/Blocked" Page
• (etc.)

I know it's a firewall. But how does it actually work and where are they located?

In this research, I made use of Net Tools and commands, including:

• ping: Check the Internet latency to another computer/server.
• tracert, traceroute & mtr: Display the IP addresses of routers to a computer/server.
• nslookup: Display the IP address of website domain names.
• nc (netcat): Check the accessibility of a port. (e.g., nc -z -v ken.kenstudyjourney.cn 443)
• Wireshark: Capture and analyse TCP/IP packets.

Based on the results (simplified):

• The routing (tracert/traceroute) depends on the direct connections between 2 ISPs (peers).
• The firewall may Drop Packets, do DNS Poisoning, Change HTTP Webpage Content and TCP Connection Reset (RST bit = 1, according to Wireshark) based on IP and domain name blacklists.
• When a packet is dropped, tracert/traceroute command can be used to locate where the firewall is.

For example, the Game Firewall in high school and Phishing Firewall at university have the exactly same working principle:

• HTTP: Website Content Hijacking
• HTTPS: SNI Filtering (TCP Connection Reset; RST bit = 1)

As part of my high school EPQ Project, I explored and applied some new technologies behind my website, including:

• IPv6
• HTTP/2
• HSTS (HTTP Strict Transport Security)
• DNS CAA (Certificate Authority Authentication)