Featured~7min read
DNS From First Principles
A grounded walkthrough of how DNS actually resolves, the records that matter, and the security boundaries every defender should understand.
#networking#dns#cybersecurity
$ 0xrcos
Cybersecurity & technology notes — learning in public
~/notes — zsh
0xrcos:~$ whoami cybersecurity learner 0xrcos:~$ cat focus.txt - networking fundamentals - linux & hardening - web app security - python tooling 0xrcos:~$ ls posts/ | wc -l 5 0xrcos:~$
Recent writing
View all posts →~8min readprogramming
Python for Security Tooling: A Port Scanner and a Hash Cracker Sketch
A practical, beginner-friendly intro to writing small security tools in Python — a concurrent port scanner and a dictionary hash cracker, with ethics baked in.
~7min readnetworking
TCP/IP Notes: The Four Layers, the Handshake, and Reading a Packet
Study notes on the TCP/IP model — the four layers, the three-way handshake, TCP states, and a practical look at reading a packet capture with tcpdump and tshark.
~7min readlabs
My First TryHackMe Room: A Beginner Walkthrough (Methodology, Not Spoilers)
A learning-in-public write-up of the methodology I used on my first TryHackMe beginner Linux room — recon, enumeration, and the mindset that finally clicked.
~6min readlinux
Linux File Permissions, Without the Magic
A grounded tour of rwx, octal notation, chmod, chown, umask, and the special bits — explained the way I wish someone had explained them to me.