#security

Network security, application security, CTFs, and hardening.

2026-07-01 Building a passive Ethernet tap #hardware #networking #security Ata Kuyumcu
Cloning the Throwing Star LAN tap on mini breadboards for €10 to see how chatty my smart TV is. No power, no software, physically receive-only.
2026-06-26 Revisiting server hardening #devops #security Ata Kuyumcu
Six things my Linux hardening baseline missed, found on a fresh Debian 13 VPS, plus post-quantum SSH key exchange in one config line.
2026-04-23 Hardening a fresh Linux install #devops #security Ata Kuyumcu
The baseline I apply to every fresh VPS: non-root user, SSH lockdown, UFW, fail2ban, unattended upgrades, and the Docker firewall hole.
2018-10-01 I did a few things at STM CTF 2018 Prelims #security #python Ata Kuyumcu
Writeups for three challenges from the STM CTF 2018 prelims: DiEfAyAr, Rengarenk String, and Matruşka.
2018-03-01 I did a thing at Harekaze CTF 2018 #security #cryptography #python Ata Kuyumcu
One crypto challenge from Harekaze CTF 2018: gacha, an RSA service solved while waiting for another CTF to start.
2017-12-04 I did a thing at TU CTF 2017 #security #cryptography #python Ata Kuyumcu
The Neverending Crypto at TU CTF 2017: scripting a Caesar cipher breaker in Python fast enough to keep up with the rounds.