Articles & Guides
Useful resources for web developers and system administrators
Security
What Is a Trojan? How It Works and How to Remove One
What a Trojan is, how it differs from a virus and a worm, the main types, warning signs, and step-by-step removal on Windows 10/11 and Android — plus web shells.
Security
What Is Roskomnadzor (RKN)? Russia's Internet Regulator
What Roskomnadzor (RKN) is, which registries it keeps, how Russian site blocking works and what it means for foreign site owners: data, ads, reachability.
Networking
What Is a Proxy Server? How It Works, Types and Proxy vs VPN
A proxy server relays your requests and shows its own IP to sites. How HTTP, CONNECT and SOCKS5 proxies work, forward vs reverse, common ports and how to detect one.
Security
What Is a Firewall? How It Works and How to Configure One
What a firewall is and how it works: stateless vs stateful vs WAF, Windows Defender Firewall rules, ufw, firewalld and nftables, Docker and cloud traps, port checks.
Networking
What Is DHCP? How It Works, Setup and Fixing DHCP Errors
DHCP explained: how servers lease IP addresses (DORA, ports 67/68, renewal timers), router and Windows setup, and fixes for 'DHCP is not enabled' and 169.254.x.x.
Infrastructure
What Is Apache HTTP Server? How It Works and vs nginx
Apache HTTP Server explained: how it handles requests, MPMs, modules and .htaccess, how it compares to nginx, config paths, key commands and common AH errors.
Networking
What Is 0.0.0.0? Listen Address, Default Route and Hosts File
What 0.0.0.0 means: listen on all interfaces, the 0.0.0.0/0 default route, DHCP and hosts-file blocking. How it differs from 127.0.0.1, with ss and netstat checks.
Tools
Wayback Machine Guide: Find, Save and Remove Archived Pages
How to use the Wayback Machine: open old versions of any site, jump to a date with URL patterns, query the CDX API, save pages and request removal.
Networking
Telnet Port Check: Test Open Ports on Windows, Linux, macOS
How to check a port with telnet: enable the Windows client, use Test-NetConnection or nc, and read refused vs timeout results. Includes a command cheat sheet.
Domains
The .su Domain: Who Owns It, Who Can Register, How to Check
The .su domain was assigned to the USSR in 1990 and outlived it. Who runs the zone today, how it compares with .ru, its reputation risks and how to check a .su name.