Netplan: Configure a Static IP Address on Ubuntu
Set a static IP on Ubuntu with Netplan: YAML structure, addresses, routes, DNS, multiple IPs, netplan try for safe changes, and fixing common errors.
Blog
Networking
DNS, reverse proxies, bandwidth, routing and network performance.
DNS Propagation Explained: Why DNS Changes Take Time
Why DNS changes aren't instant: TTLs, resolver caching, record vs nameserver changes, checking propagation with dig, and zero-downtime server migrations.
HTTP/1.1 vs HTTP/2 vs HTTP/3: Differences and Why They Matter
HTTP/1.1 vs HTTP/2 vs HTTP/3: multiplexing, header compression, head-of-line blocking, QUIC over UDP, performance impact, and enabling each on your server.
MX Records Explained: Set Up Email Routing for Your Domain
How MX records route email: priorities, Google Workspace, Microsoft 365 or your own mail server, rules (no CNAME, no IP), testing and troubleshooting.
nslookup Command: DNS Lookups on Windows, macOS and Linux
Use nslookup to check A, MX, TXT and NS records, query a specific DNS server, do reverse lookups and use interactive mode, on Windows and Linux alike.
Subnetting and CIDR Notation Explained (with Cheat Sheet)
CIDR notation explained: /24 and /32, subnet masks, network and broadcast addresses, host counts, splitting networks, IPv6 prefixes, and firewall use.
ping, traceroute and mtr: Diagnose Network Latency and Loss
Measure latency and packet loss with ping, map the path with traceroute, combine both with mtr, and learn what really indicates a network problem.
Email Deliverability for Self-Hosted Mail: Get Out of Spam
Get mail from your VPS into the inbox: PTR and HELO, SPF, DKIM and DMARC alignment, IP and domain reputation, Gmail and Outlook sender rules, and testing.
Squid Proxy Server on Ubuntu: Install, Authenticate and Secure
Set up a Squid HTTP/HTTPS forward proxy on a VPS: install, allow only your IPs or password users, HTTPS via CONNECT, caching, logging, no open proxy.
BGP Basics: How the Internet Routes Traffic Between Networks
BGP made approachable: autonomous systems and ASNs, prefixes and announcements, peering vs transit, why routes affect latency, BGP hijacks and RPKI.
Headscale: Self-Host the Tailscale Control Server on a VPS
Run Headscale, the open-source Tailscale control server, on a VPS: install, TLS, users, registering devices, ACL policies, MagicDNS and exit nodes.
How to Open a Port on Linux (UFW, firewalld, iptables)
Open a TCP or UDP port on Ubuntu, Debian, AlmaLinux and Rocky with UFW, firewalld, iptables or nftables — and make sure a service is actually listening on it.
Load Balancer Types Explained: L4 vs L7, DNS, Hardware and Cloud
Load balancing compared: layer 4 vs layer 7, DNS round robin and GeoDNS, Nginx, HAProxy and Envoy, algorithms, health checks, sticky sessions, HA.
HAProxy TCP Mode: Load Balance Databases, Redis and TCP Services
Use HAProxy in TCP mode: proxy and balance MySQL, PostgreSQL and Redis, health checks, SNI routing for TLS passthrough, the PROXY protocol, timeouts.
PowerDNS Authoritative Server: Host Your Own DNS Zones
Host your own DNS zones with PowerDNS: SQLite or MySQL backend, zones and records with pdnsutil, primary and secondary servers, DNSSEC, API and web UI.
Configure IPv6 on a Linux Server (Netplan, ifupdown, nmcli)
Add a static IPv6 address and gateway on Ubuntu, Debian or RHEL, test connectivity, make Nginx and the firewall IPv6-ready, and fix common IPv6 problems.
NAT Explained: How Network Address Translation Works
How NAT works: private networks sharing public IPs, SNAT vs DNAT, connection tracking, CGNAT and its hosting problems, NAT on Linux servers, IPv6.
CN2 GIA Explained: China Telecom Premium Routes for Servers
What CN2 and CN2 GIA are, how they differ from China Telecom’s 163 backbone and CN2 GT, why they matter for users in China, and checking routes with mtr.
How to Check Open Ports on Linux (ss, netstat, lsof, nmap)
List listening ports and the processes behind them with ss, netstat and lsof, find what uses a port, and scan your server from outside with nmap.
DNSSEC Explained: Signed DNS, DS Records and How to Enable It
How DNSSEC protects DNS answers from forgery: signatures, DNSKEY and DS records, the chain of trust, enabling it at your DNS host, and avoiding outages.
DNS TXT Records: Verification, SPF, DKIM and More Explained
What DNS TXT records do: domain verification, SPF, DKIM and DMARC, ACME challenges, formatting long values, multiple TXT records, and checking them.
CAA Records: Control Which CAs Can Issue Your SSL Certificates
Use CAA records to allow only Let’s Encrypt or your chosen CA, restrict wildcards with issuewild, add iodef reports, and avoid breaking renewals.
vnStat: Monitor Bandwidth and Monthly Traffic on a Linux Server
Track traffic per hour, day and month with vnStat: install, pick the interface, live rates, monthly totals against your plan, alerts, and JSON output.
Set Up a WireGuard VPN Server on Ubuntu or Debian
Build your own WireGuard VPN on a VPS: install, generate keys, configure wg0, enable IP forwarding and NAT, add clients with QR codes and troubleshoot.