Linux
Let's Encrypt Kept Failing After a Server Move. The Culprit Was a Second A Record.
Two A records after a migration meant round robin, and Let's Encrypt's multi-perspective validation kept hitting the old server. Diagnosis and fix.
Security
Server security from real incidents: SSH hardening, fail2ban, CrowdSec, firewalls, TLS and mail server pitfalls.
Linux
Mail + Web on One Server: 4 GB or 8 GB of RAM? I Measured It
Real RSS numbers from a panel box with mail and web: ClamAV eats over a gigabyte. Why summing ps lies, how to measure with smem, and when 4 GB is enough.
Docker
My Hosting Panel's Firewall Kept Wiping Docker's iptables Chains
KeyHelp loads its firewall with iptables-restore and flushes Docker's chains. How to spot it, the quick fix, and the options to make it stick.
Linux
Postfix SNI: "map lookup problem" and TLS Alert 80 — the texthash Fix
Per-domain mail hostnames via Postfix SNI: why smtpd hit TLS alert 80 though postmap worked, the ACL fix for Let's Encrypt keys, and test commands.
Linux
Plesk License Expired: What Still Works and How I Got Around It
An expired Plesk license blocks the panel and the plesk CLI, but sites and mail keep running. How I restored a mailbox anyway with mailmng-core.
Linux
My Server Ran Out and My Backups Were Truncated: What I Learned
A Proxmox host went away for good and the offsite backups turned out to be cut off. What I could recover, what was gone, and the checks I run now.
Security
My Blog Went Down Because Plesk Stopped Renewing the Cert — Here's the certbot Escape
A Plesk-managed Let's Encrypt cert expired and took the site down. The fix wasn't renewing it in Plesk — it was moving the domain to standalone certbot. Two gotchas included.
Linux
Tailscale vs WireGuard — Which VPN Should You Actually Run?
Tailscale vs WireGuard compared — Tailscale is built on WireGuard but adds NAT traversal, MagicDNS, ACLs and zero-config mesh. When to pick raw WireGuard instead.
Linux
One Public IP, Many VMs — Port-Splitting a Proxmox Host with nftables
How to route ports 80/443 to one container and 3389/game ports to another VM behind a single public IP on Proxmox — DNAT rules, hairpin, and making it survive a reboot.
Security
CrowdSec — A Modern Take on fail2ban
Set up CrowdSec on Linux as a fail2ban alternative — the agent/bouncer split, parsing logs, the firewall bouncer, community blocklists, and honest trade-offs.
Windows Server
Reset a Windows Password with the Sticky Keys Trick (sethc.exe)
Alternative to the Utilman trick — replace sethc.exe to get SYSTEM-level cmd at the Windows lockscreen. When to use it, how to harden against it.
Linux
Proxmox Backup Server — Why Snapshots Alone Aren't Enough
PBS gives you dedup + incremental + verify on top of Proxmox VE. Install, wire it as storage, first backup + restore, prune policy. The why and the how.