Server Management

A SHA-256 digest can help detect whether a downloaded file differs from a reference value. It does not, by itself, prove who created the file. The ref...

Performance tuning is most useful after you identify a measurable bottleneck. A high CPU percentage, low free-memory number or large disk queue is a c...

Nginx and Apache can serve web content directly or participate in a reverse-proxy chain. Security depends on the full path from the client through pro...

Keeping a Linux server patched is a recurring operational task. A safe process identifies the release and repositories, reviews the proposed changes, ...

SMTP status 421 usually indicates that a service is temporarily unavailable or closing the connection. The text following the code and the server that...

A firewall rule should reflect a service that is meant to be reachable. Before enabling UFW, inventory listening sockets and map each one to its owner...

Fail2Ban watches configured logs and applies temporary blocks when activity matches a filter and jail policy. It can reduce repeated login attempts re...

If a website opens on a phone but not on one computer, the server may still be healthy. Compare the failing computer with a working device to isolate ...

A query that appears stuck may be waiting for a lock held by another transaction. Finding the blocker is safer than cancelling sessions at random, bec...

When CPU load climbs, a disk fills up or an RDP connection drops, the first step is to gather the right evidence. My Linux and Windows GitHub reposito...