Knowledge Base

Guides, tutorials, and answers to help you get the most out of Xitoring.

95 articles found

How to add a user to sudoers in AlmaLinux or Rocky Linux

Granting sudo on AlmaLinux or Rocky Linux is a one-liner — but the right shape of that grant (wheel group vs `/etc/sudoers.d/`, password vs NOPASSWD, all commands vs a narrow list) decides whether the next admin inherits a clean setup or a footgun. This guide walks through every common way to add a user to sudoers on RHEL-derived distros, how to verify the grant works, and how to avoid the classic mistakes that lock you out of the box.

linuxalmalinuxrocky-linuxrhelsudosudoerssecuritysysadmin

Server Monitoring

How to fix the 403 Forbidden error in Nginx

A 403 Forbidden Nginx response means the server understood the request and refused to serve it — but Nginx rarely tells the client why. The cause is almost always one of five things: file permissions, a missing index file, SELinux, an explicit deny rule, or a misbehaving upstream. This guide walks through them in the order to rule them out, with the exact commands and the log lines that tell you which is which.

nginxhttp403forbiddentroubleshootingpermissionsweb server

Server Monitoring

How to fix the 500 Internal Server Error in Nginx

A 500 Internal Server Error from Nginx almost never originates in Nginx itself — the response is what reaches the client when the application upstream (PHP-FPM, Node, Python, Go) crashed, returned malformed output, or never responded at all. This guide walks through how to tell a real Nginx 500 apart from an upstream 500, how to find the root cause in the error log, and how to fix the most common culprits without guessing.

nginxhttp500internal-server-errortroubleshootingphp-fpmweb server

Server Monitoring

How to monitor CPU temperature on Windows/Linux?

CPU temperature is one of the first vitals to check when a server slows down, a workstation throttles, or a fan suddenly screams. This guide walks through the built-in and free tools to read CPU temperature on Windows and Linux, what the readings actually mean, safe operating ranges, and how to wire temperature into continuous monitoring so you find out before users do.

cputemperaturethermallinuxwindowsmonitoringtroubleshooting

Server Monitoring

How to set up and configure an NTP server on CentOS 7

Accurate, consistent time is a hard requirement for log correlation, TLS, Kerberos, database replication, and almost every distributed system you operate. This guide walks through installing, configuring, and hardening an NTP server on CentOS 7 — including chronyd vs ntpd, peers and stratum, firewall rules, verification, and how to monitor drift before it bites.

ntpchronycentoslinuxtimemonitoring

Networking & Diagnostics

Using the Windows ipconfig command

ipconfig is the built-in Windows tool for inspecting IP configuration, releasing and renewing DHCP leases, and clearing the DNS cache. This guide covers the flags you will actually use, how to read the output, and the recipes that solve the most common networking problems on Windows.

windowsnetworkingipconfigdnstroubleshooting

Networking & Diagnostics

What is a 504 Gateway Timeout — meaning, causes, and how to debug it

The 504 Gateway Timeout meaning is precise: a server acting as a gateway reached the upstream it was supposed to talk to, but the upstream did not finish responding in time. It almost never means "the internet is broken" — it means something further down the chain is slow. This guide explains what 504 actually means, who returns it, and how to find the real root cause instead of just raising timeouts.

http504gateway-timeouttroubleshootingnginxcdnperformance

Networking & Diagnostics

How to install and use tcpdump?

tcpdump is the de-facto command-line packet analyzer for system administrators. This guide covers installation on Linux, macOS, and Windows, the most useful flags, BPF filter syntax, and practical recipes for diagnosing real network problems on a server.

tcpdumpnetworkinglinuxtroubleshootingpcap

DevOps & Workflow

How to remove a file from git history

Committed a secret, a multi-gigabyte binary, or a file that should never have been tracked? Removing it from the working tree is not enough — git remembers everything. This guide covers how to scrub a file from your entire history with git filter-repo or BFG, and what to do afterwards.

githistory-rewritesecretsfilter-repobfg

DevOps & Workflow

How to rename a git branch

Renaming a git branch is straightforward locally but takes an extra step on the remote and on every other clone. This guide covers renaming the current branch, another branch, the default branch (master to main), and updating tracking after the rename.

gitbranchrenameworkflow