Guides tagged “linux”
Step-by-step MdmHost guides about linux, sorted A-Z.
280 guides · page 2 of 14
Change the SSH port safely without locking yourself out
Move SSH to another port in the right order: firewall first, SELinux and Ubuntu socket activation handled, both ports tested, then port 22 closed.
Check disk usage on Linux with df, du and ncdu
Find out how full your Linux VPS disk is with df, see which folders use the space with du, and browse it interactively with ncdu before cleaning up.
Check which Linux distribution and version you're running
Find out exactly which Linux distribution, release and kernel your VPS runs, using /etc/os-release, hostnamectl, lsb_release, uname and the distribution-specific release files.
Check which ports are open and listening on Linux
Use ss and lsof to list every listening port on your VPS, find the process behind each one, tell localhost from public bindings and close what you do not need.
Check your VPS CPU, RAM and disk from the command line
Confirm how many CPU cores, how much memory and how much disk space your Linux VPS has with nproc, lscpu, free, df and lsblk, and check the virtualization type.
chmod: change file permissions in Linux (with examples)
Use chmod to change who can read, write and run files on your Linux server, with numeric and symbolic modes, recursive changes, and a quick way to check the result.
chown: change file owner and group in Linux
Use chown and chgrp to change who owns files on your Linux server, fix web root ownership after an upload, work recursively and understand how symbolic links are handled.
Close unused ports and disable unneeded services on Linux
Fewer running services means fewer things to patch and attack. List what listens on your VPS, disable what you do not use, bind private services to localhost and firewall the rest.
CloudLinux resource limits for resellers: what each limit means and plan maximums
What CPU, PMEM, I/O, IOPS, EP and NPROC mean, which reseller plans include CloudLinux Manager, and the maximum limits per package or account on every plan.
Configure a static IP and add extra IPs on a Linux VPS (Netplan and nmcli)
Set a static IPv4 address, gateway and DNS, and add additional IPs on Ubuntu with Netplan or on AlmaLinux and Rocky with NetworkManager (nmcli).
Configure firewalld on AlmaLinux and Rocky Linux
Learn the firewalld basics on AlmaLinux and Rocky Linux: zones, opening services and ports, permanent versus runtime rules, and IP-restricted access.
Configuring advanced caching layers with Varnish on top of Nginx
Put Varnish in front of Nginx as an HTTP accelerator: install it, write a VCL that caches the right pages, terminate TLS in Nginx and confirm real cache hits.
Connect MySQL Workbench, HeidiSQL or DBeaver to your VPS over SSH
Manage the MySQL or MariaDB database on your VPS from a desktop client through an SSH tunnel, without opening port 3306 to the internet.
Connect to a Linux VPS with PuTTY on Windows
Install PuTTY on Windows, connect to your Linux VPS by IP address and port, accept the host key safely, log in, save the session and adjust the font and colours.
Connect to your Linux VPS with SSH from Windows, Mac or Linux
Find your login details, connect over SSH from Windows, macOS or Linux, confirm the host key, save a shortcut and fix the most common first-login errors.
Convert keys between PuTTY (.ppk) and OpenSSH formats
Use PuTTYgen to convert a PuTTY.ppk private key to OpenSSH format and back, understand PPK version 2 and 3, generate a new Ed25519 key and load it in PuTTY.
Copy, move and rename files in Linux (cp and mv)
Use cp and mv to copy, move and rename files and folders on a Linux server, keep permissions intact with cp -a, avoid accidental overwrites and rename many files at once.
cPanel cron jobs: create and manage scheduled tasks
Use cPanel's Cron Jobs tool to run scripts and backups on a schedule, route the job's output to an email address, and edit or remove entries later.
Create a shared folder several users can edit
Set up a folder on your Linux VPS that a team can all read and edit, using a shared group, the setgid bit, a 002 umask or default ACLs, and test it with two users.
Create a sudo user on Ubuntu, Debian, AlmaLinux and Rocky Linux
Add a personal admin account with sudo rights, give it your SSH key, and test it properly before you stop logging in as root.
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