VPS & Linux glossary

Every term you’ll meet while running a Linux VPS — SSH, services, mail, security, databases — explained in plain language. Click a term for the full page.

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

A

  • Apache (httpd) The most widely used web server on hosting panels — the service that actually answers HTTP requests for your …

B

  • Brute-force attack Automated guessing of passwords — against SSH, mail or admin panels — at thousands of attempts per hour.

C

  • cPanel The most widespread commercial hosting control panel — the de-facto standard layout for shared and reseller s…
  • Cron Linux’s scheduler — runs commands at set times. Backups, certificate renewals and maintenance all live here.
  • Crontab The per-user file listing that user’s scheduled cron jobs — edited safely only through the crontab command.
  • CSF (ConfigServer Security & Firewall) The firewall manager standard on SPanel/cPanel servers — the practical way IPs get blocked and unblocked.

D

  • Disk quota A per-account limit on disk usage (and often inodes) that stops one hosting account from filling the whole se…
  • DKIM (DomainKeys Identified Mail) A cryptographic signature your mail server adds to outgoing email, proving it really came from your domain un…
  • DMARC A DNS policy telling receivers what to do with mail that fails SPF/DKIM — and the alignment glue that makes b…
  • DNS (Domain Name System) The internet’s phone book — translates domain names into IP addresses. Most “site is down” mysteries are DNS.

E

  • Exim The mail transfer agent (MTA) used by SPanel/cPanel servers — the service that actually sends and receives em…

I

  • Inode The filesystem record describing one file. Disks can run out of inodes — “no space left” while gigabytes are …
  • IO-wait The share of time the CPU sits idle only because processes are waiting for the disk — the classic hidden bott…

L

  • Let's Encrypt The free, automated certificate authority behind most of the web’s HTTPS — 90-day certificates renewed by sof…
  • Linux The open-source operating system that runs the overwhelming majority of web servers, including virtually ever…
  • Load average Linux’s headline “how busy am I” number: the average count of processes running or waiting, over 1, 5 and 15 …

M

  • MariaDB A community fork of MySQL, fully compatible and the default database on many hosting servers.
  • ModSecurity A web application firewall (WAF) inside Apache that inspects every request and blocks common attack patterns.
  • MySQL The world’s most common open-source database server — where almost every CMS keeps its content, users and ord…

P

  • PHP-FPM The process manager that runs PHP for your websites — each site or account typically gets its own pool of PHP…
  • PTR record (reverse DNS) The DNS record mapping an IP address back to a hostname — mail servers check it before trusting your email.

R

  • RBL / DNSBL (blacklist) Real-time blacklists of IPs known to send spam. Landing on one means widespread mail rejection until delisted.
  • root (superuser) The all-powerful administrator account on a Linux system — it can read, change or delete anything.

S

  • SPanel ScalaHosting’s all-in-one hosting control panel — a cPanel alternative managing accounts, domains, mail and d…
  • SPF (Sender Policy Framework) A DNS record listing which servers may send email for your domain — the first pillar of mail authentication.
  • SSH (Secure Shell) The encrypted protocol used to log in to and run commands on a Linux server remotely — the standard way to ad…
  • SSH key A cryptographic key pair used instead of a password for SSH logins — far more resistant to brute-force attack…
  • SSL/TLS certificate The cryptographic credential behind HTTPS — proves your site’s identity and encrypts traffic. Expired = scary…
  • Swap Disk space used as overflow when RAM runs out. A little swap is normal; heavy swapping makes everything crawl.
  • systemd / systemctl The Linux service manager — systemctl starts, stops, restarts and reports the status of services like Apache …

U

  • Uptime How long the server has run since its last boot — and, loosely, the share of time your services are actually …

V

  • VPS (Virtual Private Server) A virtual machine rented from a hosting provider that behaves like your own dedicated Linux server, with root…

W

  • Web shell A small malicious script (usually PHP) planted on a hacked site, giving the attacker remote control through t…