LiteSpeed Web Server Users' Manual - Introduction
Description: LiteSpeed Web Server Users' Manual - Introduction.

## LiteSpeed Web Server
Users' Manual

### Version 6.3 — Rev. 4

- License Enterprise
- Introduction
- Installation
- Administration
- Security
- Configuration
  - Server General
  - Server Log
  - Server Tuning
  - Server Security
  - Page Cache
  - PageSpeed Config
  - External Apps
  - Fast CGI App
  - Fast CGI Authorizer
  - LSAPI App
  - Servlet Engine
  - Web Server
  - Piped logger
  - Load Balancer
  - Script Handler
  - PHP
  - App Server Settings
  - Listener General
  - Listener SSL
  - Virtual Host Templates
  - Virtual Host Basic
  - Virtual Host General
  - Virtual Host Security
  - Virtual Host SSL
  - Virtual Host PageSpeed Config
  - Rewrite
  - Context
  - Static Context
  - Java Web App Context
  - Servlet Context
  - Fast CGI Context
  - LSAPI Context
  - Proxy Context
  - CGI Context
  - Load Balancer Context
  - Redirect Context
  - App Server Context
  - Rack/Rails Context
  - Add-ons
- Web Console
  - Admin Console General
  - Admin Console Security
  - Admin Listener General
  - Admin Listener SSL

# Introduction

### Overview

LiteSpeed Web Server is an Apache-interchangeable, high performance, secure, easy-to-use web server. It can handle thousands of concurrent connections with a small memory footprint. Its security features also make it much less vulnerable to various attacks.

### LiteSpeed Exclusive Features

- Apache Drop-In Replacement
- HTTP/2 Support
- QUIC Support
- Zero Downtime
- Anti-DDoS Advances
- Event-Driven Architecture

### Features

- HTTP/1.1

  - HTTP/2
  - HTTP 1.0/1.1 compliant
  - Scripting Languages: PHP, Perl, Ruby, Python, Java, etc...
  - Server APIs: LiteSpeed SAPI (LSAPI), CGI, FCGI, AJPv13, Proxy
  - HTTPS
  - IPv4 and IPv6
  - Unlimited IP and name-based virtual hosting
  - Unlimited concurrent connections
  - GZIP compression
  - Support for SPDY/2, 3, and 3.1
  - WebSocket proxying
  - Runs on Linux, FreeBSD, MacOSX, Solaris

- Performance & Scalability

  - Event-driven architecture
  - Hundreds of thousands of concurrent connections
  - Tiny memory footprint
  - Sendfile()
  - Asynchronous I/O support
  - LiteSpeed's exclusive server API (LSAPI) delivers the best dynamic content performance
  - Unrivaled PHP suEXEC performance for shared hosting
  - Three different PHP process modes for different needs and abilities
  - Static content up to 5x faster than Apache
  - Dynamic content up to 40x faster than Apache
  - HTTPS 3x faster than Apache
  - OCSP stapling
  - Built-in page caching
  - Turbocharge Magento and other web applications with ESI support
  - Advanced .htaccess caching removes performance bottlenecks associated with .htaccess use in Apache
  - CloudLinux LVE compatibility
  - Increases scalability of web applications
  - Separation of server and web applications allows for buffering of requests and responses, leading to better handling of multiple connections
  - Just in time configuration cuts restart time
  - CPU affinity allows for greater use of CPU cache

- Apache Compatibility

  - Reads Apache's configuration files directly
  - Drop-in Apache replacement for cPanel, Plesk, DirectAdmin, Interworx, etc.
  - Full .htaccess support
  - Compatible with Apache core modules

- Security

  - Built-in anti-DDoS connection and bandwidth throttling
  - mod_security compatibility
  - Compatibility with Atomic Secured Linux and Atomicorp Realtime ModSecurity Rules
  - Anti SSL BEAST and renegotiation attack capabilities
  - Strict HTTP request validation
  - Denies buffer-overrun attempts
  - PHP/Ruby/CGI/FCGI/LSAPI suEXEC
  - CloudLinux CageFS compatibility
  - External application and full server chroot ability

- High Availability

  - Apply changes with zero downtime
  - Zero downtime server software upgrade
  - Recovers from service failure instantly

- Ease of Use

  - Control panel plugins (cPanel, DirectAdmin, and Plesk)
  - Officially supported by cPanel
  - Intuitive WebAdmin console GUI
  - Virtual host templates for easy configuration
  - Real-time service monitoring

- Advanced Features

  - Easily run multiple versions of PHP on one server
  - MS FrontPage Server Extensions
  - Geo-IP lookup
  - Stream logs to external logger
  - Custom log formatting
  - Backend load balancing
  - mp4/flv streaming