Squid: The Definitive Guide: The Definitive Guide

by Duane Wessels

Overview

Squid is the most popular Web caching software in use today, and it works on a variety of platforms including Linux, FreeBSD, and Windows. Squid improves network performance by reducing the amount of bandwidth used when surfing the Web. It makes web pages load faster and can even reduce the load on your web server. By caching and reusing popular web content, Squid allows you to get by with smaller network connections. It also protects the host on your internal network by acting as a firewall and proxying your internal web traffic. You can use Squid to collect statistics about the traffic on your network, prevent users from visiting inappropriate web sites at work or school, ensure that only authorized users can surf the Internet, and enhance your privacy by filtering sensitive information from web requests. Companies, schools, libraries, and organizations that use web-caching proxies can look forward to a multitude of benefits.Written by Duane Wessels, the creator of Squid, Squid: The Definitive Guide will help you configure and tune Squid for your particular situation. Newcomers to Squid will learn how to download, compile, and install code. Seasoned users of Squid will be interested in the later chapters, which tackle advanced topics such as high-performance storage options, rewriting requests, HTTP server acceleration, monitoring, debugging, and troubleshooting Squid.Topics covered include:

• Compiling and installing Squid
• Running Squid
• Using Squid's sophisticated access controls
• Tuning disk storage for optimal performance
• Configuring your operating system for HTTP interception
• Forwarding Requests to other web caches
• Using redirectors to rewrite user requests
• Monitoring Squid with the cache manager and SNMP
• Using Squid to accelerate and protect HTTP servers
• Managing bandwidth consumption with Delay Pools

Product Details

ISBN-13:	9780596550530
Publisher:	O'Reilly Media, Incorporated
Publication date:	01/22/2004
Series:	Definitive Guides
Sold by:	Barnes & Noble
Format:	eBook
Pages:	466
File size:	3 MB

About the Author

Duane Wessels became interested in web caching in 1994 as a topic for his master's thesis in telecommunications at the Universityof Colorado, Boulder. He worked with members of the Harvest research project to develop web caching software. After the departure of other members to industry jobs, he continued the software development under the name Squid. Another significant part of Duane's research with the National Laboratory for Applied Network Research has been the operation of 6 to 8 large caches throughout the U.S. These caches receive requests from hundreds of other caches, all connected in a "global cache mesh."

Table of Contents

	Preface	xiii
1.	Introduction	1
	Web Caching	2
	A Brief History of Squid	3
	Hardware and Operating System Requirements	4
	Squid Is Open Source	5
	Squid's Home on the Web	5
	Getting Help	5
	Getting Started with Squid	7
	Exercises	8
2.	Getting Squid	9
	Versions and Releases	9
	Use the Source, Luke	10
	Precompiled Binaries	11
	Anonymous CVS	11
	devel.squid-cache.org	12
	Exercises	12
3.	Compiling and Installing	13
	Before You Start	13
	Unpacking the Source	14
	Pretuning Your Kernel	14
	The configure Script	18
	Make	27
	Make Install	29
	Applying a Patch	32
	Running configure Later	33
	Exercises	34
4.	Configuration Guide for the Eager	35
	The squid.conf Syntax	35
	User IDs	37
	Port Numbers	38
	Log File Pathnames	38
	Access Controls	39
	Visible Hostname	40
	Administrative Contact Information	42
	Next Steps	42
	Exercises	42
5.	Running Squid	43
	Squid Command-Line Options	43
	Check Your Configuration File for Errors	45
	Initializing Cache Directories	46
	Testing Squid in a Terminal Window	46
	Running Squid as a Daemon Process	47
	Boot Scripts	48
	A chroot Environment	50
	Stopping Squid	51
	Reconfiguring a Running Squid Process	52
	Rotating the Log Files	53
	Exercises	53
6.	All About Access Controls	54
	Access Control Elements	54
	Access Control Rules	78
	Common Scenarios	85
	Testing Access Controls	91
	Exercises	92
7.	Disk Cache Basics	93
	The cache_dir Directive	94
	Disk Space Watermarks	99
	Object Size Limits	99
	Allocating Objects to Cache Directories	100
	Replacement Policies	101
	Removing Cached Objects	102
	refresh_pattern	104
	Exercises	106
8.	Advanced Disk Cache Topics	108
	Do I Have a Disk I/O Bottleneck?	108
	Filesystem Tuning Options	110
	Alternative Filesystems	111
	The aufs Storage Scheme	112
	The diskd Storage Scheme	115
	The coss Storage Scheme	119
	The null Storage Scheme	122
	Which Is Best for Me?	122
	Exercises	123
9.	Interception Caching	124
	How It Works	124
	Why (Not) Intercept?	127
	The Network Device	130
	Operating System Tweaks	141
	Configure Squid	146
	Debugging Problems	148
	Exercises	151
10.	Talking to Other Squids	152
	Some Terminology	152
	Why (Not) Use a Hierarchy?	153
	Telling Squid About Your Neighbors	155
	Restricting Requests to Neighbors	159
	The Network Measurement Database	162
	Internet Cache Protocol	164
	Cache Digests	172
	Hypertext Caching Protocol	174
	Cache Array Routing Protocol	176
	Putting It All Together	178
	How Do I ...	182
	Exercises	183
11.	Redirectors	185
	The Redirector Interface	186
	Some Sample Redirectors	187
	The Redirector Pool	189
	Configuring Squid	190
	Popular Redirectors	192
	Exercises	193
12.	Authentication Helpers	194
	Configuring Squid	195
	HTTP Basic Authentication	195
	HTTP Digest Authentication	201
	Microsoft NTLM Authentication	204
	External ACLs	207
	Exercises	210
13.	Log Files	211
	cache.log	212
	access.log	215
	store.log	227
	referer.log	231
	useragent.log	232
	swap.state	233
	Rotating the Log Files	235
	Privacy and Security	236
	Exercises	236
14.	Monitoring Squid	237
	cache.log Warnings	237
	The Cache Manager	239
	Using SNMP	290
	Exercises	301
15.	Server Accelerator Mode	302
	Overview	303
	Configuring Squid	304
	Gee, That Was Confusing!	308
	Access Controls	310
	Content Negotiation	311
	Gotchas	312
	Exercises	314
16.	Debugging and Troubleshooting	315
	Some Common Problems	315
	Debugging via cache.log	319
	Core Dumps, Assertions, and Stack Traces	323
	Replicating Problems	326
	Reporting a Bug	329
	Exercises	329
A.	Config File Reference	331
B.	The Memory Cache	399
C.	Delay Pools	401
D.	Filesystem Performance Benchmarks	407
E.	Squid on Windows	418
F.	Configuring Squid Clients	421
	Index	433