Linux

Part I   The Linux File Server Project

The first section of the site. Written for intermediate to advanced users who have just installed Linux on a server at home or in a small office and need to know more about connecting their Linux server to their home network. Topics covered include, basic troubleshooting and network management techniques, methods to make your Linux server become a file server for your Windows PCs, software installation tips and wireless connectivity.

 

CHAPTER 1

Why Host Your Own Site?

Network Diagram
Alternatives To Home Linux Hosting

In-House Web Server Management Considerations
Factors To Consider Before Linux Hosting Yourself
How To Migrate From An External Provider

 

CHAPTER 2

Introduction to Networking

What Is TCP/IP?
What Do IP Addresses Look Like?
What Is Localhost?
What Is A Subnet Mask?
How Many Addresses Do I Get With My Mask?
What's The Range Of Addresses On My Network?
What Is Duplex?
What Is A Hub?
What Is A Switch?
What Is A LAN?
What Is A Router?
What Is A Gateway?
What Is A Route?
What Is A Default Gateway?
What Is A NIC?
What Does The "Link" Light On My NIC Indicate?
What Is A MAC Address?
What Is ARP?
What Is A DTE?
What Is A DCE?
What Is A Straight Through / Crossover Cable?
What Is A Firewall?
What Is NAT?
What Is Port Forwarding With NAT?
What Is DHCP?
What Is DNS?
How Can I Check The IP Address For A Domain?
How Do I Get My Own DNS Domain Name?
What is FTP?
Where is Linux Help?
 

CHAPTER 3

Linux Networking

How To Configure Your NIC's IP Address

How To Change Your Default Gateway

How Configure Two Gateways

How To Delete A Route

How To View Your Current Routing Table

How To Change The Duplex Setting Of Your NIC

How To Convert Your Linux Server Into A Router

Configuring Your /etc/hosts File

How to configure your NIC for DSL and cable modem Internet connections

 

CHAPTER 4

Simple Network Troubleshooting

How To See Your ARP Table

Doing Basic Cable and Link Tests
Testing Your NIC
How to See MAC Addresses
Using ping to Test Network Connectivity
Using telnet to Test Network Connectivity
Testing Web sites with the curl and wget Utilities
The netstat Command
The Linux iptables Firewall
Using traceroute to Test Connectivity
Using MTR To Detect Network Congestion
Viewing Packet Flows with tcpdump
Viewing Packet Flows with tethereal
Basic DNS Troubleshooting
Using nmap
Determining the Source of an Attack
Who Has Used My System?
 

 

CHAPTER 5

Troubleshooting Linux With Syslog

syslog

The /etc/syslog.conf File
Activating Changes to the syslog Configuration File
How to View New Log Entries as They Happen
Logging syslog Messages to a Remote Linux Server
Syslog Configuration and Cisco Network Devices

Logrotate

The /etc/logrotate.conf File
Sample Contents of /etc/logrotate.conf
The /etc/logrotate.d Directory
Activating logrotate
Compressing Your Log Files

syslog-ng

The /etc/syslog-ng/syslog-ng.conf file
Installing syslog-ng
Configuring syslog-ng Clients

Simple syslog Security
Conclusion

 

CHAPTER 6

Installing RPM Software

Where To Get Commonly Used RPMs
How to Easily Access CD RPMs With Automount
Getting RPMs Using Web Based FTP
Getting RPMs Using Command Line Anonymous FTP
Getting RPMs Using WGET
Automatic Updates With yum
Automatic Updates With Up2date
How To Install The RPMs
How to Install Source RPMs
RPM Installation Errors
How To List Installed RPMs
How To List All The Files Inside An RPM
How Uninstall RPMs
Which RPMs Will Start Up At Boot Time?
 

CHAPTER 7

The Linux Boot Process

The RedHat Boot Sequence

Determining The Default Boot runlevel

Get A GUI Console Without Changing runlevels

Get A Basic Text Terminal Without Exiting The GUI

Switching runlevels on the fly

How To Set Which Programs Run At Each runlevel

 

CHAPTER 8

Configuring A Linux DHCP Server

Download & Install The DHCP Package

The /etc/dhcp.conf File

Upgrading Your DHCP Server

How to get DHCP started

Modify Your Routes for DHCP on Linux Server

Configuring Linux clients to use DHCP

Error Found When Upgrading From Redhat 7.3 To 8.0

 

CHAPTER 9

Adding Linux Users And Sudo

Who Is The Super User?

How To Add Users

How To Delete Users

How To Tell The Groups To Which A User Belongs

How To Change Your Password

What is sudo?

Download & Install The sudo Package

The visudo command

The /etc/sudoers File

How To Use sudo

Using syslog To Track All sudo Commands

 

CHAPTER 10

Configuring Samba

Download and Install Packages
How To Get SAMBA Started
The Samba Configuration File
How SWAT Makes Samba Simpler
Creating A Starter Configuration
Fine Tuning The Configuration
How To Create A Samba PDC Administrator User
How To Add Workstations To Your Samba Domain
How To Add Users To Your Samba Domain
Domain Groups And Samba
How To Delete Users From Your Samba Domain

 

CHAPTER 11

Sharing Resources with Samba

Adding A Printer To A Samba PDC

Creating Group Shares in SAMBA

Windows Drive Sharing With Your SAMBA Server

 

CHAPTER 12

Samba Security & Troubleshooting

Testing The smb.conf file
Samba and Firewall Software - iptables, Zone Alam, Windows XP Firewall
Testing Basic Client / Server Network Connectivity
Testing Samba Client / Server Connectivity
Checking the Samba Logs
Samba Network Troubleshooting
Basic Samba Security

 

CHAPTER 13

Linux Wireless Networking

Wireless Linux Compatible NICs
Common Wireless Networking Terms
Networking With Linux Wireless-Tools
Configuring 802.11g with Linux Incompatible NICs (With an NDIS wrapper example)

Compiling ndiswrapper
Networking With Linux-WLAN
Linux-WLAN Preparation

Installing The Linux-WLAN Drivers

Post Installation Steps

Linux-WLAN Encryption For Security

Troubleshooting Your Wireless LAN
Wireless Networks In Businesses
Conclusion

Linux

CHAPTER 14

Linux Firewalls Using iptables

What Is iptables?

Using iptables as part of your web server management security plan
Download And Install The Iptables Package
How To Get iptables Started
Packet Processing In iptables
Iptables Packet Flow Diagram
Processing For Packets Routed By The Firewall
Packet Processing For Data Received By The Firewall
Packet Processing For Data Sent By The Firewall
Targets And Jumps
Descriptions Of The Most Commonly Used Targets
Important Iptables Command Switch Operations
General Iptables Match Criteria
Common TCP and UDP Match Criteria
Common ICMP (Ping) Match Criteria
Common Match Extensions Criteria
Using User Defined Chains
Sample iptables Scripts

    Basic Initialization

    Allowing DNS Access To Your Firewall

   Allowing WWW And SSH Access To Your Firewall

   Allowing Your Firewall To Access The Internet

   Allow Your Home Network To Access The Firewall

   IP Masquerade

      Regular Masquerading (Many to One Network Address Translation)

      Port Forwarding Type NAT

      Static NAT

   Logging & Troubleshooting
 

CHAPTER 15

Configuring a Linux FTP server

FTP Overview

Problems with FTP and firewalls

How To Download And Install The VSFTP Package

How To Get VSFTP Started

Testing To See If VSFTP Is Running

What Is Anonymous FTP?

The /etc/vsftpd.conf File

FTP Security Issues

 

CHAPTER 16

Telnet, TFTP and XINETD

Telnet

TFTP

 

CHAPTER 17

Secure Remote Logins & File Copying

Using Secure Shell As A Replacement For Telnet

Testing To See If SSH Is Running

The etc/ssh/sshd_config File

Using SSH To Login To A Remote Machine

What You Should Expect To See When You Log In

Deactivating Telnet once SSH is installed

Using SCP as a more secure replacement for FTP

Copying files using SCP without a password

 

CHAPTER 18

Configuring DNS

What Is DNS?

What Is BIND?

How DNS is critical to Web Hosting

When To Use A DNS Caching Name Server

When To Use A Regular DNS Server

How To Download & Install The BIND Packages

How To Get BIND Started

Configuring A Caching Name Server

Configuring A Regular Name Server

DHCP Considerations For DNS

 

CHAPTER 19

Dynamic DNS

What Is DNS?

What Is Dynamic DDNS?

Dynamic DNS And NAT Router/Firewalls

Dynamic DNS Prerequisites

Installing And Using ez-ipupdate

Installing And Using DDclient

Testing Your Dynamic DNS

 

CHAPTER 20

Web Hosting With The Apache Web Server

Preparation Before Configuring Apache

Download & Install The Apache Package

How To Get Apache Started

Configuring DNS For Apache

General Configuration Steps

File Permissions And Apache

Single IP Address - Two Sites

Apache Running On A Server Behind A Firewall

How To Protect Web Page Directories With Passwords

Issues When Upgrading To Apache 2.0

 

CHAPTER 21

Configuring Linux Mail

Configuring Sendmail

How Sendmail Works
Installing Sendmail
Starting Sendmail
How To Restart Sendmail After Editing Your Configuration Files
The /etc/mail/sendmail.mc File
Configuring DNS for sendmail
How To Configure Linux Sendmail Clients
Converting From a Mail Client to a Mail Server
The /etc/mail/relay-domains File
The /etc/mail/access File
The /etc/mail/local-host-names File
Which User Should Really Receive The Mail?
Sendmail Masquerading Explained
Using Sendmail to Change the Sender's Email Address
Troubleshooting Sendmail

Fighting SPAM

Using Public SPAM Blacklists With Sendmail
Spamassassin
A Simple PERL Script To Help Stop SPAM

Configuring Your POP Mail Server

Installing Your POP Mail Server

Starting Your POP Mail Server
How To Configure Your Windows Mail Programs
Configuring Secure POP Mail
How to handle overlapping email addresses.
Troubleshooting POP Mail

 

CHAPTER 22

Monitoring Server Performance

 

(See Chapter 23 for advanced MRTG Topics)

SNMP

What is SNMP?
Doing SNMP Queries
SNMP on a Linux Server
SNMP On Other Devices
Different SNMP Versions

MRTG

What is MRTG?

How MRTG Helps With Web Server Management
A Typical MRTG Server Bandwidth Graph
Download and Install The MRTG Packages
MRTG Differences Between Fedora and RedHat 9
Configuring MRTG
Configuring Apache To Work With MRTG
Using MRTG To Monitor Other Subsystems
Troubleshooting MRTG
Fedora Core 1 MRTG Errors With Net-SNMP
Indexmaker MRTG_LIB Errors With RedHat 9 and 8.0
Precedence Bitwise Error With RedHat 9

Webalizer

What Is Webalizer?
How To View Your Webalizer Statistics
The Webalizer Configuration File
Make Webalizer run in Quiet Mode

TOP
VMSTAT

 

CHAPTER 23

Advanced MRTG (CPU, Memory, Disk and TCP Connections Monitoring)

Locating And Viewing The Contents Of MIBs
Differences In MIB And MRTG Terminology

The CPU And Memory Monitoring MIB
The TCP/IP Monitoring MIB

Manually Configuring Your MRTG File

Parameter Formats
Legend Parameters
Options Parameters
Title Parameters
Scaling Parameters
Defining The MIB Target Parameters

Comparing Two MIB Values

Mapping MIBs To The Graph Legends
Plotting Only One MIB Value
Adding MIB Values Together For a Graph
Sample Target: Total CPU Usage
Sample Target: Memory Usage
Sample Target: Newly Created Connections
Sample Target: Total TCP Established Connections
Sample Target: Disk Partition Usage
Defining Global Variables

Implementing Advanced Server Monitoring

A Complete Sample Configuration
Testing The Configuration
Creating A New MRTG Index Page To Include This File
Configuring CRON To Use The New MRTG File
 

CHAPTER 24

Configuring NTP

What is NTP?

Download & Install The NTP Package

The /etc/ntp.conf File

How To Get NTP Started

Determining If NTP Is Synchronized Properly

Configuring Cisco Devices To Use An NTP Server

Firewalls and NTP

 

 

Linux

CHAPTER 25

Network Based Linux Installation

Setting Up The Installation Server
Creating Boot Diskettes
The Network Installation
Troubleshooting The Network Installation
Automating Installation With Redhat Kickstart

 

CHAPTER 26

Linux Software RAID

RAID Types
Before You Start
Configuring Software RAID

 

CHAPTER 27

Expanding Linux Partitions With LVM

LVM Terminologies
Configuring LVM Devices

 

CHAPTER 28

Managing Disk Usage With Quotas

Setting Up Quotas
Other Quota Topics
 

CHAPTER 29

Remote Disk Access With NFS

Installing NFS
How To Get NFS Started
The /etc/exports File
Activating Modifications The Exports File
NFS And DNS
Configuring The NFS Client
Other NFS Considerations

 

CHAPTER 30

Centralized Linux Logins With NIS

Scenario
Configuring The NIS Server
Configuring The NIS Client
Adding New NIS Users
Configuring The NIS Client
 

CHAPTER 31

Centralized Linux Logins With LDAP And RADIUS

The LDAP Database Structure
Scenario
Configuring The LDAP Server
Configuring The LDAP Client

 

CHAPTER 32

Controlling Web Usage With Squid

Download and Install The Squid Package
The /etc/squid/squid.conf File
Configuring Web Browsers To Use Your Squid Server
How To Get Squid Started
Squid And Firewalls
Squid Disk Usage
Troubleshooting Squid
Other Squid Capabilities

 

CHAPTER 33

Modifying The Kernel To Improve Performance

Download and Install The Kernel Sources Package

Kernel Modules
Creating A Custom Kernel
Updating GRUB
Creating A Boot Diskette For The New Kernel
Updating The Kernel Using RPMs

 

CHAPTER 34

Basic MySQL Configuration

Installing MySQL
Starting MySQL
A Common Fedora MySQL Startup Error
The Location of MySQL Databases
Creating a MySQL "root" Account
Accessing The MySQL Command Line
Creating and Deleting MySQL Databases
Recovering Your MySQL Root Password
MySQL Granting Privileges to Users
MySQL Database Backup
MySQL Database Restoration
Very Basic MySQL Network Security

 

Chapter 35

Linux VPN Configuration

Installing and configuring Openswan and /or FreeS/WAN

 

APPENDIX I

Miscellaneous Topics

Linux Security With TCP Wrappers
Adjusting Kernel Parameters
Running Linux Without A Monitor
Make Your Linux Box Emulate A VT100 Dumb Terminal
VPN Terminologies
TCP/IP Packet Format
ICMP Codes

 

APPENDIX II

Codes, Scripts & Configurations

Subnet Calculator Script
Apache File Permissions Script
Sendmail SPAM Filter Script
IPtables Basic Initialization Script
IPtables Firewall As A Webserver Script
IPtables IP Masquerading Script
IPtables Port Forwarding Script
IPtables Complex script
DNS Zone File For my-site.com
DNS Zone File For my-other-site.com
Forward Zone File For A Home Network Using NAT
Reverse Zone File For A Home Network Using NAT
Sendmail Sample /etc/mail/access File
Sendmail Sample /etc/aliases File
Sendmail Sample /etc/mail/local-host-names File
Sendmail Sample /etc/mail/sendmail.mc File
Sendmail Sample /etc/mail/virtusertable File
 

APPENDIX III

Differences Between The Fedora Versions

FTP Differences
DHCP Differences
DNS Differences
Routing Differences
Iptables Differences
Software Installation Differences
Wireless Networking Differences

 

APPENDIX IV

Configuring Syslog On Cisco Devices

Cisco Routers

Catalyst CAT Switches running CATOS

Cisco Local Director

Cisco PIX Filewalls

Cisco CSS11000 (Arrowpoints)

The Sample Cisco syslog.conf File
 

 

BIBLIOGRAPHY

Bibliography - Links Page

Wireless Linux

Cisco Router Configuration Examples

Cisco PIX Firewall Configuration Examples

Netfilter - iptables Configuration

General Home Networking Resource Pages

SSH Servers and SSH Clients

The Windows SCP client called WinSCP

FTP Server and FTP Clients

DHCP Server

Apache Web Server Software

Sendmail Mail Configuration

Dynamic DNS - Hosting Your Website at Home

Static DNS

NTP Server

POP Mail Server Software

Samba - Linux as a Windows File Server

General Linux Resource Pages

Disk Partitioning

Network Monitoring

My Other Sites

Cisco

CHAPTER I

Configuring Cisco PIX Firewalls

Network Address Translation (NAT)

Accessing the PIX command line

Sample PIX Configuration: DSL - DHCP

How To Get Static IPs For DSL Cheaply

Sample PIX configuration: DSL - Static IPs

 

CHAPTER 2

Configuring Cisco DSL Routers

An Introduction to Network Address Translation (NAT)

Introduction to accessing the router command line

Sample Configurations

Other NAT Topics

 

CHAPTER 3

Cisco SOHO VPNs

Cisco router VPN configuration example

Cisco PIX VPN configuration example

 

APPENDIX I

Cisco Syslog Configurations

Cisco Routers

Catalyst CAT Switches running CATOS

Cisco Local Director

Cisco PIX Filewalls

Cisco CSS11000 (Arrowpoints)

The Sample Cisco syslog.conf File
 

APPENDIX II

Cisco Configurations

Cisco PIX Firewall - DHCP DSL Configuration

Cisco PIX Firewall - Static DSL Configuration

Cisco PIX permanent site to site VPN configuration example.

Cisco PIX VPN configuration for Windows clients such as Cisco EasyVPN.
 

APPENDIX III

Bibliography - Links Page

Cisco Router Configuration Examples

More Cisco PIX Firewall Configuration Examples

MISC

Chapter 1

Network Device Backups with Rancid

Rancid Installation
Initial Rancid Configuration
Rancid File Locations
The Rancid router.db file
The Rancid .clogin.rc file
Testing Rancid
Testing A Login for a Single Device
Testing For All Devices
Troubleshooting Using the Rancid Log Files
Getting Rancid Help
Conclusion

WP1

Chapter 1

Why Relocate Your Web Site?

When to Migrate From Virtual Hosting
When to Migrate Between Data Centers
Factors That Affect Virtual and Self-Hosting
How to Analyze Migration Costs

Potential Increased Profits
Net Changes in Monthly Expenses
Capital Outlays

Conclusion

 

Chapter 2

Preparing for Server Relocation

Data Center Selection Criteria
Planning the Logistics of Relocation

Coordination Preparation
Customer Communications Preparation
Server Area Preparation
Network Preparation
Server Preparation
DNS Preparation
Transportation Preparation

Conclusion

 

Chapter 3

Post Relocation Activities

Activities During the Relocation
Post Relocation Activities
Conclusion

 

Appendix I

Relocation Check Sheets

Data Center Rating
Cost Justification Work Sheet
Coordination Preparation Check Sheet
Customer Communication Check Sheet
Server Area Preparation Check Sheet
Network Preparation Check Sheet
Server Preparation Check Sheet
DNS Preparation Check Sheet
Transportation Preparation Check Sheet
Activities During the Relocation Check Sheet
Post Relocation Check Sheet
Individual Server Worksheet
Post Mortem Analysis Sample Form

 

Appendix II

How to Choose a Data Center ISP

Data Circuit Pricing

Data Circuit Types

IP Address Ownership

Routing Protocols

Border Gateway Protocol

Determining a BGP Autonomous System Number

Administrative Tasks Needed to Advertise BGP Routes

Conclusion

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