Creating a Dial-Up Connection with the Internet Configuration Wizard..................197
Launching Your PPP Connection ............................................................................199
Launching Your PPP Connection on Demand ..........................................................199
Checking Your PPP Connection ..............................................................................200
Checking That Your Modem Was Detected..............................................................200
Connecting to the Internet with Wireless................................................................201
Summary ................................................................................................................202
Chapter 6: Securing Linux . . . . . . . . . . . . . . . . . . . . . . . . . 203
Linux Security Checklist..........................................................................................204
Finding Distribution-Specific Security Resources ....................................................207
Finding General Security Resources ........................................................................208
Using Linux Securely ..............................................................................................209
Using Password Protection ......................................................................................209
Choosing Good Passwords ......................................................................................210
Using a Shadow Password File ................................................................................211
Breaking Encrypted Passwords ......................................................................212
Checking for the Shadow Password File ........................................................212
Using Log Files ........................................................................................................213
The Role of syslogd..................................................................................................216
Redirecting Logs to a Loghost with syslogd..............................................................216
Understanding the messages Log File ......................................................................217
Using Secure Shell Tools..........................................................................................218
Starting the ssh Service ............................................................................................218
Using the ssh, sftp, and scp Commands ..................................................................219
Using ssh, scp, and sftp Without Passwords ............................................................220
Securing Linux Servers ............................................................................................222
Controlling Access to Services with TCP Wrappers..................................................222
Understanding Attack Techniques ..........................................................................225
Protecting Against Denial of Service Attacks ............................................................226
Mailbombing ................................................................................................226
Spam Relaying ..............................................................................................228
Smurf Amplification Attack............................................................................228
Protecting Against Distributed DOS Attacks ............................................................229
Protecting Against Intrusion Attacks ........................................................................233
Evaluating Access to Network Services ..........................................................233
Disabling Network Services ..........................................................................235
Securing Servers with SELinux ................................................................................236
Protecting Web Servers with Certificates and Encryption ........................................237
Symmetric Cryptography ..............................................................................237
Asymmetric Cryptography ............................................................................238
Secure Sockets Layer ....................................................................................238
Using Linux Live CD Security Tools ........................................................................247
Advantages of Security Live CDs..............................................................................247
Using INSERT to Check for rootkits ........................................................................247
Summary ................................................................................................................248
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