6. Users, groups and security

6.1. DES, MD5, and Crypt

6.2. S/Key

6.2.1. Secure connection initialization

6.2.2. Insecure connection initialization

6.2.3. Diversion: a login prompt

6.2.4. Generating a single one-time password

6.2.5. Generating multiple one-time passwords

6.2.6. Restricting use of UNIX passwords

6.3. Kerberos

6.3.1. Creating the initial database

6.3.2. Making it all run

6.3.3. Creating the server file

6.3.4. Populating the database

6.3.5. Testing it all out

6.3.6. Adding su privileges

6.3.7. Using other commands

6.4. Firewalls

6.4.1. What is a firewall?

6.4.2. What does IPFW allow me to do?

6.4.3. Enabling IPFW on FreeBSD

6.4.4. Configuring IPFW

6.4.5. Example commands for ipfw

6.4.6. Building a packet filtering firewall