Unix for Advanced Users

2. Logging In

• 2.1. Who is watching for logins
  2.1.1 On serial ports: the getty process
  2.1.2 On networks: the inetd/in.telnetd processes
  2.1.3 On networks: the sshd process
  
• 2.2. The process controlling logins: /bin/login
• 2.3. Who is permitted: /etc/passwd, /etc/shadow, and /etc/group
  2.3.1. What is /etc/passwd?
  2.3.2. What is /etc/shadow?
  2.3.3. What is /etc/group?
  
• 2.4. Where am I now: The login shell
• 2.5. The dotfiles
• 2.6. Common problems when logging in:
  2.6.1. An unreachable machine
  2.6.2. An absent service or a disabled account
  2.6.3. A bad shell or a botched dotfile
  2.6.4. /etc/shells (ftp)