• Installing and Implementing Linux
• Maintaining and Supporting Linux
• Passwords
  • Early versions of UNIX kept encrypted passwords in /etc/passwd file
  • Most versions now keep passwords in shadow file (only accessible to root)
  • UNIX uses one-way hash algorithm (Crypt)
  • Some newer versions using MD5
  • Encrypted password is 11 characters with a 2-character salt
• Unix Commands
• Access Control is managed through file permissions (rwx for owner, group, and everyone)
• inetd - Internet standard services daemon; /etc/inetd.conf is the main configuration file that lists all of the services and which are active; new versions of Linux place the daemons in a folder /etc/xinent.dd with the configuration in /etc/xinentd
• netstat - program which provides information about the network on which the host is running
  • Run netstat –r. Describe what is in the routing table.
  • Run netstat –i. Describe what is in the interface table. Where else could you get this information?
  • Run netstat –a.
    • List the active connections.
    • List the Internet servers
  • Run netstat –N. How does it compare to netstat –a?
  • Run netstat –s.
  • How many TCP packets had to be retransmitted? Should we be concerned?
  • Are there more UDP packets sent or received? Explain why.
• su and suid - su (super-user) is the root or administrative account; A program with suid permissions runs as root without the user have root privileges (ex. /usr/bin/passwd)

Please mail any comments about this page to summers_wayne@ColumbusState.edu