System and Network Administration

• Art of "keeping things running"
• Really the art of "managing complex systems and interactions".
• "... there's always a future in Computer Maintenance." (Frank Zappa, Deteriorada)
• "... don't pay any attention to that man behind the curtain." (the Wizard of Oz).
• "So important, that no one knows it's there."

Four parts of the course

• The machine: operating system basics.
• System administration: how to control machines.
• Network administration: how to build communities.
• Enterprise administration: how to support a mission.

The machine

• Files.
• Processes.
• Users.
• Daemons.
• Shells.
• Environments.

System Administration

• aiding users.
• building a system.
• maintenance and upgrades.
• security.
• troubleshooting and debugging.
• performance tuning.

Network Administration

• aiding users.
• providing connectivity.
• security.
• providing and managing network services.
• troubleshooting and debugging.
• capacity planning.

Enterprise Administration

• providing coherence.
• managing lifecycle.
• risk management.
• security.
• policy.
• monitoring.
• incident response.

My Personal Biases

• (and the key theme at most Sysadmin Conferences)
• Network administration is the art of connecting people, (and incidentally connecting their computers)
• Sound administration flows from reasoned policy decisions (regarding what is important and what isn't)
• My research: make policy decisions, once made, easier to enforce.

An old joke about the human element in networks

• the 9 layers of the OSI network reference model:

  number	name	interpretation
  1	Physical Layer	how devices are physically connected
  2	Data Link Layer	how neighboring devices communicate
  3	Network Layer	how non-neighboring devices communicate
  4	Transport Layer	how to avoid communication errors
  5	Session Layer	how devices managing ongoing communication
  6	Presentation Layer	how devices agree on the format of data
  7	Application Layer	how devices agree on the meaning of data
  8	Financial Layer	how devices agree on what to spend
  9	Political Layer	how devices agree on how to get money	you are here!

Nature of the profession

• Generalist - one must know a little about many things.
• Lifelong learning - one must know how to "find out" about almost anything that develops, including new technologies or new problems.
• People-centric - unlike the 'nerd' TV image in Level 9, administrators have to be good at dealing with people and handling complaints.

Common Illusions

• Not about power, but about responsibility.
• Not about superiority, but about synergy.
• Not about creativity, but about stability
• Not about job security, but about mission security.

Realities of the profession

• Thankless - most users are insensitive to the demands of the job.
• Legally risky - many managers happily ask admins to perform illegal acts. Recently "security" gurus have been sued for malpractice.
• Disorganized - constant interrupts from problems make it difficult to complete tasks.
• Politically complex - must often ask for money from superiors, and explain what it's for to technically unaware people.
• Limited advancement - must often change careers in order to advance in rank. All of my graduates who started as System Administrators ended up in software development or management.
• "So unimportant that -- the world would fall apart without it."
• You're most successful if no one notices that you're there.

Administration as a profession

• I don't expect that most of you are up to the task of being admins for life.
• But if you are, there are support organizations that you should join ASAP (discounts for students).
• Join the System Administrators' Guild (SAGE)
• Attend USENIX Conferences (apply to attend free as a student!)
• Apply for student internships and grants.
• I used to be the Tufts University student outreach coordinator and can help you apply for grants, scholarships, etc.

This course: UNIX-centric

• developed at AT&T Bell Labs and University of Calif. at Berkeley (UCB)
• many flavors:
  • System-V (AT&T SysV)
    • Solaris (Andante)
    • Dec OSF4/Compaq Tru64
  • Berkeley Standard Distribution (BSD)
    • SunOs (Solaris predecessor)
    • FreeBSD
    • NetBSD
    • BSDi (commercialization via Berkeley)
  • Linux (Linus Torvalds)
    • Sort of BSD
    • with SysV extensions
    • many flavors ('distributions'):
      • RedHat (choice for this course)
      • SuSE (Germany)
      • Slackware
      • Debian (GNU)

Why UNIX/Linux?

• You're already somewhat familiar with using it.
• It's freely available and runs on almost all PC's and Mac's.
• You can see what you're doing more easily than with Win-doze or Mac-us ( Concepts are the same in all three cases.

This course: three phases of empowerment

• Biggest complaint of former students: "didn't know enough UNIX to begin".

  part	theme	alternate interpretation
  I	becoming a 'power user'	getting dangerous to yourself
  II	becoming a 'super user'	getting dangerous to others
  III	becoming a 'network admin'	extending danger to the internet
  IV	becoming an architect	becoming a danger to a corporation

• More advanced students should see me about other options, including engaging in advanced research.

First Guiding Principle: RTFM

• "Read the manual"
• You can provide an appropriate "f-word" depending upon your mood.
• There's no way to 'learn everything'.
• This discipline is just too complex to keep in your head all at once.
• So if you excel at it, you'll be RTFM'ing every workday.
• Too big for any one book (see end of index to lecture notes).
• We'll rely very much on online documentation.
• "User manuals might as well be written in Greek" - popular commercial on teaching CD's for Windows.
• So we have to learn to read them, whatever language they're written in!

Unix documentation

• man pages: document different parts of UNIX.
• emacs info: GNU/FSF version of documentation (for those who wish emacs were the operating system).

Man pages

• On solaris (mezzo):
• man man: describes a particular command man
• man -k man: describes all man pages about man.
• man -s 3 time : describes the time function (in section 3) as opposed to the time command (in section 1).

Man sections

• 1: user commands.
• 2: system calls in C.
• 3: user functions in C.
• 4: file formats.
• 5: miscellaneous.
• 6: games.
• 7: devices and interfaces.
• 8: administrative commands.

Emacs Info

• Parallel to manual pages.
• control-H I invokes it.
• Simple hypertext mechanism.
• Can also run tkinfo on an X11 terminal.
• Gets very crowded because there's no mechanism for organizing large hierarchies efficiently.

Stuff only available in info

• Anything GNU/FSF claims as its own.
• Emacs documentation.
• gcc/g++ finer points.
• The theory was that emacs would replace UNIX/Windows/Macos as your operating system
• Then things would be easy (!)

Reality: emacs is a perk

• emacs isn't installed on many UNIX's by default.
• Must install it later.
• Almost all admins learn vi/ex to deal with systems without emacs.
• Real masters learn ed/sed as well.

This is just too big!

• Our systems are very complex.
• Thousands of commands.
• That interact with one another.
• Must learn to skim information efficiently.
• Start by skimming the books to find out what's in them.
• Best skill to have: strategic reading: read to solve problems, not to understand everything.