Using Linux at Northern Michigan University

Northern Michigan University

• Regional University• Normal quality

students– Some great– Some struggle

• About 9,000 students and 200 majors

• Have some money

NMU’s Computers

• Every student gets a laptop– We load them with Java, C++, PuTTY– We haven’t had success with VNC– We may not load them with Linux

• We have a Laboratory– Kinda silly with all the laptops– Great for system admin class

Advantages of Linux

• Source code available– But it’s huge– Parts are interesting

• System very inspectable– Can see what’s happening inside

System Admin Class

• Teach Basic Linux Admin– Incoming students typically juniors– Lots of students from CIS, a few from the

town– Assume students don’t know nothin’

• Frustrates some students• Works for others

Goals of System Admin Class

– Add/del users– Networking (NFS, Samba, YP, net printing)– Compile the kernel– Become YP/NIS server and client– Taste shell and perl programming– Independent learning

– DEBUGGING SKILLS ARE VITAL

Pride of Ownership

• Everyone gets their own computer

• They install everything on it

• When it breaks, it’s their fault.

Fences Make Good Neighbors

• Get a firewall between your lab and the world.– Leave access to the departmental server– Deny access to the world– Files are forced to move through the

departmental server

Teach How to Debug

• Break their computers for them.

• Give a lousy error message.

• Give points for fixing the problems.

• Everyone gets a unique problem set.

Never Let Students Hack Each Others Computer!!!!!

The Problem List

Points: 10Task: Fix telnetting to euclid ----Points: 15Task: I cannot ping Euclid ----Points: 5Task: What is your ethernet hardware (mac) address? ----

Task: Fix telnetting to euclid Cause: add "198.110.193.8 euclid euclid.nmu.edu" to /etc/hosts ----Task: I cannot ping Euclid Cause: Add the line 'exit' to the script /etc/rc.d/init.d/network ----Task: What is your ethernet hardware (mac) address? Cause: Just ask

No Cheating (kinda)

• Don’t let students keep backup copies of /etc

Grading is Important

• Don’t use a dumb grading scheme.

• If you give points for labs…– Then assignments will be 0% or 100%

• You must use tests and broken-labs too.

Operating System Class

• Students are seniors.

• Goals are OS algorithms, not too much code.

Using Kernel Source

• Don’t make them compile kernels.• Do show them code.

– Size– Grep for “stupid”.

• 106 stupids, 32 of the “other” word

– Show easy parts• Old scheduler• Read syscall

Kernel Size

Top is Interesting

Strace is Interesting

• strace /bin/ls– Uses 119 syscalls– Open 21 files!!!!!!– Writes 3 times.

– Goal: Give a real picture for how things work

Benchmarking

• Easy to make a benchmark

• Time consuming to run them

• Whole class can do one run

• Always experimental error

Benchmarking Ideas

• Compile time vs RAM

• Read time vs read size– Never get to disk performance

• Which is faster, open or read?

Independent Study

• Linux inspires kids.

• Source code is available

• Lots of tools

• Linux is new– There are projects to be done.– Can effect the world!

Linux Benchmarking Project

• Three kids

• Is the kernel bloated and slow?– Compare new and old kernels– Count lines– Use lmbench

• Teacher was interested, too!

Benchmarking Results

• Experimental Errors Experienced.– Teamwork errors too!

• Email from Linux, Alan Cox, etc.

• Article on Slashdot

• Speech at Argonne National Lab.

• Professional Recognition

Unexpected Learning

• Army comes to arrest fellow prof– They were very nice people.– Student interest in security soars.– Learning happened– ACS is angry

Unexpected Learning (cont)

• We shutdown campus.net– And a business in California– Students suddenly interested in our

connectivity– Internet law became interesting too.

Conclusion

• Good Teaching is good teaching!– Need to be enthused.– Need to be hands-on.– Need to show examples.

Linux Helps with Teaching

• Showing code examples.

• Inspect a running system