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Unix Admin pt 1, Day 2
Goals
In this session you will:
- learn how to simplify your keyboarding life...
- learn how to control permissions and workgroups
- Learn how to handle common user requests
- learn how to schedule tasks
- learn how to backup your system
- learn startup and shutdown procedures
Review
POST
- What file generally holds information about users, their passwords, etc? Where is it located? Take a peek at it to remind yourself what it looks like.
- How is it delimited (ie, how are the fields separated)? What are the fields and what do they mean?
- What is a shadow passwd system? How can you tell if your system uses one.
- In what file would you find group definitions?
- What command might one use to add a new user? To delete a user? What if there is no scripts for either of these activities? Would it be possible to do the job manually?
Simplifying your life at the keyboard
- learn your editor (vi, emacs, etc)
- learn your shell (bash, csh, etc) and it's functions like command history and filename completion
- use screen!
screen -d detach
screen -r re-attach
- Ctrl-a Ctrl-c: create a new window
- Ctrl-a Ctrl-n: go to next window
- Ctrl-a Ctrl-p: go to previous window
- Ctrl-a Ctrl-[number]: go to that window number
- Ctrl-a Ctrl-A: name the window
- Ctrl-a Ctrl-w: get list of windows
- Ctrl-a Ctrl-k: kill the current window
- Ctrl-a Ctrl-S: Split window
- Ctrl-a Ctrl-?: get help
groups and permissions
- the truth about files: all files are have one owner and one group
- the truth about users: all users are exactly one user at a time, but they can belong to many groups at one time.
Danger! |
usernames and group-names can look alike but they are not the same1. Burn this into your noggin... |
group control
- groups can have passwords
- the user can be in many groups at once
- some systems require the user to
newgrp in order to be in that group. You change back to your default group by issuing newgrp with no argument.
skelfiles and umask
It is traditional for an admin to prepare skeleton files that will be copied to the user's directory at the time of account creation...
communicating with the user
echo Everybody log off now! The building is on fire! | wall
- keep
/etc/motd updated
talk user
USER REQUESTS: I can't log in!
tail -f your auth.log.
- unknown user error indicates improper username
- password error indicates wrong pass. Case?
- no mention may indicate they are hitting another machine
USER: I can't get my email!
- check logfiles
- log into pop server on port 110
- check for pop.lock
- reset pass
USER: I forgot my password!
Reset it, and give them a good one.
USER: Can you look at this script and see why it doesn't run?
Warning! Warning!
Post your schedule if necessary.
TACTICAL: forcing good passwords
- Crack your own passwd files...
- run it regularly, from a cronjob
Homework
Please read the following sections:
- top 283
- rebooting p.127-33
- filesystems and structure pp.50-53
- find pp72-76
- tar pp478-480
- networks 585-650
http://www.mousetrap.net/syllabus/admin_unix_pt1/day2.html
$Id: day2.orb,v 1.5 2002/02/11 02:22:19 mouse Exp $
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© 1994-2002 jason carr.
distributed under the terms of the GNU Free Documentation License.
jason carr
Reminders
- Classroom temperature can be wildly variable. Dress lightly and bring layers.
- your username is based on the class title and the last two digits of your workstation's hostname.
- remember to take your work with you.
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