Page 215 - DCAP602_NETWORK_OPERATING_SYSTEMS_I

Unit 11: User Accounts

other examples notes

You can view a comprehensive list of /etc/sudoers file options by issuing the command man
sudoers.
using syslog to track all sudo commands

All sudo commands are logged in the log file /var/log/messages which can be very helpful in
determining how user error may have contributed to a problem. All the sudo log entries have the
word sudo in them, so you can easily get a thread of commands used by using the grep command
to selectively filter the output accordingly.
Here is sample output from a user bob failing to enter their correct sudo password when issuing
a command, immediately followed by the successful execution of the command /bin/more
sudoers.

[root@bigboy tmp]# grep sudo /var/log/messages
Nov 18 22:50:30 bigboy sudo(pam_unix)[26812]: authentication failure; logname=bob
uid=0 euid=0 tty=pts/0 ruser= rhost= user=bob
Nov 18 22:51:25 bigboy sudo: bob : TTY=pts/0 ; PWD=/etc ; USER=root ; COMMAND=/
bin/more sudoers
[root@bigboy tmp]#

Note It is important to know how to add users, not just so they can log in to
our system. Most server based applications usually run via a dedicated unprivileged
user account, for example the MySQL database application runs as user mysql and the
Apache Web server application runs as user apache. These accounts aren’t always created
automatically, especially if the software is installed using TAR files.

Finally, the sudo utility provides a means of dispersing the responsibility of systems management
to multiple users. You can even give some groups of users only partial access to privileged
commands depending on their roles in the organization. This makes sudo a valuable part of any
company’s server administration and security policy.

11.1.8 user and super user

Linux puts a lot of power at your fingertips. That’s the best reason to switch to Linux; it’s also
the most dangerous thing about the system. Linux controls how much power you can use on the
computer based on your Login ID. It keeps a database of all users, and it keeps track of which
user owns which files, and which users have permission to view, edit, and execute each file,
folder or program. An ordinary user will not be able to do really dangerous things, like editing
the user database, or deleting every file on the system.
But right now you are logged in as root. You are not just an ordinary user, you are SuperUser.
(SuperUser is a real Unix term, synonymous with root.) There are no restrictions on your power.
You have the ability to crash the system and make it otherwise unusable in more ways than you
can imagine. As a novice it is very easy to make your system completely unusable with a single
erroneous command. Believe me. I speak from experience. The first weekend after I installed
Linux, I had to reinstall it FOUR times before I finally got smart and quit destroying it. And I’m a
pretty savvy guy around computers, so don’t think you’re immune just because you know your
way around a PC.

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