Unit 4

This unit on creating users and groups in Linux cleared up some of my previous confusion about user permissions. For the moment, I have written down the permissions given by each number on a post-it and displayed it prominently next to my monitor.
1 = execute only
2 = write only
3 = write and execute
etc.

The text spent several pages going over the importance of encrypted passwords stored in the shadow file and the security risk posed if a user's password is easily guessed, e.g. "password." What jumped out to me was that some programs will allow the user to create a long password, but will only remember the first 8 characters. I have on occasion jumbled the last couple letters in a password and still been granted access to my account. Now I have some idea why that works, although I could not predict which programs do this or not.

In order to install Webmin this week and practice adding users using a GUI via web browser, I had to install Perl which turned into a long frustrating search for a typo.

The file I needed was libmd5-perl_2.03-1_all.deb whereas I had been been omitting the "d."

Week 2:

This week consisted of using the virtual private network (vpn) and virtual network computing (vnc) to remotely gain control of a computer running Ubuntu 10.04. From there, I spent most of my time going over the tutorials on command lines and putting them into the command line interface (cli) or terminal. The easy part of this was getting the VPN and VNC running. Those posed no problem to me. The tricky part was getting the CLI to do what I wanted.


Using "cd" to move up and down the directories in the terminal was fine. It helps to navigate and figure out the maze of /home/user1/folders/etc or going back to the root / then navigating to /usr/share/example-content. Then ls, cp, mv, rm, mkdir, and file all worked as expected. I rejoiced. The "less" command gave me problems. In theory, this should allow me to view text files in a readable format, but all I got was gobbledygook. Since I have installed Ubuntu on my hard drive as a virtual machine, I will continue to experiment with less and see if I can't figure out what is going wrong.

The most confusing part of this week's tutorials is ownership and permissions. Logging in as the Super User, I can change the permissions of a file with chmod, chgrp, and chown. So a file which is rwxrwxrwx is readable, writable, and executable by the owner, the group, and others. So, I see how in binary 111 makes something rwx or 101 makes it r-x. What gives me trouble is that
100 = 4

101 = 5

110 = 6

111 = 7
For the time being, I think I'll be sticking to an alphabetical approach i.e. chmod a+rwx