======UNIX Knowledge Assessment======

=====0x0=====
Given the following permission strings, what is the resulting octal permissions?

  * drwxr-x-w-
  * --w-rw---x
  * pr-xrw--wx
  * c-----x-w-
  * -r-x-wxrw-
  * drw-rw-r--

=====0x1=====
Based on the following:

<code bash>
val1=15
val2=1
</code>

What will the output be of each of the following, and why?

  * <nowiki>echo "${val1}+${val2}"</nowiki>
  * <nowiki>echo '$((${val1}+${val2}))'</nowiki>
  * <nowiki>val3=6; echo "${val1}${val3}"</nowiki>
  * <nowiki>yes | head -16 | wc -l</nowiki>

=====0x2=====
In **/var/public/unix/ka/** is a file called **ka1.mp3**; 
  * copy this somewhere in your home directory (how did you do this?)
  * figure out how to access its contents (how did you do this?)

=====0x3=====
For all files:
  * What is the file's name?
  * What type of file is it?
  * Can you view its contents? If not, how do you remedy this?

=====0x4=====
For any C (.c) files:
  * How do you successfully compile it?
  * How do you appropriately run it?
  * What does the program appear to do?


=====0x5=====
For any shell script:
  * What is the script's name?
  * What does it appear to do?
  * Using # marks for comments, add comments at the end of each line of uncommented script code, explaining as best you can what is going on
  * Upon running the script, what is the correct way to run it so it does something?

=====0x6=====
NOTE: If you cannot finish this one, it turns into a project.

In your speckled but hidden life of nefariousness and crime, you have managed to hack into the secure system of some organization. In this exploit, you obtained "hashfile", which has a list of user names and their encrypted passwords.

As you do not have the actual plaintext passwords, you cannot immediately log in. Remembering your time (well spent) taking a UNIX course before turning to your current life of debauchery, you decide to set about brute forcing these passwords.

Using the programs and scripts you otherwise obtained from **ka1.mp3**, rig up a brute force password cracker to determine what these users have for passwords.

You may work with the following assumptions:

  * Passwords are no longer than 3 characters
  * Passwords can contain ONLY lower- or upper-case letters, or numbers

Aside from determining the user passwords, please answer me the following:

  * Which user(s) have passwords that in some way mirror their user name?
  * Which user(s) have passwords that match that of a dictionary word?
  * What changes/modifications did you have to make to the various scripts to create a workable solution?
  * How many total password combinations can there be for 2 character upper/lower/number?
  * How many total password combinations can there be for 3 character upper/lower/number?
  * The **time** command can prepend a command on the command-line. How long does it take to generate all the possible 2 character passwords?
  * The **time** command can prepend a command on the command-line. How long does it take to generate all the possible 3 character passwords?

Challenge:

  * Once you have a working solution, see how much you can optimize your overall runtime (compare times from before) by pre-allocating a rainbow table, and altering the logic of these scripts to use that as input.