CPSC 489/589-010 DevOps Spring 2024

Week 4 Class 8 Thu Feb 08 Posted: Feb 08

After Class

• Crossword answers that I did not specifically mention in class:

  • /usr/include Location of official include files
  • /usr/local/include Location of non-official include files
  • pipe The symbol "|" in a shell is the __ symbol

Announcements

• Project 1

• Diceware

  • Important to remember that these are not any words. They are words randomly chosen from a specific dictionary.
  • Use a separator between the words. Do not run them all together, as that is much more difficult to remember, and is less secure.
  • If the 6-word diceware password is not secure enough for you, add another word to your password.
  • 12.9 bits of entropy per word

• SSH Public Key

  • Your public key is the entire contents of the file id_ed25519.pub, including the prefix of ssh-ed25519 and the suffix with your username or comment. Make sure you entered the complete key in the form.
  • When directed to provide a specific type of SSH key, create that type. E.g., I did not ask for an RSA key.
  • Do not create the .ssh directory yourself. Let ssh-keygen do that. Why? You need to create things with the proper permissions. If you use mkdir to create the directory, you have to look up what permissions to make it. If you let ssh-keygen create it, then it uses the proper permissions.
  • Use defaults of commands such as ssh-keygen, especially when you are first using the command. Some of you did not use the default key filenames, and the ones you created are non-standard and not particularly good.

Agenda

• Exercise 17: Entropy

  This exercise is optional for CPSC 489 students, but required for CPSC 589 students.

  Write a 1 page PDF that explains the relationship between the number of words in a Diceware password, the number of bits of entropy, and the estimated time it would take to break the password. For the estimated times, provide a reference or the calculation used.

  End the paper with an argument for what length of Diceware password to use.

  Upload the paper to Brightspace. This is due by 11:59:59 on Thu Feb 15.

• Notes: Linux Accounts
• Exercise 18: Linux Accounts Crossword

• Exercise 19: Login

  If you provided your SSH Public Key before the due date, your key is installed in your account on the devops server.

  Your username is the your UA id (email without the @uakron.edu, e.g., jdoe1@uakron.edu has the account name jdoe1

  The devops server IP address is on Brightspace.

  1. Shell into the devops server using your account
  2. Change your local (gecos) information using the command chfn Requires password, so wait on this step.
  3. Log out

• Exercise 20: DevOpsComplexity CMake II

  Follow along and duplicate my changes to the CMake for the DevOps Complexity program.

  DevOpsComplexityCMake

All exercises are due by 4:30 pm on Fri Feb 09