A Technical I.T./DevOps Blog
Background
Facebook’s engineering culture during its earlier days of rapid growth was “move fast and break things.” But the Harvard Business Review says that this era is over.
Problem scenario
You are concerned about recommended practices and “best practices.” You want to be productive and leave no security gaps in your systems that you design/install or allow bugs in your code.
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Continue reading “What are Recommended Practices vs. “Best Practices”?”
Problem scenario
You are trying to run a hadoop command (to kick off a mapreduce job). But you get this error:
“Exception in thread “main” java.nio.file.AccessDeniedException: /home/jdoe/./mapper.py”
What should you do?
Solution (short version)
Change to a directory where the user can write files to. Retry the command.
Solution (long version)
Create a directory that is owned by the user and the group associated with the user that is running this command.
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Question
You have seen the word “hacker” appear in different contexts. You have seen it used to describe a cybercriminal. Moreover some companies proudly claim that they employ no hackers while only hiring trained software developers. In some articles the term hacker has a positive connotation. What is a hacker?
Answer
“Hacking tends to be a misunderstood topic, and the media likes to sensationalize,
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Problem scenario
You know that cross-site scripting (aka XSS) attacks are a big concern in today’s world. OWASP places XSS security risks as the seventh biggest web application risk as of June 2020. What are some techniques to stop such attacks from happening when designing a website that uses JavaScript?
Possible Solution #1
Have the HTML and JavaScript validate and escape regularly throughout the code.
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Continue reading “What Are Some Ways to Prevent XSS Attacks with a Web Page That Uses JavaScript?”
Problem scenario
In AWS you find some components, such as a Security Group, has an owner. You cannot find the owner in IAM. How do you learn more about this user?
Solution
The owner is not an IAM user. In the AWS Console, go to Support -Support Center. Search for the owner number there. You may have different account aliases.
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Continue reading “How Do You Find the Owner of an AWS Resource?”
Problem scenario
You are using Ansible with -vvv to see what Python version it is using. (Or you use ansible –version.) You see an incorrect version of Python being used.
You tried ansible_python_interpreter=/usr/bin/python3 in your playbook and in the ansible.cfg file. Neither worked.
What should you do?
Solution
In the playbook, find the hosts stanza. Underneath it use this (where python3 is the version you want and “/usr/bin” is the path to it):
vars:
ansible_python_interpreter: /usr/bin/python3 …
Continue reading “How Do You Change the Version of Python that Ansible Uses?”
Problem scenario
You have a VPC. You want a NACL to protect your VPC from hackers and other networks. What do you do?
Solution
Network ACLs are created by default when you create a VPC. They can be configured the same way Security Groups are configured in the AWS Console. Go to the VPC Dashboard -Security -Network ACLs. Click on the relevant Network ACL.
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Problem scenario
You have a Mac and want to copy heavily-formatted text from a web page or Excel spreadsheet into TextEdit. But you do not want the formatting to come with it. How do you do this?
Solution
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Continue reading “How Do You Paste Copied Content without the Formatting Using a Mac?”
Problem scenario
When grepping a file or output, you get “Binary file (standard input) matches”. You only see a subportion of the matching strings. What should you do?
Solution
Use the -a flag. Here is an example:
cat foobar.txt | grep -a coolterm
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Problem scenario
You try to run an Ansible playbook, but you get an error like this: “msg: Aborting target uses selinux but python bindings (libselinux-python) aren’t installed!”
You are using a Red Hat derivative of Linux (e.g., Red Hat Enterprise Linux, CentOS or Fedora) and Python 3. What should you do?
Solution
Prerequisite
Install pip3. If you need assistance,
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Continue reading “How Do You Fix the Ansible Problem about “libselinux-python”?”