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100 Days of DevOps Complete Writeup

·2 mins·
Mahir
Author
Mahir
I poke at code, dig into security, and write down whatever I learn along the way.
Table of Contents
  • This is/will be a complete writeup of the 100 Days of DevOps program from KodeKloud.
  • The KodeKloud platform uses various users, servers etc within their infrastructure for challenges. I will be writing a guide based on the content I get for the challenges and yours may be different. As a result, Day 1 has a writeup of a general command blocks for understanding. Should you wish to follow along, change the details as need be.

Day 1: Linux User Setup with Non-Interactive Shell
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Solution
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SSH into the server:

ssh user@server

Create the user using the command:

sudo useradd -m -s /usr/sbin/nologin username
  • -m creates a home directory

The **nologin** shell is a special type of shell in Linux designed to prevent a user from logging in interactively .

Day 2: Temporary User Setup with Expiry
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Task:
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Create a user named jim on App Server 1 in Stratos Datacenter. Set the expiry date to 2024-02-17, ensuring the user is created in lowercase as per standard protocol.

Solution
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1 SSH into the server:

ssh tony@stapp01.stratos.xfusioncorp.com

Create the user:

sudo useradd -m -e 2024-02-17 jim

Verify the entry:

cat /etc/passwd

Day 3: Temporary User Setup with Expiry
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Task:
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Following security audits, the xFusionCorp Industries security team has rolled out new protocols, including the restriction of direct root SSH login.
Your task is to disable direct SSH root login on all app servers within the Stratos Datacenter.

Solution
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SSH into the server:

ssh tony@stapp01.stratos.xfusioncorp.com

Change PermitRootLogin to no:

1. Open the file:

sudo vi /etc/ssh/sshd_config

2. Find the line you need:

  • Press /
  • Type PermitRootLogin
  • Press Enter

3. Enter edit mode:

  • Press i (insert mode)

4. Edit the text:

  • Use arrow keys to move around
  • Delete characters with Backspace
  • Change yes to no

5. Exit edit mode:

  • Press Escape

6. Save and quit:

  • Type :wq (colon, w, q)
  • Press Enter

Then restart SSH:

sudo systemctl restart sshd

Repeat the process for the other 2 App Servers

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