added linux

Author: imShakil

interview-guides/API/01-rest-api-vs-mqtt.md

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+# How do REST and MQTT differ in real-time communication?
+
+- REST: stateless, client-server model, suitable for CRUD APIs.
+
+- MQTT: lightweight pub/sub protocol, ideal for real-time, low-bandwidth environments like IoT.
+
+Use MQTT when low latency and continuous messaging are needed, e.g., sensors or real-time device updates.

interview-guides/aws/01-nodejs-in-aws.md

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+# How would you deploy a Node.js app using AWS services?
+
+- Use EC2 for hosting, or Lambda for serverless.
+- Store data in DynamoDB or RDS.
+- Use ALB/ELB for load balancing.
+- Use CloudWatch for logging and monitoring.
+- Automate with CloudFormation or CDK.

interview-guides/git/01-fork-vs-clone.md

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+# How would you secure an MQTT connection?
+
+- Use TLS to encrypt traffic.
+- Implement authentication (username/password or token).
+- Set ACLs (Access Control Lists) for topic-level permissions.
+- Deploy behind reverse proxy with rate-limiting.

interview-guides/pub-sub/01-mqtt.md

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+# Create a Custom Apache User
+
+> Create a user named `moyna` and Assign a unique UID `1949` and designate the home directory as `/var/www/moyna`.
+
+<details>
+<summary> Solution </summary>
+
+    sudo adduser -d /var/www/moyna -u 1949 moyna
+
+</details>

linux/01.md

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+# Execute Permission
+
+After conducting a security audit within the Stratos DC, the Nautilus security team discovered misconfigured permissions on critical files. To address this, corrective actions are being taken by the production support team. Specifically, the file named /etc/resolv.conf on Nautilus App 2 server requires adjustments to its Access Control Lists (ACLs) as follows:
+
+1. The file's user owner and group owner should be set to root.
+2. Others should possess read only permissions on the file.
+3. User mark must not have any permissions on the file.
+4. User eric should be granted read only permission on the file.
+
+## Steps
+
+1. Login into App server
+2. Set owner and group to `root`:
+
+    ```sh
+    sudo chown root:root /etc/resolv.conf
+    ```
+
+3. Set others `read only`:
+
+    ```sh
+    sudo chmod o=r /etc/resolv.conf
+    ```
+
+4. Remove all permission for user `mark`
+
+    ```sh
+    sudo setfacl -m u:mark:--- /etc/resolv.conf
+    ```
+
+5. Give user `eric` read-only permission:
+
+    ```sh
+    sudo setfacl -m u:eric:r-- /etc/resolv.conf
+    ```
+
+6. Verify Results:
+
+    ```sh
+    ls -la /etc/resolv.conf
+    getfacl /etc/resolv.conf
+    ```
+
+    ```shell
+    [root@stapp02 ~]# ls -la /etc/resolv.conf
+    getfacl /etc/resolv.conf
+    -rw-r--r--+ 1 root root 69 Aug 11 05:26 /etc/resolv.conf
+    getfacl: Removing leading '/' from absolute path names
+    # file: etc/resolv.conf
+    # owner: root
+    # group: root
+    user::rw-
+    user:mark:---
+    user:eric:r--
+    group::r--
+    mask::r--
+    other::r--
+    ```

linux/02.md

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+terraform {
+  backend "remote" {
+    workspaces {
+      name = ""
+    }
+
+    organization = "value"
+  }
+
+  required_version = "1.12.1"
+
+  required_providers {
+    aws = {
+        source = "hashicorp/aws"
+        version = "6.2.0"
+    }
+  }
+  
+}

projects/terraform/aws/main.tf

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+
+variable "region" {
+    default = "ap-southeast-1" 
+}
+
+variable "instance_type" {
+    default = "t3.small"  
+}
+
+variable "ssh-key" {
+    
+  
+}