Learning With Nitin Kumar

Example Scenario:1 Objective : You want to visit www.example.com . Entering the URL : You type www.example.com into your browser’s address bar and hit Enter. DNS Resolution : Step 1 : Your browser checks if it has the IP address for www.example.com cached from a previous visit. If not, it sends a DNS request to your router. Step 2 : Your router, which may have its own DNS cache, checks if it has the IP address. If not, it forwards the DNS request to your ISP’s DNS server or a public DNS service like Google’s (8.8.8.8). Step 3 : The DNS server looks up www.example.com and returns the IP address, let’s say 93.184.216.34 , back to your router. Step 4 : Your router forwards the IP address to your browser. Making the HTTP Request : Step 1 : Your browser now knows the IP address of www.example.com , so it creates an HTTP request to 93.184.216.34 asking for the webpage. Step 2 : The HTTP request is sent from your device with private IP  192.168.1.2  with source port  10001 ...

  Private Network Definition: A private network is a network that is restricted to a specific group of users or devices. It is not accessible from the public internet and is typically used for internal communication and resource sharing within an organization or home. A private network is a network used within a specific organization, home, or other closed environment. It is not directly accessible from the public internet. It is designed to allow secure communication and resource sharing among devices that are part of the network. Characteristics: Accessibility : Accessible only by authorized users within the network. It is isolated from external networks. Security : Generally more secure because it is not exposed to the broader internet. Security measures like firewalls, VLANs, and access controls are commonly used. IP Addressing : Uses private IP address ranges defined by standards (e.g., RFC 1918) that are not routable over the internet. Private IP Address Ranges: 10.0.0.0 to...

  Definition: A VPN is a service that creates a secure, encrypted connection over a less secure network, such as the internet. It allows users to send and receive data as if their devices were directly connected to a private network. Key Features: Encryption : Encrypts data to protect it from eavesdropping. Authentication : Verifies user identity before granting access. Remote Access : Allows users to access internal network resources from remote locations. Workflow Example: Remote User Connection : User Setup : An employee working remotely installs a VPN client on their laptop or mobile device. Connection Initiation : The user opens the VPN client and connects to the company's VPN server. Authentication and Encryption : Authentication : The VPN server verifies the user's credentials (e.g., username and password). Encryption : The VPN client establishes an encrypted tunnel between the user's device and the VPN server. Accessing Resources : Internal Network Access : Once co...

Configuration: SNMP-based monitoring of  RHEL VM   Here are the detailed steps to monitor a RHEL (Red Hat Enterprise Linux) VM via SNMP using Zabbix: 1. Install SNMP and SNMP Utilities on RHEL VM:  First, you need to install the SNMP and SNMP utilities on your RHEL VM sudo yum install net-snmp net-snmp-utils net : Short for network, indicating the tools are network-related. snmp : Simple Network Management Protocol, the protocol used for network management. utils : Short for utilities, meaning the package contains various tools and programs for SNMP. 2. Configure SNMP on RHEL VM:  Edit the SNMP configuration file: sudo vi /etc/snmp/snmpd.conf Add or modify the following lines to configure SNMP: # Map the community name "public" into a "security name" com2sec notConfigUser  default       public # Map the security name into a group name group   notConfigGroup v1            notConfigUser group  ...

S nmpwalk is a versatile tool that simplifies the process of retrieving and discovering SNMP data. Snmpwalk is a command-line utility used to retrieve a subtree of management values from a network device using the Simple Network Management Protocol (SNMP). Used to retrieve information from network devices using the Simple Network Management Protocol (SNMP). Why Use snmpwalk ? 1. Discovering Available OIDs:  SNMPwalk   helps discover the available Object Identifiers (OIDs) on a network device. This is useful for understanding what metrics and data are accessible through SNMP. Command: snmpwalk -v 2c -c public 34.30.100.68 This command will output all OIDs available on the device with the IP 34.30.100.68 , along with their values. -v 2c :  This option specifies the SNMP version to use. In this case, 2c stands for SNMP version 2c, which is a common version that supports community-based security. -c public :  This option specifies the SNMP community string, which acts...

The ITIL (Information Technology Infrastructure Library) process is a set of best practices for delivering IT services. ITIL provides a systematic and professional approach to the management of IT service provision. It provides guidance for managing IT infrastructure, development, and operations, helping organizations to align their IT services with their business needs. Key Components of ITIL Service Strategy : Defines the perspective, position, plans, and patterns that a service provider needs to execute to meet an organization's business outcomes. Service Portfolio Management Financial Management for IT Services Demand Management Business Relationship Management Service Design : Converts service strategy into a plan for delivering business objectives. Service Catalogue Management Service Level Management Capacity Management Availability Management IT Service Continuity Management Information Security Management Supplier Management Service Transition : Develops and improves capab...

What is PagerDuty? PagerDuty is a tool that helps businesses respond quickly to problems with their software or hardware systems. PagerDuty is a tool that helps companies quickly handle IT issues and system problems.  How Does PagerDuty Work? Integration with Monitoring Tools : PagerDuty connects to other tools that monitor your systems, like Zabbix, Datadog, or New Relic. These monitoring tools check if your servers, applications, or websites are working properly. Incident Detection : When a monitoring tool detects a problem (like a server going down), it sends an alert to PagerDuty. Alerting : PagerDuty takes this alert and notifies the right person or team. Notifications can be sent via email, SMS, phone calls, or mobile app push notifications. On-Call Schedules : PagerDuty helps you manage who is on call (available to respond to issues) at different times. You can set up schedules and escalation policies, so if the first person doesn't respond, the alert goes to the next person...

 On local host: 1. Generate key :ssh-keygen -t rsa -b 2048 2. Copy the public key from file: /root/.ssh/id_rsa.pub On Remote server: 1. Paste it into the file: /root/.ssh/authorized_keys 2. Edit the file: /etc/ssh/sshd_config PasswordAuthentication no ChallengeResponseAuthentication no 3. Restart the sshd service   sudo systemctl restart sshd