linux and windows system administrator

J KARTHIK

System Administrator

**************@*****.*** +91-978******* linkedin.com/in/karthik-j-2aa003303 Bangalore, India

PROFESSIONAL SUMMARY

Results-driven Linux and Windows System Administrator with 4+ years of hands-on experience in server provisioning, virtualization, web hosting, and 24/7 infrastructure support. Currently engaged in freelance system administration, providing independent consulting and remote infrastructure management for clients. Proven ability to diagnose and resolve complex system issues, implement proactive monitoring strategies, and maintain high availability across multi-client environments. Adept at collaborating with cross-functional teams and delivering consistent performance in rotational shift operations.

TECHNICAL SKILLS

Operating Systems

Linux (RHEL, CentOS, Debian, Ubuntu),

Windows Server (2012 / 2016 / 2019 / 2022)

Scripting & Automation

Bash / Shell Scripting, PowerShell, CRON Job Scheduling

Virtualization

KVM, OpenVZ, VMware vSphere / ESXi, Hyper-V, OnApp (SolusVM & Virtualizor)

Web Hosting Panels

cPanel / WHM, Plesk, DirectAdmin, CentOS Web Panel (CWP)

Windows Administration

Active Directory (AD DS), Group Policy (GPO), DNS, DHCP, IIS, RDS, File & Print Services

Monitoring Tools

Zabbix, PRTG Network Monitor

Backup & Recovery

Acronis Backup, JetBackup, FTP-based Backup, Disaster Recovery Procedures

Database Administration

MySQL (Install, Optimize, Repair, Dump & Restore)

Security

IPTables, SSH Hardening, SSL/TLS Certificate Management, DDoS Mitigation

Mail Servers

Exim Mail Server Configuration and Troubleshooting

Networking

TCP/IP, DNS, DHCP, VPN, Firewall Rules, IPTraf

Ticketing & Chat Tools

WHMCS, HostBill, Request Tracker (RT), LiveChat, Gajim

Version Control

Git, GitHub

Troubleshooting

Boot Repair, RDP Issues, Network Diagnostics, Event Viewer, RSAT, Performance Monitor

PROFESSIONAL EXPERIENCE

Freelance System Administrator April 2025 – Present

Self-Employed, Madurai (Remote)

Linux & Windows Administration

•Provided remote Linux and Windows Server administration support to clients, covering end-to-end server setup, OS patching, and security hardening across RHEL, Ubuntu, and Windows Server environments.

•Resolved critical issues including boot failures, disk corruption, RDP connectivity problems, and service outages, minimising client downtime.

•Configured and maintained user accounts, permissions, and Group Policy Objects (GPO) for small business Active Directory environments.

Web Hosting & cPanel Support

•Migrated client websites across cPanel/WHM and Plesk environments, including DNS zone configuration, SSL certificate deployment, and email account setup.

•Troubleshot email delivery failures on Exim; configured and validated SPF, DKIM, and DMARC records to improve deliverability.

•Administered Apache and Nginx web servers, resolving 5xx/4xx errors and optimising virtual host configurations.

Monitoring, Backup & Security

•Deployed Zabbix monitoring for small-scale infrastructure; configured custom alerting thresholds, dashboards, and notification channels.

•Implemented automated backup schedules using JetBackup and rsync-based scripts; documented and tested disaster recovery procedures.

•Hardened client servers with SSH key-based authentication, IPTables firewall rules, and fail2ban intrusion prevention.

Virtualization

•Assisted clients in provisioning and managing KVM and VMware virtual machines, optimising CPU, RAM, and storage resource allocation.

•Performed VM snapshot management and template creation to streamline deployment workflows.

Linux Server Administrator November 2021 – April 2025

Nixserv IT Solutions Pvt Ltd, Bangalore Clients: Flipperhost, Sparkstation, iomart, Genx

Linux Server Administration

•Provisioned, configured, and maintained secure Linux servers (RHEL, CentOS, Ubuntu, Debian) in production and new-build environments.

•Managed disk additions, partition creation, and file system administration (ext4, XFS, LVM).

•Diagnosed and resolved boot failures using IPMI remote console access and rescue/single-user mode.

•Scheduled and automated recurring tasks using CRON jobs, reducing manual intervention.

•Installed, configured, and managed the Exim Mail Server, including queue management and deliverability troubleshooting.

•Configured and managed SSL/TLS certificates on standalone and panel-based servers to enforce domain security.

•Managed complete server lifecycle: load monitoring, software installation, patching, and updates.

Windows Server Administration

•Deployed and administered Windows Server 2012/2016/2019 environments, including AD DS, DNS, DHCP, and Group Policy Objects (GPO).

•Created and managed Active Directory user accounts, security groups, and role-based access control (RBAC) policies.

•Configured and maintained IIS for web application hosting, including SSL bindings and application pool management.

•Managed Remote Desktop Services (RDS) and enforced Group Policy to standardise desktop environments.

•Performed Windows patch management and maintained system health using Windows Server Update Services.

•Monitored Windows infrastructure performance using PRTG, addressing alerts proactively to prevent outages.

•Administered file shares, NTFS permissions, and print services across Windows Server environments.

Virtualization & Cloud Infrastructure

•Deployed and managed KVM and OpenVZ virtual machines; performed resource upgrades/downgrades (CPU, RAM, storage) using SolusVM and Virtualizor.

•Administered VMware, including VM provisioning, snapshots, and template management.

•Managed Hyper-V virtual machines and configured virtual switches and storage integration.

•Provided technical support for OnApp platform: resolved virtualization, storage, and networking issues, managed OS templates, and configured automated VM backups and disaster recovery.

•Monitored and optimised hypervisor performance in OnApp to ensure consistent VM uptime.

Monitoring, Backup & Security

•Installed and configured Zabbix monitoring for server health, alerting, and performance trending across Linux and Windows environments.

•Configured PRTG Network Monitor for bandwidth, CPU, memory, and service availability monitoring.

•Performed regular system backups and disaster recovery procedures using Acronis and JetBackup.

•Hardened servers by configuring IPTables firewall rules, SSH key-based authentication, and implementing DDoS mitigation strategies.

•Coordinated with data centre teams for hardware-level support, including correspondence for DC-related assistance.

Ticketing & Client Support

•Managed and resolved client tickets in RT (Request Tracker), ensuring timely resolution and closure within defined SLA intervals.

•Delivered 24/7 technical support in rotational shifts, collaborating with cross-functional teams and reporting to Shift Admin leads.

•Maintained detailed documentation of OnApp configurations, network topologies, performance reports, and usage metrics.

EDUCATION

B.E. – Electronics and Communication Engineering 2019

Bharath Niketan Engineering College, Theni

HSC – Higher Secondary Certificate 2013

T.M.H.N.U. Matriculation Higher Secondary School, Theni

SSC – Secondary School Leaving Certificate 2011

T.M.H.N.U. Matriculation Higher Secondary School, Theni

DECLARATION

I hereby declare that all the information provided above is true and accurate to the best of my knowledge.

Place: Bangalore (Karthik J)

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