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Infrastructure & Security Specialist specializing in Linux, VMware, Hyper-V, Windows Server, Oracle databases, infrastructure troubleshooting, security incident response, virtualization, and production systems support. I help businesses investigate security incidents, recover compromised Linux and WordPress environments, harden infrastructure, stabilize production systems, and resolve complex hosting, virtualization, and server issues. My experience includes: ✔ Security incident response & malware remediation ✔ WordPress malware removal & website recovery ✔ Server hardening & security auditing ✔ SSH, access control & authentication hardening ✔ VMware & Hyper-V virtualization ✔ Windows Server administration ✔ Linux systems administration ✔ Oracle Database administration & troubleshooting ✔ Infrastructure troubleshooting & performance analysis ✔ RAID, storage & recovery diagnostics ✔ VPS, dedicated server & hosting environments ✔ Backup & disaster recovery support ✔ PowerShell & Bash automation ✔ Email, DNS & server migrations ✔ Monitoring, stability & capacity planning Recent projects include security incident response and malware remediation across 155+ WordPress websites, Hyper-V VM scaling and performance stabilization, RAID recovery diagnostics on HPE servers, Linux/WHMCS migrations, Oracle environment troubleshooting, mail infrastructure troubleshooting, and production environment recovery. I focus on identifying root causes quickly, minimizing downtime, and delivering practical, production-ready solutions for critical systems and business infrastructure.

Network & IT Infrastructure Expert | Mikrotik | VPN | Linux | Cloud With 25 years of experience in IT infrastructure and network engineering, I specialize in designing, securing, and optimizing network systems for businesses of all sizes. Whether you need a reliable VPN solution, a secure network setup, or an optimized server infrastructure, I can help you achieve your goals efficiently. What I Offer: Mikrotik & Network Configuration – Routing, Firewall, VLANs, QoS, Wireless VPN & Secure Networking – WireGuard, OpenVPN, IPsec, GRE tunnels Linux System Administration – Ubuntu, CentOS, Debian, server automation Cloud & Backup Solutions – Veeam, Rsync, ZFS, Proxmox, Disaster Recovery Server & API Hosting – OpenStreetMap servers, self-hosted solutions Troubleshooting & Performance Optimization – Network monitoring, security hardening I have worked with businesses, startups, and enterprise clients to ensure their IT infrastructure is secure, scalable, and high-performing. My approach is straightforward – I analyze, optimize, and deliver solutions that just work. Let’s connect and discuss how I can help with your project!

Linux System Administrator and DevOps Engineer with hands-on experience supporting production environments, deployment automation, CI/CD pipelines, and enterprise infrastructure. Experienced with Linux server administration, Jenkins automation, Oracle-based environments, middleware support, and infrastructure troubleshooting in production systems. What I can help you with: Linux server administration (Oracle Linux, Ubuntu) CI/CD pipeline setup and maintenance Jenkins automation and deployment workflows Docker deployments Oracle & PostgreSQL administration WebLogic / GlassFish middleware support Infrastructure automation with Bash and Ansible Production troubleshooting and performance analysis Git / SVN administration and deployment workflows Nginx / Apache configuration Technologies: Linux, Oracle Linux, Ubuntu, Jenkins, Docker, GitLab CI/CD, Oracle Database, PostgreSQL, Bash, Ansible, Nginx, Apache, SVN, Git, WebLogic, GlassFish I focus on reliable infrastructure, stable deployments, fast issue resolution, and clear communication.

⚡️⚡️⚡️TOP rated IT Specialist⚡️⚡️⚡️ Need quick IT support or a reliable expert for long-term projects? Extensive background in system administration, server and network architecture, security, endpoint protection, and data center operations. Proven problem-solving skills and decisiveness enable effective direction and resolution of complex technical issues on a global scale, even under strict time constraints and budgetary limits. Assistance with securing IT environments (NIST, GDPR, NIS2, ISO 27001) or implementing infrastructure. Here are some feedback: - Excellent work. Very flexible and knowledgeable. - So strong skill and very quick to help me with my vpn setting on windows server with AD integration. Will work with him again and again. - Dejan's understanding of Windows Server Administration and AWS is amazing.. - Dejan, your knack for untangling Windows Group Policy and Domain issues saved our project. Top-notch work! - Executed quickly, highly responsive. Great experience and a true professional. - Windows server security - Very impressed with Dejan's work. Will hire him again. - Dejan was great expert and help us a lot. He gave us a whole picture and advice what to do next. Thank him a lot ! - Dejan was very responsive and supportive! He was willing to take up topics of research that were new/ unfamiliar and troubleshoot issues. I would definitely recommend him! - Very knowledgeable with VMWare, helped me get my server back online and added additional protections to prevent any further complications. Not to mention he was able to help with my situation right away! Will be hiring again with anything related to VMware. - Dejan made a great and fast troubleshoot for our Windows Server 2012 R2. He has a lot of knowledge and experience. Our problem was solved under 30 minutes.

I help SaaS teams ship production-ready .NET APIs, Azure microservices, and AI-integrated backends — on time, with zero surprises. Here's what I've delivered on Upwork: ✅ 13 projects completed with 100% Job Success Score ✅ REST APIs handling 1,000+ requests/day, saving one client 20 hours/week in manual work ✅ Migrated 20 legacy .NET Framework apps to .NET Core — zero downtime ✅ Built Python ETL pipelines on Databricks for enterprise analytics workflows ✅ Long-term engagements up to 1,100 hours with repeat clients What I work with: → Backend: C#, ASP.NET Core, .NET 6/7/8/9/10, Web API, Entity Framework, Dapper → Architecture: Microservices, Clean Architecture, Domain-Driven Design, CQRS → Cloud: Azure (App Service, Functions, DevOps, OpenAI Service), CI/CD pipelines → Data: SQL Server, Python, PySpark, Databricks, ETL → Frontend (when needed): Angular, JavaScript, React

System Engineer/ Cisco engineer for 10 years now. Proxmox master proffieciency and deploying Ceph clusters Linux master usage- Ubuntu,Centos,Gentoo Worked on administration of Windows machines from Xp to 10 now. NAS intermediate proficiency(QNAP expert, Synology and FreeNAS/Openmediavault intermediate) Cisco stenghts: Wireless(controller and access points), Voice(Callmanager,CallCenter, H.323 voice gateways), routing and switching(L3VPN,VLANs), security(ASA configuration)