Andrii K.

I focus on building reliable systems and enjoy digging into complex issues — including performance tuning, disaster recovery, root cause analysis, and problems that aren't always straightforward. With 20+ years in system administration, DevOps, and infrastructure engineering, I work with both legacy systems and modern environments — from bare-metal servers to virtualized and containerized environments. 𝗧𝗵𝗲𝗿𝗲 i𝘀 𝗮 𝗹𝗼𝘁 𝗼𝗳 𝗔𝗜 𝗵𝗲𝗿𝗲 𝘁𝗵𝗲𝘀𝗲 𝗱𝗮𝘆𝘀, 𝗺𝗲𝘀𝘀𝗮𝗴𝗲 𝗺𝗲 𝗳𝗼𝗿 𝗮 𝗿𝗲𝗮𝗹 𝗰𝗵𝗮𝘁. 🚀 Key areas: • Infrastructure planning, setup, and migrations (bare metal ↔ VM ↔ cloud) • Troubleshooting and performance tuning (high CPU/load, slow systems, bottlenecks) • Email deliverability (SPF, DKIM, DMARC, spam issues, warmup, mail server reputation restoration) • Virtualization and containerization (VMware, Proxmox, KVM, Docker) • Networking and VPN solutions • Disaster recovery, backup strategies, malware cleaning, compromise investigation, and finding attack vectors • Long-term systems support and maintenance 🔧 Core Expertise • OS: FreeBSD, Linux (CentOS, AlmaLinux, Rocky, RHEL, Ubuntu, Debian, Gentoo), Windows, Windows Server • Virtualization: VMware vSphere, ESXi, Proxmox, KVM, oVirt, VMware Workstation, VirtualBox • Containers & Automation: Docker, Docker Compose, Jenkins, Ansible • Web: Nginx, Apache, LiteSpeed, Tomcat, Lighttpd, Caddy • Databases: MySQL, MariaDB, PostgreSQL, MongoDB • Mail systems: Postfix, Dovecot, Courier Cyrus, Rspamd, Postgrey, PostfixAdmin, SquirrelMail, Roundcube, SPF, DKIM, DMARC, MTA-STS, AWS SES, Mailgun, Sendy • Control panels: WHM/cPanel, VestaCP, Virtualmin, Cyberpanel, and so on 🔐 Networking & VPN • WireGuard, AmneziaWG, Xray, 3x-ui, OpenVPN, StrongSwan, tinc, mpd5, IPSec, L2TP, IKEv2 • BGP (Quagga), Squid (including LDAP and Kerberos auth), DNS (BIND, dnsmasq), DHCP, TFTP • Fail2ban, iptables, ipfw, pf, csf 💾 Storage & Backup • TrueNAS Core/Scale, FreeNAS, SAN (iSCSI), ZFS, AWS S3, Backblaze, Wasabi • Veeam Backup & Replication, XSI Backup, rsync, rsnapshot, rclone 🛠 Legacy Systems & Industrial Equipment Support • Migration and virtualization of legacy systems (DOS, Windows 3.x/9x/NT/2000) • Running outdated software on modern hardware via virtualization • Recovering systems from an old working HDD to a VM if native hardware fails. Including industrial PCs. ⚙️ Other • Samba3 + LDAP, Samba4 (NT4 and AD domain analogs), LDAP, domains up to 500 users, GPO, roaming profiles. • Monitoring: Zabbix, Prometheus, Grafana • Services: Memcache, Redis, OpenLDAP, NFS, SVN, Git, GitLab (self-hosted), FTP, SFTP • Platforms: Moodle, Nextcloud, OnlyOffice, BigBlueButton, DAViCal, WordPress, Magento, Home Assistant, HAOS, ESPHome • Remote management: AnyDesk, TeamViewer, Radmin, Ammyy Admin, RustDesk, MeshCentral • Hardware: Dell, HP, Supermicro servers, Dell PowerVault storages • Networking equipment: HP, Dell, 3Com switches • Embedded/firmware: DD-WRT, OpenWRT (including software cross-compiling for ARM on x86_64). Arduino, ESP32 DIY projects. • Scripting: Shell scripting, Python, PHP I value long-term collaboration and quality over quick fixes. Have an interesting or unusual problem? That's exactly what I enjoy — feel free to reach out.