I have experience setup/troubleshoot in these area:
OS: Windows, Ubuntu, Debian, CentOS, MacOS
Web Server: Apache, NGINX, Varnish
Hosting ControlPanel: cPanel/WHM, Webmin, Plesk, SolusVM, WHMCS
Mail Server: Postfix, Sendmail, Exim
WebMail: Squirrelmail, RoundCube
Database Server: MySQL, Postgresql
FTP Server: ProFTP, vSFTP
VPN Server: OpenVPN
Virtualization: KVM, OpenVZ, VBox
Cloud: AWS, DigitalOcean, Linode, Archipel, OpenNebula
Monitoring Server: gwOS, Nagios, Icinga, xymon
Firewall: iptables, CSF
SCM: SVN, GitLab
Server Shared: NFS, Samba, Glusterfs
DNS Server: BIND, djbdns
DNS Management: NicTool, VegaDNS, Route53
Load balancing: AWS LoadBalance, pound
MailServer Solution: iRedMail, Zimbra
Orchestration Engine: Ansible, Puppet, Vagrant, Terraform
Ticketing: RT, Kayako, RedMine