I have years of experiences in Linux and Asterisk. Linux System Administration) Configuration of Linux servers including RedHat, CentOS, Ubuntu, SuSE distribution, monitoring tools(rrdtool, mrtg, nagios, snmp, cacti, munin), VPNs(OpenVPN, n2n VPN, PPTP), mail(sendmail,imap, pop3), DNS(bind), web server(apache+php), firewall(iptables,fail2ban), etc. Database) Database(MySQL, Oracle, IBM/DB2) install, configuration and management, built MySQL HA cluster. Virtualization) Virtualization platform(Citrix Xen Server, Vmware vSphere/ESX) install, configuration, physical to virtual(P2V). Amazon EC2/S3 configuration. Web Application) Web application for LAMP(phpbb,drupal,joomla,wordpress,etc..) install, migration between two different hosting provider. Asterisk) - FreePBX/Elastix/IncrediblePBX - A2Billing