solid knowledge in:
.- Linux (Redhat, CentOS, Suse, debian, ubuntu, etc)
.- VMWare
.- Web (Apche, Tomcat, Jboss), DNS, SMTP, LDAP, NFS, NTP, SVN, DHCP, SNMP, Syslog Server, SMB, openvpn, NAT, SQUID, PostgreSQL, MySQL, Proxy Web
.- Services and servers monitor
.- Scripting Programming perl, shell, etc.
.- Web application developer in php - postgres / mysql