linux centos cxfs file system raid network interface syslog iscsi postfix diagnostic analysis nmap vmstat access control selinux iptables technical support samba jira ext2 network file systems iostat management rsync netstat mysql logical volume manager cron cpio unmount android (operating system) ubuntu access control list installation mariadb information technology firewall linux server mpstat nagios gunzip nginx logging dynamic host configuration protocol (dhcp) dhcp snooping server administration scheduling process management troubleshooting zimbra