There are plenty of open source control panels on the market, and Webmin is another very popular option. Webmin is basically a combination of a web server that uses a range of CGI apps to automatically update system files such as “/etc/inetd.conf” and “/etc/psswd”. Web hosts like the fact that Webmin is highly modular, there are literally hundreds of additional add-ons that you can install to make sure that you can control additional apps on their Linux OS.
Some of the features you get out of the box with Webmin include the management of user accounts including groups and quotes. You can also do the expected management of DNS services alongside management of SAMBA file sharing.
Webmin gives you full control over all the usual server services including web, FTP, mail, SSH and DHCP alongside OpenLDAP management and the option to manage proxy services. You can also manage a range of virtual systems ranging from Xen to OpenVZ and KVM.