A young and pretty Linux server OS that takes a bit of work
Zentyal 2: like Ubuntu, with bits on
Despite repeated attempts, in testing, we couldn't get the network-gateway functionality running. It's nowhere near as automated as the other two – you have to use the dashboard to install DHCP and DNS servers, but the former would not start for us. Reinstalling as a standalone server worked fine, though, and gave us easy access to the server from its IP address. Ordinary HTTP access leads to a placeholder web page, whereas using HTTPS goes to the login screen for the dashboard interface. This is easier than with either SME Server or ClearOS; for both of them, we had to nip off to Google to find the magic address.
Once our test server was up and running, everything ran smoothly. We could easily add a group, put some users in it, add a file share, set the group's permissions over it, and with that, clients could attach and start putting files in the share. There's no equivalent of SME Server's i-bays or ClearOS's flexi-shares: here, file, web or FTP shares are all managed separately. Zentyal does have an interesting feature of its own, though: "network objects". These are collections of workstations, specified by IP address or other criteria, that can be managed as one – for instance for setting download restrictions.
As with both its rivals, a fair bit of the capabilities of a Zentyal server relate mainly to its use as a firewall, and if you don't make it the gateway, all of this becomes irrelevant. Some of the remaining functions do still work but are of questionable use, such as internal-LAN-only webmail.
Oops, you deleted the server
Zentyal lacks the level of integration of the others – there are no options to create default home pages or set up email file drop-boxes here. Zentyal gives you a web server, but managing it is up to you, for instance. The interface lacks polish in places, too – for example, there is an inconspicuous "save changes" field at the top right of the header area, which you must click after making some (but not all) settings changes. Even though it changes from green to bright red when something needs saving, it's not obvious, as your attention is on the main form. So, for instance, when entering the test account password to register one of our test servers, once the change "took", we instinctively clicked the button that appeared underneath. This wasn't "proceed" or "OK", which were represented by the "save changes" link up in the right corner, but "delete this server". Without confirmation, we might add.
Saying all this, though, it is streets ahead of building your own server from scratch with CentOS or Debian. It's very easy to set up a file server, for instance, and it is a Primary Domain Controller by default, with a default home directory quota of 100MB applied. Oddly, we had to grant admin rights to one of the user accounts to add workstations to the domain – the system admin account could not do this.
Zentyal shows a huge amount of promise, but its relative immaturity shows. There are holes here and there where things either don't work or don't do what you might reasonably expect. Being charitable, Zentyal's occasional lack of integration could be interpreted as a less proprietary approach than SME Server or ClearOS, with their idiosyncratic multipurpose shares and so on. What's more, Zentyal is based on Ubuntu, and as that's the leading desktop distro, you're more likely to be familiar with it than the Red Hat family. While something CentOS-based would appeal more to those who know RHEL, this really means Linux professionals from big business – the exact sort of people who would not want a ready-rolled server but would prefer to build their own. Zentyal is also a lot more polished and integrated than the official Ubuntu Server, which is strictly for Linux experts or the seriously intrepid.
Right now, though, unless you're prepared to do some of the legwork yourself or are particularly wedded to Ubuntu, most people would be better off with SME Server or ClearOS. Find our in-depth reviews of SME Server here and our review of ClearOS here.