Ubuntu Server: Lean, mean, cloud-making machine

Ubuntu Server is a fast, free, no-frills Linux distribution that fills a niche between utilitarian Debian and the GUI-driven and, some would argue, over-featured Novell SUSE and Red Hat Enterprise Linux.

In our business transactions benchmarking tests, Canonical's Ubuntu Server 9.0.4 was nearly as fast as the closest Linux cousin we've reviewed recently, Novell's SUSE Linux Enterprise Server 11.

Ubuntu Server doesn't have a GUI. Instead, at installation, users have the choice of adding services, such as DNS, LAMP (Linux Apache MySQL PHP), mail, OpenSSH, PostgreSQL database, print services, SAMBA and/or TomCat Java services.

Users can also configure the server as a svelte virtual machine or manually install server applications and utilities. The installation choices are offered through a simple 'VGA' (character) graphics menu.

Ubuntu Server also includes a version of Eucalyptus -- an open source tool for implementing Linux on public and private clouds. It's compatible with Amazon's Elastic Compute Cloud (EC2), Simple Storage Service (S3) and Elastic Book Store (EBS).

Eucalyptus, based on an open source project at the University of California at Santa Barbara, is comprised of a cloud controller, a cluster controller and node controller. Together, various nodes (operating instances where the work actually happens) are tied together either in local or disparate server locations, according to the desired computational strength, and the needs of availability of the nodes to do actual work.

Since communication among the components uses SOAP, a commonly understood mechanism in application development, we found building clusters into our own cloud to be pretty simple.

OEM opportunities

These selections map to popular uses of Linux servers, and an 'OEM' installation can also be made that makes a distributable 'cut' of Ubuntu server for pre-installed application server deployments.

The OEM 'cut' can 'ask questions' of end-user installers in order to configure or setup the server via a text-based interface. Before this version, only UbuntuDesktop could use the OEM tools, as they were GUI only.

These considerations and options are reminiscent of far older VAR (value added redistributor/developer-sourced) versions of Xenix, UnixWare, and other i386/486 versions of Unix, and hints at the potential for this totally zero-cost Linux distribution.

In fact, the only thing you can buy is extended support, as the first 18 months of support are free. If 'free' wasn't enough, it's also possible to strip out (at installation) any installation of 'non-free' (closed source or non-GPL/Apache-licensed) software, which will make free open source software (F/OSS) purists tingle.

Ubuntu 9.0.4 is a headless server operating system that's best downloaded from one of many mirror sites and is delivered in the form of an ISO image. From there, it can be burned to media or installed by various virtual machine hypervisor installer applications. We tried both methods successfully.

At installation, the default file system used is ext3, which can be simply changed to ext4, ReiserFS, or even NTFS. A script guides installation, and defaults will install only minimal components, which we like.

However, when we wanted to make changes, we found some of the choices cryptic. Fortunately, each option permits IT managers to 'go back,' although contextual help is unavailable.

Instead, we looked up selections in Ubuntu's documentation, which is reasonable for non-civilian installers and comes either from online sources or a fat, downloadable PDF file.

There are two different mail/message transfer systems that can be installed (initially or later), industry stalwart postfix or exim4 . The Ubuntu Server distribution includes Dovecot, which delivers POP3 or IMAP4 mail. Delivery of mail to users and list management is performed by the GNU mailman application, which is based on Python and works with either postfix of exim4.

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Wikis are offered through the moin moin (mine mine) application, which is also Python (and Apache2)-based. Ubuntu Server also ships with OpenLDAP as a directory services source, as well as Windows-connecting SAMBA 3.3. There's also connectivity via the OpenChange library to Microsoft's Exchange Server (for versions prior to Exchange 2007), although we didn't test this.

We found some of the installation options interesting. The administrator home directory can be optionally encrypted. More interesting was the fact that the commands in the traditional /etc directory can be subject to versioning control, which ensures that contents placed there (usually utility commands and configuration files) can be rolled back, or examined for tampering.

The /etc directory uses the etckeeper package that connects to the Advanced Package Tool (apt), the Debian Linux command that manages packages, as in application dependencies and component relationships. Etckeeper automatically notes changes when a new package is installed or updated. You can also commit changes if you edit a file manually in /etc.

Ubuntu Server is no slouch, compared with other Linux server editions that use the same kernel (2.6.28). Using Java 1.6, the SPECjbb2005 result for Ubuntu 9.04 server (averaged more than three runs) was 42,288.67 bops compared with 42,581.5 bops for SLES 11 in our recent review. The SPECjbb2005 test largely tracks business transactions and exercises CPU and memory rather than disk and network I/O.

What we didn't like

Out of habit, we use strong passwords, but Ubuntu doesn't by default enforce them. We found it ironic that we could encrypt user 'home' directories, but their passwords could be junk.

Ubuntu Server does support the trend of not allowing a superuser/root to be run by default -- meaning that root user tasks must be run by the sudo ('superuser do') root privilege command or a shell launched from it.

Ubuntu Server also features ufw, (the uncomplicated firewall) which can be controlled by the debianconf tool (not included but easily downloaded), and an OEM configuration can be 'pre-seeded' with allowed and rejected ports if desired. However, more complicated rules (example: acceptance from specific IP ranges or host table sourcing for access rules) don't work until after installation. The upside is that ufw can use Linux iptables for its iptables reject (turn network traffic off to start), but this isn't the default.

Additional authentication methods are available, but Ubuntu doesn't really give much information about how to enable them; it's up to the skills of the installer to make biometric, or proxy authentication methods work. If you want a certificate authority and something like AES encryption with temporal keys, you have to install it yourself, unlike Ubuntu's larger cousins.

Back to the future

Ubuntu Server reminds us of the Xenix, UnixWare, and even early SunOS and Solaris version that were targeted toward VARs and vertical market 'solutions' platforms. There are a lot of choices that arrive in the Ubuntu distribution, and it's based on Debian, which is known to be less experimental than other Linux distributions.

It's fast, utilitarian, and among the first Linux distros to link to clouds and clusters using standard components. Ubuntu Server's not so much lightweight, as just a little loose and fast in places.

Henderson and Allen are researchers for ExtremeLabs. They can be reached at kitchen-sink@extremelabs.com.