OpenBSD Gets Harder to Crack

Version 3.3's attack defenses are even stronger.

OpenBSD 3.3

Organizations deploying firewalls or virtual private networks—and preferring to do so on servers rather than dedicated appliances—should consider the highly secure and easy-to-configure OpenBSD. The operating systems security track record embarrasses all others, and this release continues to advance the state of the art in attack defense. The product is free to download, or a CD set can be ordered for $40.
















  • PRO: Unmatched security track record; secure-out-of-the-box deployment; packet filter provides complete traffic filtering features, along with traffic shaping and load balancing; the latest in buffer overflow prevention technology with ProPolice and page-level memory permissions.
  • CON: Update mechanisms are labor-intensive for system administrators; memory protection features not currently available on x86 CPUs; no mandatory access control features to limit the power of root-level exploits; not well-supported by commercial server software vendors.

• Security-oriented Linux distributions • Hardware appliances • Trusted OS add-ons

On the security field, nothing is quite as revealing—or as taxing—as the passage of time.

By that measure in particular, the OpenBSD development teams OpenBSD operating system stands out. The latest OpenBSD 3.3 release, which started shipping early last month, arrives with even stronger attack defenses coupled with an amazing record of just a single remotely exploitable vulnerability in more than seven years, the best security track record for any general-purpose operating system around.

eWEEK Labs has used past versions of OpenBSD for a number of years in our lab for network firewalls as well as in OpenHack security tests and have come to trust the products rock-solid reliability and secure-out-of-the-box configuration. Its free to download or $40 for a CD version.

This release improves the packages already-powerful network filtering features with the addition of bandwidth preallocation, selective traffic prioritization and load balancing.

For network firewall or router deployments, OpenBSD provides a secure, easy-to-configure option, while still supporting the deployment of general-purpose network server applications such as The Apache Software Foundations HTTP Server or Internet Software Consortiums BIND (Berkeley Internet Name Domain) name server. (Apache 1.3.27 and BIND 9.2.2 are installed on OpenBSD 3.3 by default.)

Although OpenBSD has a generous set of prebuilt software packages available for it (installing KDE, or K Desktop Environment, 3.1 was very straightforward), it is not well-supported by commercial server software vendors the way Linux, Windows or Solaris is. It also doesnt support more than one CPU per server.

Keeping an OpenBSD system up-to-date is also very demanding for system administrators. Configuration files in /etc need to be manually migrated during version upgrades (which ship every six months), and security patches are released only in source code form. A binary patch distribution tool would make it much easier to deploy OpenBSD systems in larger numbers.

Overflow Attack Protection

OpenBSD 3.3 enables by default ProPolice, an application buffer overflow protection mechanism developed by IBM Research. To get this protection, users need to compile applications with the ProPolice-equipped GNU Compiler Collection compiler that comes with OpenBSD or use just the already-protected applications that ship with OpenBSD.

OpenBSD 3.3 adds page-level memory permissions (on SPARC, Alpha and PA-RISC CPUs) that mark each memory page as either writable or executable (but not both at once), to make it harder for an attacker to write attack code into a memory location and execute it.

Unfortunately, this feature isnt provided on x86 or PowerPC chips yet, although its planned for the OpenBSD 3.4 release.

The OpenBSD project has made a decision against trusted-operating-system-style mandatory access controls that place kernel-enforced limits on what particular processes or users can do. "People who use such things build systems which cannot be administered later," said Theo de Raadt, OpenBSD project leader, in Calgary, Alberta. "I am holding the fort against such complexity."

However, while mandatory access controls do make systems harder to administer, weve found the approach a very powerful defense in tests and would welcome the option to use these techniques with OpenBSD.

OpenBSDs excellent packet filter, pf, is a big attraction of the platform because it provides such comprehensive firewall features coupled with a concise yet simple configuration file format.

This release updates pf with traffic-shaping features that let administrators devote a set amount of bandwidth or a relative percentage of bandwidth to particular types of traffic or particular users. It also lets administrators prioritize selected types of traffic.

West Coast Technical Director Timothy Dyck is at