Maintaining Patch Levels with Open Source BSDs

Michael Lucas

The open source BSDs are based on 20-year-old UNIX code released by the University of California Berkeley in the early 1990s. Today, open source BSD has broken into three branches: FreeBSD, NetBSD, and OpenBSD. Each has its own focus. NetBSD runs on almost any hardware. OpenBSD's focus is security on a wide hardware base. FreeBSD focuses on being the most stable, high-performance OS possible on Intel CPUs. Versions of the open source BSDs are used on several major ISP Web sites and in many commercial organizations. Besides time-tested code and top-notch performance, however, all the BSDs offer three main features.

The emulation functions are an important feature. Most open source BSDs can run binaries for SVR4, SCO UNIX, BSDI, character-mode DOS, and Linux. The Linux emulation alone is remarkable; applications from WordPerfect to Informix run perfectly. The second advantage (for corporate users, at least) is the license. The BSD license boils down to: "Give us credit for our work, and don't sue us if something breaks." There is no obligation to make changes public or to propagate source code. The last advantage is the very easy upgrade method. This article was written on a FreeBSD machine, installed in November of 1997. It's running a version of FreeBSD less than a week old. I upgrade the operating system every week, and it takes less than fifteen minutes each time. This is due to the BSD development model and tools like sup and CVSup.

This article focuses on upgrading FreeBSD systems, but the concepts are applicable in both OpenBSD and NetBSD. Some of the procedures are slightly different, but pointers to detailed information for each BSD are provided.<>