OpenBSD security features

The OpenBSD operating system is noted for its focus on security and for the development of a number of security features.

Bugs and security flaws are often caused by programmer error. A common source of error is the misuse of the strcpy and strcat string functions in the C programming language. There are two common alternatives, strncpy and strncat, but they can be difficult to understand and easy to misuse, so OpenBSD developers Todd C. Miller and Theo de Raadt designed the strlcpy and strlcat functions. These functions are intended to make it harder for programmers to accidentally leave buffers unterminated or allow them to be overflowed. They have been adopted by the NetBSD and FreeBSD projects but not by the GNU C Library.

On OpenBSD, the linker has been changed to issue a warning when unsafe string manipulation functions, such as strcpy, strcat, or sprintf, are found. All occurrences of these functions in the OpenBSD source tree have been replaced. In addition, a static bounds checker is included in OpenBSD in an attempt to find other common programming mistakes at compile time. Other security-related APIs developed by the OpenBSD project include issetugid and arc4random.

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