This article is from the Frequently Asked Questions for Linux, the Free/Open Source UNIX-like operating system kernel that runs on many modern computer systems. Maintained by David C. Merrill with numerous contributions by others. (v1.0).
A: You are probably using non-shadow password programs and are using shadow passwords.
If so, you have to get or compile a shadow password version of the programs in question. The shadow password suite can be found at ftp://tsx-11.mit.edu/ pub/linux/sources/usr.bin/shadow/. This is the source code. The binaries are probably in linux/binaries/usr.bin/.