1.1.5 and later
The PersistentPasswd directive controls how proftpd handles authentication, user/group lookups, and user/group to name mapping. If set to "on", proftpd will attempt to open the system-wide /etc/passwd, /etc/group (and /etc/shadow, potentially) files itself, holding them open even during a chroot()ed login. Note that /etc/shadow is never held open, for security reasons). On some platforms, you must turn this option on, as the libc functions are incapable of accessing these databases from inside of a chroot(). At configure-time, the configuration script will attempt to detect whether or not you need this support, and make it the default. However, such "guessing" may fail, and you will have to manually enable or disable the feature. If you cannot see user or group names when performing a directory listing inside an anonymous chrooted login, this indicates you must enable the directive. Use of the AuthUserFile or AuthGroupFile directives will force partial support for persistent user or group database files, regardless of PersistentPasswd's setting.
Note: NIS/NIS+ and NSS users will most likely want to disable this feature, regardless of proftpd's detected configuration defaults. Failure to disable this will make your NIS/NIS+ maps and NSS lookups not work! On certain systems, you may also need to compile ProFTPD with the --enable-autoshadow option in order to authenticate both users from NIS maps or NSS lookups, and local users.