NSS(5)                                                       Linux Programmer's Manual                                                      NSS(5)

NAME

       nss - Name Service Switch configuration file

DESCRIPTION

       Each  call  to  a  function  which retrieves data from a system database like the password or group database is handled by the Name Service
       Switch implementation in the GNU C library.  The various services provided are implemented by independent modules, each of which  naturally
       varies widely from the other.

       The  default  implementations  coming  with  the  GNU C library are by default conservative and do not use unsafe data.  This might be very
       costly in some situations, especially when the databases are large.  Some modules allow the system administrator to request  taking  short-
       cuts if these are known to be safe.  It is then the system administrator's responsibility to ensure the assumption is correct.

       There  are  other modules where the implementation changed over time.  If an implementation used to sacrifice speed for memory consumption,
       it might create problems if the preference is switched.

       The /etc/default/nss file contains a number of variable assignments.  Each variable controls the behavior  of  one  or  more  NSS  modules.
       White spaces are ignored.  Lines beginning with '#' are treated as comments.

       The variables currently recognized are:

       NETID_AUTHORITATIVE = TRUE|FALSE
              If set to TRUE, the NIS backend for the initgroups(3) function will accept the information from the netid.byname NIS map as authori-
              tative.  This can speed up the function significantly if the group.byname map is large.  The content of the netid.byname map is used
              as is.  The system administrator has to make sure it is correctly generated.

       SERVICES_AUTHORITATIVE = TRUE|FALSE
              If  set  to TRUE, the NIS backend for the getservbyname(3) and getservbyname_r(3) functions will assume that the services.byservice-
              name NIS map exists and is authoritative, particularly that it contains both keys with /proto and without /proto  for  both  primary
              service names and service aliases.  The system administrator has to make sure it is correctly generated.

       SETENT_BATCH_READ = TRUE|FALSE
              If  set  to  TRUE, the NIS backend for the setpwent(3) and setgrent(3) functions will read the entire database at once and then hand
              out the requests one by one from memory with every corresponding getpwent(3) or getgrent(3) call respectively.  Otherwise, each get-
              pwent(3) or getgrent(3) call might result in a network communication with the server to get the next entry.

FILES

       /etc/default/nss

EXAMPLE

       The default configuration corresponds to the following configuration file:

           NETID_AUTHORITATIVE=FALSE
           SERVICES_AUTHORITATIVE=FALSE
           SETENT_BATCH_READ=FALSE

SEE ALSO

       nsswitch.conf

COLOPHON

       This  page is part of release 4.15 of the Linux man-pages project.  A description of the project, information about reporting bugs, and the
       latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.

Linux                                                               2013-02-13                                                              NSS(5)