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[PATCH v3] nss: Make nsswitch.conf more distribution friendly.

This version incorporates all the feedback we've had so far, and
looks to be the most complete version we've ever had upstream.
I listed the autofs example that Andreas gave in the manual, since
it was relevant to point out to readers that the configuration actually
gets used by non-glibc system software.

v3 here for review.

8< --- 8< ---- 8<

The current default nsswitch.conf file provided by glibc is not very
distribution friendly. The file contains some minimal directives that no
real distribution uses. This update aims to provide a rich set of
comments which are useful for all distributions, and a broader set of
service defines which should work for all distributions.

Tested defaults on x86_64 and they work. The nsswitch.conf file more
closely matches what we have in Fedora now, and I'll adjust Fedora to
use this version with minor changes to enable Fedora-specific service

- Add missing databases to manual.
- Add link to manual from default nsswitch.conf.
- Sort nsswitch.conf according to most used database first.

- Only mention implemented services in 'NSS Basics.'
- Mention 'automount' in 'Services in the NSS configuration.'
- Sort services in alphabetical order.
 ChangeLog         |  6 ++++
 manual/nss.texi   | 24 +++++++++++---
 nss/nsswitch.conf | 81 +++++++++++++++++++++++++++++++++++++----------
 3 files changed, 90 insertions(+), 21 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 82e03e8d05..270b87f7d8 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2019-03-25  Carlos O'Donell  <>
+	* nss/nsswitch.conf: Expand comments, and simplify defaults.
+	* manual/nss.texi (NSS Basics): List all known databases.
+	(Services in the NSS configuration): Mention automount.
 2019-03-25  Adhemerval Zanella  <>
* sysdeps/powerpc/fpu/s_float_bitwise.h: Remove file.
diff --git a/manual/nss.texi b/manual/nss.texi
index 164ae33246..2d5aecd487 100644
--- a/manual/nss.texi
+++ b/manual/nss.texi
@@ -56,13 +56,17 @@ functions to access the databases.
 The databases available in the NSS are
+@cindex aliases
 @cindex ethers
 @cindex group
+@cindex gshadow
 @cindex hosts
+@cindex initgroups
 @cindex netgroup
 @cindex networks
-@cindex protocols
 @cindex passwd
+@cindex protocols
+@cindex publickey
 @cindex rpc
 @cindex services
 @cindex shadow
@@ -75,16 +79,22 @@ Ethernet numbers,
 @comment @pxref{Ethernet Numbers}.
 @item group
 Groups of users, @pxref{Group Database}.
+@item gshadow
+Group passphrase hashes and related information.
 @item hosts
 Host names and numbers, @pxref{Host Names}.
+@item initgroups
+Supplementary group access list.
 @item netgroup
 Network wide list of host and users, @pxref{Netgroup Database}.
 @item networks
 Network names and numbers, @pxref{Networks Database}.
-@item protocols
-Network protocols, @pxref{Protocols Database}.
 @item passwd
 User identities, @pxref{User Database}.
+@item protocols
+Network protocols, @pxref{Protocols Database}.
+@item publickey
+Public keys for Secure RPC.
 @item rpc
 Remote procedure call names and numbers.
 @comment @pxref{RPC Database}.
@@ -96,8 +106,8 @@ User passphrase hashes and related information.
 @end table
-There will be some more added later (@code{automount}, @code{bootparams},
-@code{netmasks}, and @code{publickey}).
+@c We currently don't implement automount, netmasks, or bootparams.
+More databasess may be added later.
@node NSS Configuration File, NSS Module Internals, NSS Basics, Name Service Switch
 @section The NSS Configuration File
@@ -159,6 +169,10 @@ these files since they should be placed in a directory where they are
 found automatically.  Only the names of all available services are
+Lastly, some system software may make use of the NSS configuration file
+to store it's own configuration for similar purposes.  Examples of this
+include the @code{automount} service which is used by @code{autofs}.
 @node Actions in the NSS configuration, Notes on NSS Configuration File, Services in the NSS configuration, NSS Configuration File
 @subsection Actions in the NSS configuration
diff --git a/nss/nsswitch.conf b/nss/nsswitch.conf
index 39ca88bf51..4919201483 100644
--- a/nss/nsswitch.conf
+++ b/nss/nsswitch.conf
@@ -1,20 +1,69 @@
 # /etc/nsswitch.conf
-# Example configuration of GNU Name Service Switch functionality.
+# An example Name Service Switch config file. This file should be
+# sorted with the most-used services at the beginning.
+# Valid databases are: aliases, ethers, group, gshadow, hosts,
+# initgroups, netgroup, networks, passwd, protocols, publickey,
+# rpc, services, and shadow.
+# Valid service provider entries include (in alphabetical order):
+#	compat			Use /etc files plus *_compat pseudo-db
+#	db			Use the pre-processed /var/db files
+#	dns			Use DNS (Domain Name Service)
+#	files			Use the local files in /etc
+#	hesiod			Use Hesiod (DNS) for user lookups
+#	nis			Use NIS (NIS version 2), also called YP
+#	nisplus			Use NIS+ (NIS version 3)
+# See `info libc 'NSS Basics'` for more information.
+# Commonly used alternative service providers (may need installation):
+#	ldap			Use LDAP directory server
+#	myhostname		Use systemd host names
+#	mymachines		Use systemd machine names
+#	mdns*, mdns*_minimal	Use Avahi mDNS/DNS-SD
+#	resolve			Use systemd resolved resolver
+#	sss			Use System Security Services Daemon (sssd)
+#	systemd			Use systemd for dynamic user option
+#	winbind			Use SAMBA winbind support
+#	wins			Use SAMBA wins support
+#	wrapper			Use wrapper module for testing
+# Notes:
+# 'sssd' performs its own 'files'-based caching, so it should generally
+# come before 'files'.
+# WARNING: Running nscd with a secondary caching service like sssd may
+# 	   lead to unexpected behaviour, especially with how long
+# 	   entries are cached.
+# Installation instructions:
+# To use 'db', install the appropriate package(s) (provide 'makedb' and
+#*), and place the 'db' in front of 'files' for entries
+# you want to be looked up first in the databases, like this:
+# passwd:    db files
+# shadow:    db files
+# group:     db files
-passwd: db files
-group:		db files
-initgroups:	db [SUCCESS=continue] files
-shadow:		db files
-gshadow:	files
-hosts:		files dns
-networks:	files dns
-protocols:	db files
-services:	db files
-ethers:		db files
-rpc:		db files
-netgroup:	db files
+# In alphabetical order. Re-order as required to optimize peformance.
+aliases:    files
+ethers:     files
+group:      files
+gshadow:    files
+hosts:      files dns
+initgroups: files
+netgroup:   files
+networks:   files dns
+passwd:     files
+protocols:  files
+publickey:  files
+rpc:        files
+shadow:     files
+services:   files


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