---
name: "nsscache.conf"
section: "5"
platform: "linux"
package: "nsscache"
version: "0.49-5"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/nsscache.conf"
---

# nsscache.conf(5)

NSS local cache synchroniser configuration file

## NAME

nsscache.conf - NSS local cache synchroniser configuration file

## SYNOPSIS

**/etc/nsscache.conf**

## DESCRIPTION

**nsscache** synchronises a local NSS cache, and other databases, against a remote data source. This approach allows the administrator to separate the network from the NSS lookup codepath, improving speed and reliability of name services.

The nsscache configuration file comprises of one DEFAULT section, followed by zero or more map-specific configuration sections.  The file format is similar to that of ".ini" files.

The DEFAULT section must provide at least one **source** keyword, specifying the data source to use, one **cache** keyword, specifying the means in which the cache data will be stored locally, one **maps** keyword, specifying which NSS maps should be cached, and one **timestamp\_dir** keyword, specifying the location of the timestamps used for incremental updates.

Additional global defaults, such as LDAP search parameters, or the filesystem location of the cache, may also be included in the DEFAULT section.

Additional sections may be included that allow per-map overrides to configuration options.  For example, one might specify their global LDAP search base as **ou=People** but want to override that for the *group* mapping as **ou=Groups**

Apart from the *source*, *cache*, and *maps* configuration options, all options are prefixed by the name of the module that they configure.

A complete list of configuration options follows.

## DEFAULT-only OPTIONS

- **source**

  Specifies the source to use to retrieve NSS data from.

  Valid Options: *ldap, s3, http, gcs*

- **cache**

  Specifies the cache method to use to store the data, which will be queried by the NSS itself.

  Valid options: *files* Store in a plain text file, similar in format to */etc/passwd.* If the files-module option *files\_cache\_filename\_suffix* is also set to **cache** then not only will the files be created with a **.cache** suffix, but also an index file will be written alongside, for use with the *nss-cache* NSS module.  (See https://github.com/google/libnss-cache.)

- **maps**

  Specifies the names of the maps that will be queried and cached by *nsscache*

  Valid options: *passwd* *group* *shadow* *netgroup* *automount* *sshkey*

- **timestamp\_dir**

  Specifies the directory where update and modify timestamps are stored.

## ldap SOURCE OPTIONS

These options configure the behaviour of the *ldap* source.

- **ldap\_ad**

  Set to 1 if connecting to Active Directory. If enabled, default Active Directory attributes will be used for mapping. Leave disabled if connecting to *openldap.*

- **ldap\_uri**

  The LDAP URI to connect to.

- **ldap\_base**

  The base to perform LDAP searches under.

- **ldap\_filter**

  The search filter to use when querying.

- **ldap\_scope**

  The search scope to use.  Defaults to *one*

  Valid options: *sub\[tree\]* *one\[level\]* *base*

- **ldap\_bind\_dn**

  The bind DN to use when connecting to LDAP.  Empty string is an anonymous bind.  Defaults to the empty string.

- **ldap\_bind\_password**

  The bind password to use when connecting to LDAP.  Empty string is used for anonymous binds.  Defaults to the empty string.

- **ldap\_timelimit**

  Timelimit in seconds for search results to return.  -1 means no limit. Defaults to -1.

- **ldap\_retry\_max**

  Number of retries on soft failures before giving up.  Defaults to 3.

- **ldap\_retry\_delay**

  Delay in seconds between retries.  Defaults to 5.

- **ldap\_tls\_require\_cert**

  Sets expectations for SSL certificates, using TLS.  One of 'never', 'hard', 'demand', 'allow', or 'try' ('demand' is the default).  See [**ldap.conf**(5)](/ldap.conf/5.md) for more information.

- **ldap\_tls\_cacertdir**

  Directory for trusted CA certificates.  By default, the system's default CA certificate directory will be used.

- **ldap\_tls\_cacertfile**

  Filename containing trusted CA certificates.

- **ldap\_tls\_certfile**

  Filename of an optional LDAP client certificate. If specified, **ldap\_tls\_keyfile** must also be specified.

- **ldap\_tls\_keyfile**

  Filename of an optional LDAP client key.  Only plaintext (unencrypted) keys are currently supported.  If specified, **ldap\_tls\_certfile** must also be specified.

- **ldap\_tls\_starttls**

  Set to 1 to enable STARTTLS. Leave absent to disable.

- **ldap\_uidattr**

  The uid-like attribute in your directory. Defaults to uid.

- **ldap\_use\_rid**

  If enabled (set to 1) the relative identifier (RID) wll be used for mapping. By default **uidNumber** and **gidNumber** will be mapped when connecting to OpenLDAP with a POSIX-like schema. When using Samba4 AD, these attributes won't exist. Leave disabled for default. It has no effect if the option **ldap\_ad** is enabled.

- **ldap\_offset**

  Default Offset option to map uidNumber and gidNumber to higher number. This can be useful to avoid conflict with already existing uidNumber and gidNumber.

- **ldap\_uidregex**

  A Python regex to extract uid components from the uid-like attribute. All matching groups are concatenated without spaces. For example:  '(.\*)@example.com' would return a uid to the left of the @example.com domain.  Default is no regex.

- **ldap\_groupregex**

  A Python regex to extract group member components from the member or memberOf attributes.  All matching groups are concatenated without spaces. For example:  '(.\*)@example.com' would return a member without the the @example.com domain.  Default is no regex.

- **ldap\_nested\_groups**

  To enable expansion of nested groups, set this to 1. Note that this only applies during a full sync, and incremental synchronization should not be used if this is set.

- **ldap\_override\_shell**

  If specified, set every user's login shell to the given one. May be useful on bastion hosts or to ensure uniformity. Enable for Active Directory since the attribute (loginShell) is not default.

- **ldap\_home\_dir**

  Set a home directory for all users in passwd. If enabled (set to 1), all users will have their home directory in */home.*

- **ldap\_rfc2307bis**

  Default uses rfc2307 schema. If rfc2307bis (groups stored as a list of DNs in 'member' attr), set this to 1.

- **ldap\_debug**

  Sets the debug level for the underlying C library.  Defaults to no logging.

## s3 SOURCE OPTIONS

These options configure the behaviour of the *s3* source.

- **s3\_bucket**

  AWS S3 bucket containing *passwd, group, shadow* objects. **boto3** python package should be installed to use this type of source. It is highly recommended to use s3 source only with AWS IAM role attached to the ec2 instance configured for read-only access to the bucket. So no extra configuration options like access\_key and secret provided in config. Though they may be used via ~/.aws/config and ~/.aws/credentials because python boto3 library used in implementation is capable to read them by itself.

- **s3\_passwd\_object**

  Object containing **passwd** array of records in json format. E.g. *\[{"Value": {"gid": 10000, uid : 10000}, Key : user1 }\].* Valid attributes: *comment , home , shell , passwd , gid , uid*

- **s3\_group\_object**

  Object containing **group** array of records in json format. E.g. *\[{"Value": {"gid": 20000, members : user1\\nuser2\\nuser3 }, Key : group1 }\].* Valid attributes: *gid , members* Members should be sequence of usernames split by \\n (see example above)

- **s3\_shadow\_object**

  Object containing **shadow** array of records in json format. E.g. *\[{"Value": {"passwd": \* }, Key : user1 }\].* Valid attributes: *passwd , lstchg , min , max , warn , inact , expire*

- **s3\_sshkey\_object**

  Object containing **sshkey** array of records in json format. E.g. *\[{"Value": {"sshPublicKey": ssh-rsa ... }, Key : user1 }\].* Valid attributes: *sshPublicKey*

## http SOURCE OPTIONS

These options configure the behaviour of the *http* source.

- **http\_passwd\_url**

  URL for an HTTP endpoint that returns a file containing **passwd** records in the standard format. E.g. *root:\*:0:0:System Administrator:/var/root:/bin/sh*

- **http\_group\_url**

  URL for an HTTP endpoint that returns a file containing **group** records in the standard format. E.g. *users:x:100:memberships....*

- **http\_shadow\_url**

  URL for an HTTP endpoint that returns a file containing **shadow** records in the standard format. E.g. *root:\*:18866:0:99999:7:::*

- **http\_sshkey\_url**

  URL for an HTTP endpoint that returns a file containing **sshkey** records in the standard format. E.g. *root:ssh-rsa ...*

## files CACHE OPTIONS

These options configure the behaviour of the *files* cache.

- **files\_dir**

  Directory location to store the plain text files in.  Defaults to the current directory.

- **files\_cache\_filename\_suffix**

  A suffix appended to the cache filename to differentiate it from, say, system NSS databases.  Defaults to '.cache'.

- **files\_local\_automount\_master**

  A yes/no field only used for automount maps.  A 'yes' value will cause nsscache to update the auto.master file with the master map from the source.  A 'no' value will cause nsscache to leave auto.master alone, allowing the system to manage this file in other ways.  When set to 'no', nsscache will only update other automount maps defined both locally and in the source.  Defaults to 'yes'.

- **prefix**

  A regular expression to capture a prefix, or mount point.

- **suffix**

  A regular expression to modify the prefix.

## EXAMPLE

A typical example might look like this:

  \[DEFAULT\]\
   source = ldap\
   cache = files\
   maps = passwd, group, shadow\
   ldap\_uri = ldap://ldap.example.com\
   ldap\_base = ou=People,dc=example,dc=com\
   ldap\_filter = (objectclass=posixAccount)

  files\_dir = /etc\
   files\_cache\_filename\_suffix = cache

  \[group\]\
   ldap\_base = ou=Group,dc=example,dc=com\
   ldap\_filter = (objectclass=posixGroup)\
   ldap\_nested\_groups = 1

  \[shadow\]\
   ldap\_filter = (objectclass=posixAccount)

And a complementary */etc/nsswitch.conf* might look like this:

  passwd: files cache\
   group: files cache\
   shadow: files cache

## gcs SOURCE OPTIONS

These options configure the behaviour of the *gcs* source.

- **gcs\_bucket**

  Google Cloud Storage bucket containing *passwd, group, shadow* blobs.

  **gcs\_passwd\_object** Name for a object containing **passwd** records in the standard format. E.g. *root:\*:0:0:System Administrator:/var/root:/bin/sh*

  **gcs\_group\_object** Name for a object containing **group** records in the standard format E.g. *users:x:100:memberships....*

  **gcs\_shadow\_object** Name of the object containing **shadow** records in the standard format. E.g. *root:\*:18866:0:99999:7:::*

## FILES

- */etc/nsscache.conf*

  The system-wide nsscache configuration file

## SEE ALSO

- [*nsscache*(1)](/nsscache/1.md)

  - [*nsswitch.conf*(5)](/nsswitch.conf/5.md)

  The system name service switch configuration file

- [*ldap.conf*(5)](/ldap.conf/5.md)

  Details on LDAP configuration options exposed by the LDAP client libraries.

## AUTHOR

Written by Jamie Wilkinson (jaq@google.com) and Vasilios Hoffman (vasilios@google.com).

- The source code lives at https://github.com/google/nsscache

  ## COPYRIGHT

Copyright © 2007 Google, Inc.\
 This is free software; see the source for copying conditions.  There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.