NSSCACHE.CONF(5)

💖 NSSCACHE.CONF(5) 💖

okay bestie, buckle UP — this is the manual page for nsscache.conf, and it's giving file formats energy in the best way possible 🎀

---

✨ NAME ✨

nsscache.conf — the NSS local cache synchroniser configuration file, aka the glow-up your name service lookups have been begging for 🦋

---

✨ SYNOPSIS ✨

/etc/nsscache.conf

that's it. that's the whole synopsis. iconic, honestly 💅

---

✨ DESCRIPTION ✨

So here's the vibe: nsscache synchronises a local NSS cache (and other databases too, it's multitasking like a queen 👑) against a remote data source. Why do we care? Because this approach lets the admin separate the network from the NSS lookup codepath, which improves both the speed and the reliability of name services. no more waiting on the network every single time you want to know who somebody is. periodt.

The nsscache configuration file is made of one DEFAULT section, followed by zero or more map-specific configuration sections. The file format is similar to that of .ini files, so if you've ever written one of those, you already know the shape of it.

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
• one timestamp_dir keyword — specifying the location of the timestamps used for incremental updates

Additional global defaults may also be included in the DEFAULT section — stuff like LDAP search parameters, or the filesystem location of the cache. go wild, it's your default zone 💖

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. see? flexible. main character behaviour. 💅

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

A complete list of configuration options follows. let's get into it, bestie 🌸

---

✨ DEFAULT-only OPTIONS ✨

These ones live in DEFAULT and DEFAULT only, no exceptions 💜

• 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. so many options, so much power 🧚

• 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) 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.

⚠️ bestie, pay attention to that one: nested group expansion only applies during a full sync, and if you set this, incremental synchronization should not be used. no cap.

• 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. cloud storage moment ☁️✨

• 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 : user10ser20ser3 }, 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. just grab it off the web, bestie 🌈

• 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. plain text, my beloved 🍓

• 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

look at that. a whole working config. you ate. 💅✨

---

and that's part one, bestie — more still to come, so don't go anywhere 🫶

✨ gcs SOURCE OPTIONS ✨

okay bestie so this is the gcs source block — it's where you tell nsscache how to vibe with Google Cloud Storage buckets 🫶 these options configure the behaviour of the gcs source, periodt.

• gcs_bucket — the Google Cloud Storage bucket holding your passwd, group, and shadow blobs. like, the whole lil home for your identity files 💖 and it comes with three sub-options, all of them nuzzled up under it:
  • gcs_passwd_object — the name of the object that contains passwd records in the standard format. for example:

root:*:0:0:System Administrator:/var/root:/bin/sh

• gcs_group_object — the name of the object that contains group records in the standard format. for example:

users:x:100:memberships....

• gcs_shadow_object — the name of the object containing shadow records in the standard format. for example:

root:*:18866:0:99999:7:::

---

📁 FILES 📁

• /etc/nsscache.conf — the system-wide nsscache configuration file. yes, the one. the main character config fr fr 👑

---

👀 SEE ALSO 👀

• nsscache(1) — the main event, the big sister page 🌟
• nsswitch.conf(5) — the system name service switch configuration file. it's giving gatekeeper energy but make it helpful 🎀
• ldap.conf(5) — all the details on LDAP configuration options exposed by the LDAP client libraries. iykyk 🧚

---

✍️ AUTHOR ✍️

Written by Jamie Wilkinson (jaq@google.com) and Vasilios Hoffman (vasilios@google.com). legends, honestly 💜

The source code lives at https://github.com/google/nsscache — go peek, it's lowkey iconic 🌈

---

©️ 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. like, zero warranty bestie, none, nada, not even the tiniest crumb 💀 read the fine print and respect it 🙈

---

and that's a wrap on NSSCACHE.CONF(5) 🎬 this lil beauty is from nsscache 0.49, dated 2023-06-03 — screenshot it, bookmark it, tattoo it on your forearm, whatever works for you. go forth and switch your name services with main character energy, bestie 💅✨🦋🌸