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NAME | SYNOPSIS | DESCRIPTION | CONFIGURATION IN /ETC/NSSWITCH.CONF | EXAMPLE: MAPPINGS PROVIDED BY SYSTEMD-MACHINED.SERVICE | SEE ALSO | NOTES | COLOPHON |
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NSS-SYSTEMD(8) nss-systemd NSS-SYSTEMD(8)
nss-systemd, libnss_systemd.so.2 - UNIX user and group name
resolution for user/group lookup via Varlink
libnss_systemd.so.2
nss-systemd is a plug-in module for the GNU Name Service Switch
(NSS) functionality of the GNU C Library (glibc), providing UNIX
user and group name resolution for services implementing the
User/Group Record Lookup API via Varlink[1], such as the system
and service manager systemd(1) (for its DynamicUser= feature, see
systemd.exec(5) for details), systemd-homed.service(8), or
systemd-machined.service(8).
This module also ensures that the root and nobody users and
groups (i.e. the users/groups with the UIDs/GIDs 0 and 65534)
remain resolvable at all times, even if they aren't listed in
/etc/passwd or /etc/group, or if these files are missing.
This module preferably utilizes systemd-userdbd.service(8) for
resolving users and groups, but also works without the service
running.
To activate the NSS module, add "systemd" to the lines starting
with "passwd:" and "group:" in /etc/nsswitch.conf.
It is recommended to place "systemd" after the "files" or
"compat" entry of the /etc/nsswitch.conf lines so that
/etc/passwd and /etc/group based mappings take precedence.
Here is an example /etc/nsswitch.conf file that enables
nss-systemd correctly:
passwd: compat systemd
group: compat [SUCCESS=merge] systemd
shadow: compat
hosts: mymachines resolve [!UNAVAIL=return] files myhostname dns
networks: files
protocols: db files
services: db files
ethers: db files
rpc: db files
netgroup: nis
The container "rawhide" is spawned using systemd-nspawn(1):
# systemd-nspawn -M rawhide --boot --network-veth --private-users=pick
Spawning container rawhide on /var/lib/machines/rawhide.
Selected user namespace base 20119552 and range 65536.
...
$ machinectl --max-addresses=3
MACHINE CLASS SERVICE OS VERSION ADDRESSES
rawhide container systemd-nspawn fedora 30 169.254.40.164 fe80::94aa:3aff:fe7b:d4b9
$ getent passwd vu-rawhide-0 vu-rawhide-81
vu-rawhide-0:*:20119552:65534:vu-rawhide-0:/:/usr/sbin/nologin
vu-rawhide-81:*:20119633:65534:vu-rawhide-81:/:/usr/sbin/nologin
$ getent group vg-rawhide-0 vg-rawhide-81
vg-rawhide-0:*:20119552:
vg-rawhide-81:*:20119633:
$ ps -o user:15,pid,tty,command -e|grep '^vu-rawhide'
vu-rawhide-0 692 ? /usr/lib/systemd/systemd
vu-rawhide-0 731 ? /usr/lib/systemd/systemd-journald
vu-rawhide-192 734 ? /usr/lib/systemd/systemd-networkd
vu-rawhide-193 738 ? /usr/lib/systemd/systemd-resolved
vu-rawhide-0 742 ? /usr/lib/systemd/systemd-logind
vu-rawhide-81 744 ? /usr/bin/dbus-daemon --system --address=systemd: --nofork --nopidfile --systemd-activation --syslog-only
vu-rawhide-0 746 ? /usr/sbin/sshd -D ...
vu-rawhide-0 752 ? /usr/lib/systemd/systemd --user
vu-rawhide-0 753 ? (sd-pam)
vu-rawhide-0 1628 ? login -- zbyszek
vu-rawhide-1000 1630 ? /usr/lib/systemd/systemd --user
vu-rawhide-1000 1631 ? (sd-pam)
vu-rawhide-1000 1637 pts/8 -zsh
systemd(1), systemd.exec(5), nss-resolve(8), nss-myhostname(8),
nss-mymachines(8), systemd-userdbd.service(8),
systemd-homed.service(8), systemd-machined.service(8),
nsswitch.conf(5), getent(1)
1. User/Group Record Lookup API via Varlink
https://systemd.io/USER_GROUP_API
This page is part of the systemd (systemd system and service
manager) project. Information about the project can be found at
⟨http://www.freedesktop.org/wiki/Software/systemd⟩. If you have
a bug report for this manual page, see
⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.
This page was obtained from the project's upstream Git repository
⟨https://github.com/systemd/systemd.git⟩ on 2020-12-18. (At that
time, the date of the most recent commit that was found in the
repository was 2020-12-18.) If you discover any rendering
problems in this HTML version of the page, or you believe there
is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
systemd 247 NSS-SYSTEMD(8)
Pages that refer to this page: userdbctl(1), systemd.exec(5), systemd.directives(7), systemd.index(7), nss-myhostname(8), nss-mymachines(8), nss-resolve(8), systemd-userdbd.service(8)
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HTML rendering created 2020-12-21 by Michael Kerrisk, author of The Linux Programming Interface, maintainer of the Linux man-pages project. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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