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NAME | SYNOPSIS | DESCRIPTION | EXAMPLE | SEE ALSO | COLOPHON |
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NSS-MYHOSTNAME(8) nss-myhostname NSS-MYHOSTNAME(8)
nss-myhostname, libnss_myhostname.so.2 - Provide hostname resolution
for the locally configured system hostname.
libnss_myhostname.so.2
nss-myhostname is a plug-in module for the GNU Name Service Switch
(NSS) functionality of the GNU C Library (glibc), primarily providing
hostname resolution for the locally configured system hostname as
returned by gethostname(2). The precise hostnames resolved by this
module are:
· The local, configured hostname is resolved to all locally
configured IP addresses ordered by their scope, or — if none are
configured — the IPv4 address 127.0.0.2 (which is on the local
loopback) and the IPv6 address ::1 (which is the local host).
· The hostnames "localhost" and "localhost.localdomain" (as well as
any hostname ending in ".localhost" or ".localhost.localdomain")
are resolved to the IP addresses 127.0.0.1 and ::1.
· The hostname "gateway" is resolved to all current default routing
gateway addresses, ordered by their metric. This assigns a stable
hostname to the current gateway, useful for referencing it
independently of the current network configuration state.
Various software relies on an always-resolvable local hostname. When
using dynamic hostnames, this is traditionally achieved by patching
/etc/hosts at the same time as changing the hostname. This is
problematic since it requires a writable /etc file system and is
fragile because the file might be edited by the administrator at the
same time. With nss-myhostname enabled, changing /etc/hosts is
unnecessary, and on many systems, the file becomes entirely optional.
To activate the NSS modules, add "myhostname" to the line starting
with "hosts:" in /etc/nsswitch.conf.
It is recommended to place "myhostname" last in the nsswitch.conf'
"hosts:" line to make sure that this mapping is only used as
fallback, and that any DNS or /etc/hosts based mapping takes
precedence.
Here is an example /etc/nsswitch.conf file that enables
nss-myhostname correctly:
passwd: compat mymachines systemd
group: compat mymachines systemd
shadow: compat
hosts: files mymachines resolve [!UNAVAIL=return] dns myhostname
networks: files
protocols: db files
services: db files
ethers: db files
rpc: db files
netgroup: nis
To test, use glibc's getent tool:
$ getent ahosts `hostname`
::1 STREAM omega
::1 DGRAM
::1 RAW
127.0.0.2 STREAM
127.0.0.2 DGRAM
127.0.0.2 RAW
In this case, the local hostname is omega.
systemd(1), nss-systemd(8), nss-resolve(8), nss-mymachines(8),
nsswitch.conf(5), getent(1)
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 2018-02-02. (At that
time, the date of the most recent commit that was found in the repos‐
itory was 2018-02-02.) 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 234 NSS-MYHOSTNAME(8)
Pages that refer to this page: systemd.directives(7), systemd.index(7), nss-mymachines(8), nss-resolve(8), nss-systemd(8)
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