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
· 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
Here is an example /etc/nsswitch.conf file that enables
passwd: compat mymachines
group: compat mymachines
hosts: files mymachines resolve myhostname
protocols: db files
services: db files
ethers: db files
rpc: db files
To test, use glibc's getent tool:
$ getent ahosts `hostname`
::1 STREAM omega
In this case, the local hostname is omega.
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systemd 230 NSS-MYHOSTNAME(8)