nss-myhostname, libnss_myhostname.so.2 — Provide hostname resolution for the locally configured system hostname.
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.localdomain" (as well as any hostname
ending in "
.localhost" or "
are resolved to the IP addresses 127.0.0.1 and ::1.
The hostname "
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,
/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
It is recommended to place "
myhostname" last in the
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
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