NSS-MYHOSTNAME(8)nss-myhostnameNSS-MYHOSTNAME(8)NAME
nss-myhostname, libnss_myhostname.so.2 - Provide hostname resolution
for the locally configured system hostname.
SYNOPSIS
libnss_myhostname.so.2
DESCRIPTIONnss-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.
EXAMPLE
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.
SEE ALSOsystemd(1), nss-systemd(8), nss-resolve(8), nss-mymachines(8),
nsswitch.conf(5), getent(1)systemd 236NSS-MYHOSTNAME(8)
