nss-myhostname, libnss_myhostname.so.2 — Provide hostname resolution for the locally configured system hostname.
nss-myhostname is a plugin 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).
localhost" is resolved to
the IP addresses 127.0.0.1 and
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
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 unncessary, and on
many systems the file becomes entirely optional.
To activate the NSS modules,
myhostname" has to be added to the
line starting with "
It is recommended to place
myhostname" last in the
nsswitch.conf line to make sure
that this mapping is only used as fallback, and any
/etc/hosts based mapping
Here's an example
/etc/nsswitch.conf file, that
passwd: compat group: compat shadow: compat hosts: files dns mymachines 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