Description¶

nss-myhostname is a plugin for the GNU Name Service Switch (NSS) functionality of the GNU C Library (glibc) providing hostname resolution for the locally configured system hostname as returned by gethostname(2). Various software relies on an always-resolvable local hostname. When using dynamic hostnames, this is usually achieved by patching /etc/hosts at the same time as changing the host name. This however is not ideal since it requires a writable /etc file system and is fragile because the file might be edited by the administrator at the same time. nss-myhostname simply returns all locally configured public IP addresses, 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) for whatever system hostname is configured locally. Patching /etc/hosts is thus no longer necessary.

To activate the NSS modules, myhostname has to be added to the line starting with "hosts:" in /etc/nsswitch.conf

It is recommended to put myhostname last in the nsswitch.conf line to make sure that this mapping is only used as fallback, and any DNS or /etc/hosts based mapping takes precedence.

Example¶

# /etc/nsswitch.conf

passwd:         compat
group:          compat
shadow:         compat

hosts:          files 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 Also¶

systemd(1), systemd-logind.service(8), logind.conf(5), loginctl(1), pam.conf(5), pam.d(5), pam(8), pam_loginuid(8)