NSS-MYHOSTNAME(8)

NAME
nss-myhostname - Provide hostname resolution for the locally configured system hostname.

SYNOPSIS

nss-myhostname.la

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)