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## 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)