Provided by: libnss-myhostname_229-4ubuntu4_amd64
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). · The hostname "localhost" (as well as any hostname ending in ".localhost", ".localdomain" or equal to "localdomain") is 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, "myhostname" has to be added to the line starting with "hosts:" in /etc/nsswitch.conf. It is recommended to place "myhostname" last in the nsswitch.conf line to make sure that this mapping is only used as fallback, and that any DNS or /etc/hosts based mapping takes precedence.
Here is an example /etc/nsswitch.conf file that enables myhostname correctly: passwd: compat mymachines group: compat mymachines shadow: compat hosts: files resolve 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 omega.
systemd(1), nss-resolve(8), nss-mymachines(8), nsswitch.conf(5), getent(1)