1NSS-MYHOSTNAME(8)               nss-myhostname               NSS-MYHOSTNAME(8)
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NAME

6       nss-myhostname, libnss_myhostname.so.2 - Provide hostname resolution
7       for the locally configured system hostname.
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SYNOPSIS

10       libnss_myhostname.so.2
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DESCRIPTION

13       nss-myhostname is a plugin for the GNU Name Service Switch (NSS)
14       functionality of the GNU C Library (glibc) primarily providing hostname
15       resolution for the locally configured system hostname as returned by
16       gethostname(2). The precise hostnames resolved by this module are:
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18       ·   The local, configured hostname is resolved to all locally
19           configured IP addresses ordered by their scope, or — if none are
20           configured — the IPv4 address 127.0.0.2 (which is on the local
21           loopback) and the IPv6 address ::1 (which is the local host).
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23       ·   The hostname "localhost" is resolved to the IP addresses 127.0.0.1
24           and ::1.
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26       ·   The hostname "gateway" is resolved to all current default routing
27           gateway addresses, ordered by their metric. This assigns a stable
28           hostname to the current gateway, useful for referencing it
29           independently of the current network configuration state.
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31       Various software relies on an always-resolvable local hostname. When
32       using dynamic hostnames, this is traditionally achieved by patching
33       /etc/hosts at the same time as changing the hostname. This is
34       problematic since it requires a writable /etc file system and is
35       fragile because the file might be edited by the administrator at the
36       same time. With nss-myhostname enabled changing /etc/hosts is
37       unncessary, and on many systems the file becomes entirely optional.
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39       To activate the NSS modules, "myhostname" has to be added to the line
40       starting with "hosts:" in /etc/nsswitch.conf.
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42       It is recommended to place "myhostname" last in the nsswitch.conf line
43       to make sure that this mapping is only used as fallback, and any DNS or
44       /etc/hosts based mapping takes precedence.
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EXAMPLE

47       Here's an example /etc/nsswitch.conf file, that enables myhostname
48       correctly:
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50           passwd:   compat
51           group:    compat
52           shadow:   compat
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54           hosts:    files dns mymachines myhostname
55           networks:       files
56
57           protocols:      db files
58           services:       db files
59           ethers:   db files
60           rpc:      db files
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62           netgroup:       nis
63
64       To test, use glibc's getent tool:
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66           $ getent ahosts `hostname`
67           ::1       STREAM omega
68           ::1       DGRAM
69           ::1       RAW
70           127.0.0.2       STREAM
71           127.0.0.2       DGRAM
72           127.0.0.2       RAW
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74       In this case the local hostname is omega.
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SEE ALSO

77       systemd(1), nss-mymachines(8), nsswitch.conf(5), getent(1)
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81systemd 219                                                  NSS-MYHOSTNAME(8)
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