Nsswitch: Name Resolution Service

Nsswitch: Name Resolution Service

App->nsswitch->resolve_lib

Libnss

/ETC/NSSWITCH.CONF Master configuration file

# Example:

#passwd: DB Files Nisplus NIS

#shadow: DB Files Nisplus NIS

#group: DB Files Nisplus NIS

Passwd:files

Shadow:files

Group:files

#hosts: DB Files Nisplus NIS DNS

Hosts:files DNS

# Example-obey only what Nisplus tells us ...

#services: Nisplus [Notfound=return] Files

#networks: Nisplus [Notfound=return] Files

#protocols: Nisplus [Notfound=return] Files

#rpc: Nisplus [Notfound=return] Files

#ethers: Nisplus [Notfound=return] Files

#netmasks: Nisplus [Notfound=return] Files

Nisplus return Value:

SUCCESS Service Ok,found name is healthy and goes to a value

NOTFOUND service Ok,name not found normal, name not converted to value

Unavaail Service not available services not found, when Unacaail will find files

Tryagain temporary service failure temporary failure, try again

Bootparams:nisplus [Notfound=return] Files

Ethers:files

Netmasks:files

Networks:files

Protocols:files

Rpc:files

Services:files

Netgroup:nisplus

Publickey:nisplus

Automount:files Nisplus

Aliases:files Nisplus

[Email protected] lib]# Vim/etc/protocols

[Email protected] ~]# vim/etc/services

Name Resolution Service:

Nsswitch call the corresponding library file in/usr/lib to parse

Getent get all entries for a library in Nsswitch

[Email protected] ~]# getent passwd

[Email protected] ~]# getent passwd Root

Root:x:0:0:root:/root:/bin/bash

[Email protected] ~]# Getent hosts

127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4

127.0.0.1 localhost localhost.localdomain localhost6 localhost6.localdomain6

[[email protected] ~]# getent hosts www.baidu.com first go to the hosts if no more DNS to find

180.97.33.107 www.a.shifen.com www.baidu.com

180.97.33.108 www.a.shifen.com www.baidu.com

This article from "Operation and maintenance Growth Road" blog, declined reprint!

Nsswitch: Name Resolution Service