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Files Reference
netsvc.conf File
Purpose
Specifies the ordering of certain name resolution services.
Description
The /etc/netsvc.conf file is used to specify the
ordering of name resolution for the sendmail command, gethostbyname subroutine, gethostaddr subroutine,
and gethostent subroutine and alias resolution for the sendmail command.
Several mechanisms for resolving host names and aliases are available.
The gethostbyname, gethostbyaddr,
and gethostent subroutines use these mechanisms for
resolving names. A default order exists in which the resolver subroutines
try the mechanisms for resolving host names and Internet Protocol (IP) addresses.
Resolving Host Names
You can override the default order and the order given in the /etc/irs.conf file by creating the /etc/netsvc.conf configuration file and specifying the desired ordering. To specify this
host ordering, create an entry in the following format:
hosts = value [, value]
Use one or more of the following values for the hosts keyword:
Value |
Description |
auth |
Designates the specified server as authoritative. A resolver does not continue searching for host names further than
an authoritative server. For example, when two services are given as values
for the host keyword and the first service is made authoritative,
and if the resolver cannot find the host name in the authoritative service,
then the resolver terminates its search. However, the auth option has no effect if the resolver is unable to contact the authoritative
server; in this case, the resolver continues to search the next service given
in the same entry.
Indicate that the specified service is authoritative
by following it by an = and then auth.
Note
The auth option is only valid when used in
conjunction with a service value for the host keyword. |
bind |
Uses BIND/DNS services for resolving names |
local |
Searches the local /etc/hosts file for resolving
names |
nis |
Uses NIS services for resolving names. NIS must be running if you
specify this option |
ldap |
Uses LDAP services for resolving names. This option works if LDAP
server schema is IBM Secureway Directory compliant.
Note
Although
still supported, the use of ldap mechanism is deprecated.
Use of nis_ldap mechanism instead is recommended. |
nis_ldap |
Uses LDAP services for resolving names. This option
works if LDAP server schema is RFC 2307 compliant. |
bind4 |
Uses BIND/DNS services for resolving only IPv4 addresses |
bind6 |
Uses BIND/DNS services for resolving only IPv6 addresses |
local4 |
Searches the local /etc/hosts file for resolving
only IPv4 addresses |
local6 |
Searches the local /etc/hosts file for resolving
only IPv6 addresses |
nis4 |
Uses NIS services for resolving only IPv4 addresses |
nis6 |
Uses NIS services for resolving only IPv6 addresses |
ldap4 |
Uses LDAP services for resolving only IPv4 addresses |
ldap6 |
Uses LDAP services for resolving only IPv6 addresses |
The environment variable NSORDER overrides the host
settings in the /etc/netsvc.conf file, which in turn
overrides the host settings in the /etc/irs.conf file.
Resolving Aliases
The sendmail command searches the local /etc/aliases file, or uses NIS if specified for resolving aliases. You
can override the default by specifying how to resolve aliases in the /etc/netsvc.conf file. To specify alias ordering to the sendmail command, enter the following:
alias = value [, value]
Use one or more of the following values for the alias keyword:
Value |
Description |
files |
Searches the local /etc/aliases file for the
alias |
nis |
Uses NIS services for resolving alias |
The order is specified on one line with values separated by commas. White
spaces are permitted around the commas and the equal sign. The values specified
and their ordering are dependent on the network configuration.
Examples
- To use only the /etc/hosts file for resolving names,
enter:
hosts = local
- If the resolver cannot find the name in the /etc/hosts file and you want to the resolver to use NIS, enter:
hosts = local , nis
- To use the LDAP server for resolving names, indicate that it is authoritative,
and to also use the BIND service, enter:
hosts = ldap = auth , bind
In this example, if the resolver cannot contact the LDAP server,
then it searches the BIND service.
- To override the default order and use only NIS for resolving aliases by
the sendmail command, enter:
aliases = nis
Files
/etc/netsvc.conf |
Specifies the path to the file. |
Related Information
The aliases file for mail,
irs.conf file, hosts file format for TCP/IP.
The sendmail command.
The gethostbyname subroutine, gethostbyaddr subroutine,
and gethostent subroutine.
TCP/IP Name Resolution in AIX 5L Version 5.2 System Management Guide: Communications and Networks
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