12-30-2006
Quote:
Originally Posted by smanu
I have come across a fact that /etc/resolv.conf can be overrided by using ~/.nslookuprc.
Is this completely true...i.e can I completely override /etc/resolv.conf.
No, it is almost totally false.
When you give a command like "telnet this.that.com", the telnet command must convert this.that.com to an ip address. To do that, the telnet program will call some subroutines that are called the resolver. The resolver will read /etc/resolv.conf (assuming that the box is configured to use DNS). But the resolver does not know about .nslookuprc and will ignore it completely.
Meanwhile, there is a program called nslookup which is sometimes used to debug DNS issues. nslookup is the first widespread DNS tool. It (unfairly I think) has a reputation as a poor tool. Many people have moved on to "dig" which is a more powerful DNS tool. But some folks still use nslookup. nslookup does not use the resolver. But it sometimes peeks at /etc/resolv.conf directly. nslookup is the only program that knows about .nslookuprc. If you put enough stuff in .nslookuprc, nslookup will not need to peek at /etc/resolv.conf. In this sense alone can .nslookuprc override /etc/resolv.conf.
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LEARN ABOUT NETBSD
resolvconf.conf
RESOLVCONF.CONF(5) System Manager's Manual RESOLVCONF.CONF(5)
NAME
resolvconf.conf -- resolvconf configuration file
DESCRIPTION
resolvconf.conf is the configuration file for resolvconf(8). The resolvconf.conf file is a shell script that is sourced by resolvconf(8),
meaning that resolvconf.conf must contain valid shell commands. Listed below are the standard resolvconf.conf variables that may be set.
After updating this file, you may wish to run resolvconf -u to apply the new configuration.
RESOLVCONF OPTIONS
interface_order
These interfaces will always be processed first. If unset, defaults to the following:-
lo lo[0-9]*
dynamic_order
These interfaces will be processed next, unless they have a metric. If unset, defaults to the following:-
tap[0-9]* tun[0-9]* vpn vpn[0-9]* ppp[0-9]* ippp[0-9]*
search_domains
Prepend search domains to the dynamically generated list.
search_domains_append
Append search domains to the dynamically generated list.
name_servers
Prepend name servers to the dynamically generated list. You should set this to 127.0.0.1 if you use a local name server other than
libc.
name_servers_append
Append name servers to the dynamically generated list.
private_interfaces
These interfaces name servers will only be queried for the domains listed in their resolv.conf. Useful for VPN domains. This is
equivalent to the resolvconf -p option.
state_dir
Override the default state directory of /var/run/resolvconf. This should not be changed once resolvconf is in use unless the old
directory is copied to the new one.
LIBC OPTIONS
The following variables affect resolv.conf(5) directly:-
resolv_conf
Defaults to /etc/resolv.conf if not set.
resolv_conf_options
A list of libc resolver options, as specified in resolv.conf(5).
resolv_conf_passthrough
When set to YES the latest resolv.conf is written to resolv_conf without any alteration.
resolv_conf_sortlist
A libc resolver sortlist, as specified in resolv.conf(5).
SUBSCRIBER OPTIONS
openresolv ships with subscribers for the name servers dnsmasq(8), named(8), pdnsd(8) and unbound(8). Each subscriber can create configura-
tion files which should be included in in the subscribers main configuration file.
dnsmasq_conf
This file tells dnsmasq which nameservers to use for specific domains.
dnsmasq_resolv
This file tells dnsmasq which nameservers to use for global lookups.
Example resolvconf.conf for dnsmasq:
nameservers=127.0.0.1
dnsmasq_conf=/etc/dnsmasq-conf.conf
dnsmasq_resolv=/etc/dnsmasq-resolv.conf
Example dnsmasq.conf:
listen-address=127.0.0.1
conf-file=/etc/dnsmasq-conf.conf
resolv-file=/etc/dnsmasq-resolv.conf
named_options
Include this file in the named options block. This file tells named which nameservers to use for global lookups.
named_zones
Include this file in the named global scope, after the options block. This file tells named which nameservers to use for specific
domains.
Example resolvconf.conf for named:
nameservers=127.0.0.1
named_options=/etc/named-options.conf
named_zones=/etc/named-zones.conf
Example named.conf:
options {
listen-on { 127.0.0.1; };
include /etc/named-options.conf;
};
include /etc/named-zones.conf;
pdnsd_conf
This is the main pdnsd configuration file which we modify to add our forward domains to. If this variable is not set then we rely on
the pdnsd configuration file setup to read pdnsd_resolv as documented below.
pdnsd_resolv
This file tells pdnsd about global nameservers. If this variable is not set then it's written to pdnsd_conf.
Example resolvconf.conf for pdnsd:
nameservers=127.0.0.1
pdnsd_conf=/etc/pdnsd.conf
# pdnsd_resolv=/etc/pdnsd-resolv.conf
Example pdnsd.conf:
global {
server_ip = 127.0.0.1;
status_ctl = on;
}
server {
# A server definition is required, even if emtpy.
label="empty";
proxy_only=on;
# file="/etc/pdnsd-resolv.conf";
}
unbound_conf
This file tells unbound about specific and global nameservers.
Example resolvconf.conf for unbound:
nameservers=127.0.0.1
unbound_conf=/etc/unbound-resolvconf.conf
Example unbound.conf:
include: /etc/unbound-resolvconf.conf
SEE ALSO
resolv.conf(5) and resolvconf(8).
AUTHORS
Roy Marples <roy@marples.name>
BUGS
Please report them to http://roy.marples.name/projects/openresolv
BSD
August 11, 2011 BSD