A first stab at DNS config, very useful for dialup users.
A caching only name server will find the answer to name queries and remember the answer the next time you need it. This will shorten the waiting time the next time significantly, especially if you're on a slow connection.
First you need a file called /etc/namedb/named.conf
. This is
read when named starts. For now it should simply contain:
// Config file for caching only name server options { directory "/etc/namedb"; // Uncommenting this might help if you have to go through a // firewall and things are not working out: // query-source port 53; }; zone "." { type hint; file "root.hints"; }; zone "0.0.127.in-addr.arpa" { type master; file "localhost.rev"; };
The `directory
' line tells named where to look for files. All
files named subsequently will be relative to this.
/etc/namedb
is the standard directory
according to the hier(7) manpage.
The file named /etc/namedb/named.root
is named in this.
/etc/namedb/named.root
should contain something simular to this:
; ; There might be opening comments here if you already have this file. ; If not don't worry. ; . 6D IN NS G.ROOT-SERVERS.NET. . 6D IN NS J.ROOT-SERVERS.NET. . 6D IN NS K.ROOT-SERVERS.NET. . 6D IN NS L.ROOT-SERVERS.NET. . 6D IN NS M.ROOT-SERVERS.NET. . 6D IN NS A.ROOT-SERVERS.NET. . 6D IN NS H.ROOT-SERVERS.NET. . 6D IN NS B.ROOT-SERVERS.NET. . 6D IN NS C.ROOT-SERVERS.NET. . 6D IN NS D.ROOT-SERVERS.NET. . 6D IN NS E.ROOT-SERVERS.NET. . 6D IN NS I.ROOT-SERVERS.NET. . 6D IN NS F.ROOT-SERVERS.NET. G.ROOT-SERVERS.NET. 5w6d16h IN A 192.112.36.4 J.ROOT-SERVERS.NET. 5w6d16h IN A 198.41.0.10 K.ROOT-SERVERS.NET. 5w6d16h IN A 193.0.14.129 L.ROOT-SERVERS.NET. 5w6d16h IN A 198.32.64.12 M.ROOT-SERVERS.NET. 5w6d16h IN A 202.12.27.33 A.ROOT-SERVERS.NET. 5w6d16h IN A 198.41.0.4 H.ROOT-SERVERS.NET. 5w6d16h IN A 128.63.2.53 B.ROOT-SERVERS.NET. 5w6d16h IN A 128.9.0.107 C.ROOT-SERVERS.NET. 5w6d16h IN A 192.33.4.12 D.ROOT-SERVERS.NET. 5w6d16h IN A 128.8.10.90 E.ROOT-SERVERS.NET. 5w6d16h IN A 192.203.230.10 I.ROOT-SERVERS.NET. 5w6d16h IN A 192.36.148.17 F.ROOT-SERVERS.NET. 5w6d16h IN A 192.5.5.241
The file describes the root name servers in the world. This changes over time and must be maintained. See the maintenance section for how to keep it up to date.
The next section in named.conf
is the last zone
. I will
explain its use in a later chapter, for now just make this a file
named localhost.rev
in the subdirectory etc/namedb/:
@ IN SOA ns.freebsd.bogus. hostmaster.freebsd.bogus. ( 1 ; Serial 8H ; Refresh 2H ; Retry 1W ; Expire 1D) ; Minimum TTL NS ns.freebsd.bogus. 1 PTR localhost.
Next, you need a /etc/resolv.conf
looking something like
this:
search subdomain.your-domain.edu your-domain.edu nameserver 127.0.0.1
The `search
' line specifies what domains should be searched
for any host names you want to connect to. The `nameserver
' line
specifies the address of your nameserver, in this case your own
machine since that is where your named runs (127.0.0.1 is right, no
matter if your machine has an other address too). If you want to list
several name servers put in one `nameserver
' line for
each. (Note: Named never reads this file, the resolver that uses named
does.)
To illustrate what this file does: If a client tries to look up
foo
, then foo.subdomain.your-domain.edu
is tried
first, then foo.your-fomain.edu
, finally foo
. If a
client tries to look up sunsite.unc.edu
,
sunsite.unc.edu.subdomain.your-domain.edu
is tried first
(yes, it's silly, but that's the way it works), then
sunsite.unc.edu.your-domain.edu
, and finally
sunsite.unc.edu
. You may not want to put in too many domains
in the search line, it takes time to search them all.
The example assumes you belong in the domain
subdomain.your-domain.edu
, your machine then, is probably
called your-machine.subdomain.your-domain.edu
. The search
line should not contain your TLD (Top Level Domain, `edu
' in this
case). If you frequently need to connect to hosts in another domain
you can add that domain to the search line like this:
search subdomain.your-domain.edu your-domain.edu other-domain.com
and so on. Obviously you need to put real domain names in instead. Please note the lack of periods at the end of the domain names. This is important, please note the lack of periods at the end of the domain names.
Next, depending on your libc version you either need to fix
/etc/nsswitch.conf
or /etc/host.conf
. If you
already have nsswitch.conf
that's what we'll fix, if not, we'll
fix host.conf
.
/etc/nsswitch.conf
This is a long file specifying where to get different kinds of data
types, from what file or database. It usually contains helpful
comments at the top, which you should consider reading. After that
find the line starting with `hosts:
', it should read
hosts: files dns
If there is no line starting with `hosts:
' then put in the one
above. It says that programs should first look in the
/etc/hosts
file, then check DNS according to
resolv.conf
.
/etc/host.conf
It probably contains several lines, one should start with
order
and it should look like this:
order hosts,bind
If there is no `order
' line you should add one. It tells the
host name resolving routines to first look in /etc/hosts
,
then ask the name server (which you in resolv.conf
said is at
127.0.0.1).