Own Your DNS Data

Install and Configure Your DNS Server

So, even when you rule out pure DNS caching software, there still are a number of different DNS servers you can choose from, including BIND, djbdns and unbound, among others. I personally have the most experience with BIND, so that's what I prefer, but any of those would do the job. The nice thing about BIND, particularly in the case of the Debian and Ubuntu packages, is that all you need to do is run:


$ sudo apt-get install bind9

and after the software installs, BIND automatically is configured to act as a local recursive DNS server for your internal network. The procedure also would be the same if you were to set this up on a spare Raspberry Pi running the Raspbian distribution. On other Linux distributions, the package may just be called bind.

If BIND isn't automatically configured as a local recursive DNS server on your particular Linux distribution and doesn't appear to work out of the box, just locate the options section of your BIND config (often in /etc/bind/named.conf, /etc/bind/named.conf.options or /etc/named/named.conf, depending on the distribution), and if you can't seem to perform recursive queries, add the following line under the options{} section:


options {
  allow-recursion { 10/8; 172.16/12; 192.168/16; 127.0.0.1; };
. . .
}

This change allows any hosts on those networks (internal RFC1918 IP addresses) to perform recursive queries on your name server without allowing the world to do so.

Once you have BIND installed, you'll want to test it. If you installed BIND on your local machine, you could test this out with the dig command:


$ dig @localhost www.linuxjournal.com
; <<>> DiG 9.8.1-P1 <<>> @localhost www.linuxjournal.com
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 17485
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 0

;; QUESTION SECTION:
;www.linuxjournal.com.         IN   A

;; ANSWER SECTION:
www.linuxjournal.com.   1800   IN   A   76.74.252.198

;; AUTHORITY SECTION:
linuxjournal.com.       30479  IN   NS  ns66.domaincontrol.com.
linuxjournal.com.       30479  IN   NS  ns65.domaincontrol.com.

;; Query time: 31 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Wed Dec 18 09:37:13 2013
;; MSG SIZE  rcvd: 106

Otherwise, replace localhost with the IP address of your Raspberry Pi or whatever machine on which you installed BIND. To use this name server for all of your requests, update your /etc/resolv.conf file so that it contains:


nameserver 127.0.0.1

as its only nameserver line. Replace 127.0.0.1 with the IP address of the machine you installed BIND on if it isn't on the same machine. On some modern distributions, there are external tools that tweak /etc/resolv.conf for you, so in those cases, you may have to edit your dhclient.conf or other network configuration files so that you can override the provided list of name servers. Once you do that though, really that's all there is to it. Now you can use DNS knowing that all of your DNS search data sits on a machine under your control.

______________________

Kyle Rankin is SVP of Security and Infrastructure at Zero, the author of many books including Linux Hardening in Hostile Networks, DevOps Troubleshooting and The Official Ubuntu Server Book, and a columnist for Linux Journal. Follow him @kylerankin