Difference between revisions of "DNS server unique zone"

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The DNS [Domain Name System] is a key component of a network infrastructure. '''It allows you to use NAMES''' instead of IP addresses and technical garbage.
+
[[Category:Linux]]
  
−
You can learn how it works through a simple Google request.  
+
Here, I will present the installation of:
 +
* Local domain (.local)
  
 +
That means '''all the INTERNAL resources are private'''. Nothing is reachable from the outside.
  
−
Here, I will focus on the '''installation of a DNS primary server''' (= DNS for domain smartcards.local) using ''BIND9''.
 
  
  
 +
In the following example I'll be using:
 +
* INTERNAL zone: ''smartcards.'''local'''''
 +
* DNS server name: ''smartcard-gw''
 +
* Network: 172.16.50.0/24 ; router: 172.16.50.1 ; DNS server IP: 172.16.50.2
  
−
=Setup=
+
 
 +
 
 +
=Zone configuration (name to IP @)=
 +
 
 +
==Declare the new zone==
 +
 
 +
Edit configuration file:
  
 
<syntaxhighlight lang="bash">
 
<syntaxhighlight lang="bash">
−
apt-get install bind9 dnsutils bind9-doc
+
vim /etc/bind/named.conf.local
 +
</syntaxhighlight>
 +
 
 +
 
 +
Uncomment and adjust the file content
 +
 
 +
<syntaxhighlight lang="apache">
 +
zone "smartcards.local" {
 +
type master;
 +
        file "/etc/bind/smartcards.local";
 +
};
 
</syntaxhighlight>
 
</syntaxhighlight>
  
  
  
−
=Primary master=
+
==Zone configuration file==
 +
 
 +
 
 +
Create the zone configuration file from a local template:
 +
 
 +
<syntaxhighlight lang="bash">
 +
cp /etc/bind/db.local /etc/bind/smartcards.local
 +
</syntaxhighlight>
 +
 
 +
 
 +
Edit configuration file:
 +
 
 +
<syntaxhighlight lang="bash">
 +
vim /etc/bind/smartcards.local
 +
</syntaxhighlight>
 +
 
 +
 
 +
Adjust the file content
 +
 
 +
<syntaxhighlight lang="apache">
 +
;
 +
; BIND data file for smartcards.local
 +
;
 +
$TTL    604800
 +
@      IN      SOA    smartcard-gw.smartcards.local. root.smartcards.local. (
 +
                      20140603        ; Serial
 +
                                        ; As the serial be changed everytime you edit this file
 +
                                        ; it is recommended to use the pattern "yyyyMMdd"
 +
                        604800        ; Refresh
 +
                          86400        ; Retry
 +
                        2419200        ; Expire
 +
                        604800 )      ; Negative Cache TTL
 +
 
 +
;
 +
; DNS server declaration
 +
; Each NS must point to an A record, not a CNAME.
 +
; This is where the Primary and Secondary DNS servers are defined
 +
;
 +
@                IN      NS      smartcard-gw.smartcards.local.
 +
smartcard-gw    IN      A      172.16.50.2
 +
 
 +
;
 +
; Gateway (router)
 +
;
 +
cisco-router      IN      A      172.16.50.1
 +
 
 +
;
 +
; Declare your servers and networks hosts
 +
;
 +
smarcartd-prod-00 IN      A      172.16.50.50
 +
smarcartd-prod-01 IN      A      172.16.50.51
 +
smarcartd-prod-02 IN      A      172.16.50.52
 +
smarcartd-prod-03 IN      A      172.16.50.53
 +
 
 +
; Create an alias to an existing record
 +
;wwww            IN      CNAME  smartcard-gw
 +
 
 +
</syntaxhighlight>
  
−
A DNS primary master is the main DNS for your local domain (ex: smartcards.local).
 
  
  
−
These are the steps to do:
+
Notes:
−
* '''Set the external DNS''' to use by your server
 
−
**File: /etc/bind/named.conf.options
 
  
−
* '''Declare the new domain''' to manage
+
* Don't forget to adjust the serial every-time you edit the file !
−
** File: /etc/bind/named.conf.local
 
  
−
* Create a '''dedicated configuration file''' for the new domain
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* NS = Name server
−
** New file: /etc/bind/smartcards.local
 
  
−
* Adjust the '''reverse zone'''
+
* A = IP v4 entry
−
** Rename and adjust file: /etc/bind/db.192
 
  
 +
* AAAA = IP v6 entry
  
−
==Set the external DNS==
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* CNAME = Alias to a previous A or AAAA entry
  
−
This is the list of DNS your server will use to populate its own cache.
 
  
  
−
The external DNS can either be your ISP's DNS or Google's servers.
+
=Reverse zone (IP @ to name)=
  
−
!! Mind the order !!
+
Now that the zone is setup and resolving names to IP Adresses a '''Reverse zone''' is also required. A Reverse zone allows DNS to resolve an address to a name.
−
First DNS have a higher priority.
 
  
 +
 +
===Declare reverse zone===
  
  
Line 50: Line 123:
  
 
<syntaxhighlight lang="bash">
 
<syntaxhighlight lang="bash">
−
vim /etc/bind/named.conf.options
+
vim /etc/bind/named.conf.local
 +
</syntaxhighlight>
 +
 
 +
 
 +
Add the following reverse
 +
 
 +
<syntaxhighlight lang="apache">
 +
# Our reverse zone
 +
# Server IP 172.16.50.2
 +
zone "50.16.172.in-addr.arpa" {
 +
        type master;
 +
        file "/etc/bind/db.172";
 +
};
 +
</syntaxhighlight>
 +
 
 +
 
 +
Key points:
 +
 
 +
* Replace ''50.16.172'' with the '''first three octets''' of whatever network you are using - '''in reverse order'''!
 +
 
 +
* Name the zone file /etc/bind/''db.172'' : it should match the '''first octet''' of your network.
 +
 
 +
 
 +
 
 +
==Configure reverse zone==
 +
 
 +
 
 +
Now create the /etc/bind/db.172 file:
 +
 
 +
<syntaxhighlight lang="bash">
 +
cp /etc/bind/db.127 /etc/bind/db.172
 +
</syntaxhighlight>
 +
 
 +
 
 +
Edit the new file:
 +
 
 +
<syntaxhighlight lang="bash">
 +
vim /etc/bind/db.172
 +
</syntaxhighlight>
 +
 
 +
 
 +
The content is basically the same as /etc/bind/smartcards.local:
 +
<syntaxhighlight lang="apache">
 +
;
 +
; BIND reverse data file for local 172.16.50.XXX net
 +
;
 +
$TTL    604800
 +
@      IN      SOA    smartcard-gw.smartcards.local. root.smartcards.local. (
 +
                      20140603        ; Serial
 +
                                        ; As the serial be changed everytime you edit this file
 +
                                        ; it is recommended to use the pattern "yyyyMMdd"
 +
                        604800        ; Refresh
 +
                          86400        ; Retry
 +
                        2419200        ; Expire
 +
                        604800 )      ; Negative Cache TTL
 +
;
 +
; Local server
 +
;
 +
@      IN      NS      smartcard-gw.
 +
2      IN      PTR    smartcard-gw.smartcards.local.
 +
 
 +
; Gateway (router)
 +
1      IN      PTR    cisco-router.smartcards.local
 +
 
 +
;
 +
; Other components and hosts
 +
;
 +
50      IN      PTR    smartcard-prod-00.smartcards.local.
 +
51      IN      PTR    smartcard-prod-01.smartcards.local.
 +
52      IN      PTR    smartcard-prod-02.smartcards.local.
 +
53      IN      PTR    smartcard-prod-03.smartcards.local.
 +
 
 +
</syntaxhighlight>
 +
 
 +
 
 +
Notes:
 +
 
 +
* Don't forget to adjust the serial every-time you edit the file !
 +
 
 +
* You only need to put the last byte value in the reverse
 +
 
 +
* PTR = redirection to A entry
 +
 
 +
 
 +
 
 +
=Take changes into account=
 +
 
 +
 
 +
<syntaxhighlight lang="bash">
 +
service bind9 restart
 +
</syntaxhighlight>
 +
 
 +
 
 +
 
 +
 
 +
 
 +
=Add new hostname=
 +
 
 +
 
 +
This is how we had a new host-name into the network:
 +
 
 +
 
 +
==Update LOCAL zone==
 +
 
 +
 
 +
Edit local zone:
 +
 
 +
<syntaxhighlight lang="bash">
 +
vim /etc/bind/smartcards.local
 +
</syntaxhighlight>
 +
 
 +
 
 +
Add a A or AAAA entry:
 +
 
 +
<syntaxhighlight lang="apache">
 +
my-new-host      IN      A      172.16.50.60
 
</syntaxhighlight>
 
</syntaxhighlight>
  
  
−
Adjust the file content
+
 
 +
==Update REVERSE zone==
 +
 
 +
 
 +
Edit local zone:
  
 
<syntaxhighlight lang="bash">
 
<syntaxhighlight lang="bash">
−
forwarders {
+
vim /etc/bind/db.172
−
    # Local gateway or router
+
</syntaxhighlight>
−
    192.168.1.1;
 
  
−
    # Your ISP DNS IP’s
 
−
    182.176.39.23;
 
−
    182.176.18.13;
 
  
−
    # Google's DNS
+
Add a A or AAAA entry:
−
     8.8.8.8
+
 
−
    8.8.4.4
+
<syntaxhighlight lang="apache">
−
};
+
60      IN     PTR    my-new-host.smartcards.local.
 +
</syntaxhighlight>
 +
 
 +
 
 +
 
 +
==Restart service==
 +
 
 +
<syntaxhighlight lang="bash">
 +
service bind9 restart
 
</syntaxhighlight>
 
</syntaxhighlight>
  
  
  
−
==Declare the new domain==
 
  
  
  
 +
=Sources=
 +
 +
You can find a lot of information about DNS on the web. I used the following tutorials:
 +
 +
* https://help.ubuntu.com/community/BIND9ServerHowto
 +
 +
* https://help.ubuntu.com/14.04/serverguide/dns-references.html#dns-record-types
 +
 +
* https://help.ubuntu.com/14.04/serverguide/dns-configuration.html
 +
 +
* http://blog.bobbyallen.me/2013/09/19/setting-up-internal-dns-on-ubuntu-server-12-04-lts/
  
−
==Domain configuration file==
+
* http://doc.ubuntu-fr.org/bind9  (in French)
  
  
 +
Bug fixes:
  
−
==Reverse zone file==
+
* no forwarding due to DNS-SEC errors (broken trust chain): http://pewetheb.blogspot.se/2013/11/named-error-broken-trust-chain.html

Latest revision as of 14:16, 22 August 2014


Here, I will present the installation of:

  • Local domain (.local)

That means all the INTERNAL resources are private. Nothing is reachable from the outside.


In the following example I'll be using:

  • INTERNAL zone: smartcards.local
  • DNS server name: smartcard-gw
  • Network: 172.16.50.0/24 ; router: 172.16.50.1 ; DNS server IP: 172.16.50.2


Zone configuration (name to IP @)

Declare the new zone

Edit configuration file: 

vim /etc/bind/named.conf.local


Uncomment and adjust the file content 

zone "smartcards.local" {
	type master;
        file "/etc/bind/smartcards.local";
};


Zone configuration file

Create the zone configuration file from a local template: 

cp /etc/bind/db.local /etc/bind/smartcards.local


Edit configuration file: 

vim /etc/bind/smartcards.local


Adjust the file content 

;
; BIND data file for smartcards.local
;
$TTL    604800
@       IN      SOA     smartcard-gw.smartcards.local. root.smartcards.local. (
                       20140603         ; Serial
                                        ; As the serial be changed everytime you edit this file
                                        ; it is recommended to use the pattern "yyyyMMdd"
                         604800         ; Refresh
                          86400         ; Retry
                        2419200         ; Expire
                         604800 )       ; Negative Cache TTL

; 
; DNS server declaration
; Each NS must point to an A record, not a CNAME. 
; This is where the Primary and Secondary DNS servers are defined
;
@                IN      NS      smartcard-gw.smartcards.local.
smartcard-gw     IN      A       172.16.50.2

;
; Gateway (router)
;
cisco-router      IN      A       172.16.50.1

;
; Declare your servers and networks hosts 
;
smarcartd-prod-00 IN      A       172.16.50.50
smarcartd-prod-01 IN      A       172.16.50.51
smarcartd-prod-02 IN      A       172.16.50.52
smarcartd-prod-03 IN      A       172.16.50.53

; Create an alias to an existing record
;wwww             IN      CNAME   smartcard-gw


Notes:

  • Don't forget to adjust the serial every-time you edit the file !
  • NS = Name server
  • A = IP v4 entry
  • AAAA = IP v6 entry
  • CNAME = Alias to a previous A or AAAA entry


Reverse zone (IP @ to name)

Now that the zone is setup and resolving names to IP Adresses a Reverse zone is also required. A Reverse zone allows DNS to resolve an address to a name.


Declare reverse zone

Edit configuration file: 

vim /etc/bind/named.conf.local


Add the following reverse 

# Our reverse zone
# Server IP 172.16.50.2
zone "50.16.172.in-addr.arpa" {
        type master;
        file "/etc/bind/db.172";
};


Key points:

  • Replace 50.16.172 with the first three octets of whatever network you are using - in reverse order!
  • Name the zone file /etc/bind/db.172 : it should match the first octet of your network.


Configure reverse zone

Now create the /etc/bind/db.172 file: 

cp /etc/bind/db.127 /etc/bind/db.172


Edit the new file: 

vim /etc/bind/db.172


The content is basically the same as /etc/bind/smartcards.local: 

;
; BIND reverse data file for local 172.16.50.XXX net
;
$TTL    604800
@       IN      SOA     smartcard-gw.smartcards.local. root.smartcards.local. (
                       20140603         ; Serial
                                        ; As the serial be changed everytime you edit this file
                                        ; it is recommended to use the pattern "yyyyMMdd"
                         604800         ; Refresh
                          86400         ; Retry
                        2419200         ; Expire
                         604800 )       ; Negative Cache TTL
;
; Local server
;
@       IN      NS      smartcard-gw.
2       IN      PTR     smartcard-gw.smartcards.local.

; Gateway (router)
1       IN      PTR     cisco-router.smartcards.local

;
; Other components and hosts
;
50       IN      PTR     smartcard-prod-00.smartcards.local.
51       IN      PTR     smartcard-prod-01.smartcards.local.
52       IN      PTR     smartcard-prod-02.smartcards.local.
53       IN      PTR     smartcard-prod-03.smartcards.local.


Notes:

  • Don't forget to adjust the serial every-time you edit the file !
  • You only need to put the last byte value in the reverse
  • PTR = redirection to A entry


Take changes into account

service bind9 restart



Add new hostname

This is how we had a new host-name into the network:


Update LOCAL zone

Edit local zone: 

vim /etc/bind/smartcards.local


Add a A or AAAA entry: 

my-new-host       IN      A       172.16.50.60


Update REVERSE zone

Edit local zone: 

vim /etc/bind/db.172


Add a A or AAAA entry: 

60       IN      PTR     my-new-host.smartcards.local.


Restart service

service bind9 restart




Sources

You can find a lot of information about DNS on the web. I used the following tutorials:


Bug fixes:

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