Difference between revisions of "BIND"

From ArchWiki
Jump to: navigation, search
(4. Configuring slave server)
Line 226: Line 226:
  cp domain.tld.zone ${CHROOT}/var/named/sec/
  cp domain.tld.zone ${CHROOT}/var/named/sec/
Edit {{ic|/etc/named.conf}}:
Add the following to {{ic|/etc/named.conf}}:
  zone "domain.tld" IN {
  zone "domain.tld" IN {
         type slave;
         type slave;

Revision as of 14:46, 28 September 2012

Berkeley Internet Name Daemon (BIND) is the reference implementation of the Domain Name System (DNS) protocols.

BIND as caching-only server

These few steps show you how to install BIND as a caching-only server.

Install BIND

Install the bind package which can be found in the official repositories.

Edit /etc/named.conf and add this under the options section:

listen-on {; };

Adding named to boot process

Edit /etc/rc.conf (See also rc.conf):

DAEMONS=(.. named ..)

Set /etc/resolv.conf to use the local DNS server

Edit /etc/resolv.conf (See also resolv.conf):


BIND as simple DNS forwarder

If, for example you have problems with VPN connections, they can sometimes be solved by setting-up forwarding DNS server. It is set very simply with BIND. Add these lines to /etc/named.conf, and change IP address according to your setup.

listen-on {; };
forwarders {;; };

then don't forget to turn bind on, and add it to the demons array in /etc/rc.conf

Automatically listen on new interfaces without chroot and root privileges


 interface-interval <rescan-timeout-in-minutes>;

parameter into named.conf options. Then you should modify rc-script:

     stat_busy "Starting DNS"
-    [ -z "$PID" ] && /usr/sbin/named ${NAMED_ARGS}
+    setcap cap_net_bind_service=eip /usr/sbin/named
+    NAMED_ARGS=`echo ${NAMED_ARGS} | sed 's#-u [[:alnum:]]*##'`
+    [ -z "$PID" ] && sudo -u named /usr/sbin/named ${NAMED_ARGS}

So your /etc/rc.d/named should look like this:

     stat_busy "Starting DNS"
     setcap cap_net_bind_service=eip /usr/sbin/named
     NAMED_ARGS=`echo ${NAMED_ARGS} | sed 's#-u [[:alnum:]]*##'`
     [ -z "$PID" ] && sudo -u named /usr/sbin/named ${NAMED_ARGS}

Change user name in last line (with "... sudo -u named ...") if your named user is not 'named'.

Running BIND in a chrooted environment

Running in a chroot environment is not required but improves security. If you want you may implement this feature later and skip directly to configuration section (see also BIND (chroot)).

Preparing the chroot

Define the chroot directory, for example:


Create chroot directories

mkdir -m 700 -p ${CHROOT}
mkdir -p ${CHROOT}/{dev,etc,var/run/named}

To enable logging inside chroot, you also need to create a log directory:

mkdir ${CHROOT}/var/log

and inside this a file named.log as per logging statement in named.conf:

touch ${CHROOT}/var/log/named.log

You may also want to access this file from /var/log:

ln -sf ${CHROOT}/var/log/named.log /var/log

Copy necessary files

cp -v /etc/named.conf ${CHROOT}/etc/
cp -v /etc/localtime ${CHROOT}/etc/
cp -Rv /var/named ${CHROOT}/var/

As of BIND 9.8.0, you will need libgost.so to run BIND in a chroot

mkdir -p ${CHROOT}/usr/lib/engines
cp /usr/lib/engines/libgost.so ${CHROOT}/usr/lib/engines/

Create block devices

mknod ${CHROOT}/dev/zero c 1 5
mknod ${CHROOT}/dev/random c 1 8

Set permissions

chown -R named:named ${CHROOT}/var/{,run/}named
chmod 666 ${CHROOT}/dev/{random,zero}
chown root:named ${CHROOT}
chmod 0750 ${CHROOT}

If you enabled logging (see above):

chown named:named ${CHROOT}/var/log/named.log

Prepare the rc script

cp /etc/rc.d/named /etc/rc.d/named-chroot

Edit /etc/rc.d/named-chroot and simply add -t ${CHROOT} to

[ -z "$PID" ] && /usr/sbin/named ${NAMED_ARGS}

so that it looks like

[ -z "$PID" ] && /usr/sbin/named ${NAMED_ARGS} -t ${CHROOT}

Also change




Prepare variables

# vim /etc/conf.d/named

Starting named-chroot on bootup

You probably followed the first section before, so you have to add -chroot to the existing named, so that it looks like this

Edit /etc/rc.conf:

DAEMONS=(.. named-chroot ..)

Start the service

# /etc/rc.d/named-chroot start

Test the service

# host wiki.archlinux.org

Output should be something like this

Using domain server:

wiki.archlinux.org is an alias for archlinux.org.
archlinux.org has address
archlinux.org mail is handled by 10 mail.archlinux.org.

Script to regenerate the chroot environment

I use this script to (re)generate BIND chroot environment. A suitable location is /usr/local/sbin/updatebindchroot:

# Prepare or update a chroot environment for running BIND
# see http://wiki.archlinux.org/index.php/BIND

. /etc/conf.d/named

# create chroot directories
mkdir -m 700 -p ${CHROOT}
mkdir -p ${CHROOT}/{dev,etc,var/{log,run/named}}

# copy necessary files
cp /etc/named.conf ${CHROOT}/etc/
cp /etc/localtime ${CHROOT}/etc/
cp -R /var/named ${CHROOT}/var/
touch ${CHROOT}/var/log/named.log

# create block devices
mknod ${CHROOT}/dev/zero c 1 5 2>/dev/null
mknod ${CHROOT}/dev/random c 1 8 2>/dev/null

# set permissions
chown -R named:named ${CHROOT}/var/{log/named.log,{,run/}named}
chmod 666 ${CHROOT}/dev/{random,zero}
chown root:named ${CHROOT}
chmod 0750 ${CHROOT}

I call this in /etc/rc.d/named-chroot just before running named:


Now you can edit configuration in /etc/named.conf and mappings in /var/named. Then both named and named-chroot can be used (one at a time of course). Restarting named-chroot recreates the chroot applying configuration changes. You should never edit config files residing in the chroot. This should be considered essentially as read-only.

Configuring BIND to serve DNSSEC signed zones

See DNSSEC#BIND (serving_signed_DNS_zones)

A configuration template for running a domain

In our example we use "domain.tld" as our domain.

1. Preparing some folder structure

mkdir /var/named/{pri,sec}

If using chroot:

mkdir ${CHROOT}/var/named/{pri,sec}

2. Creating a zonefile

# vim /var/named/pri/domain.tld.zone
$TTL 7200
; domain.tld
@       IN      SOA     ns01.domain.tld. postmaster.domain.tld. (
                                        2007011601 ; Serial
                                        28800      ; Refresh
                                        1800       ; Retry
                                        604800     ; Expire - 1 week
                                        86400 )    ; Minimum
                IN      NS      ns01
                IN      NS      ns02
ns01            IN      A
ns02            IN      A
localhost       IN      A
@               IN      MX 10   mail
imap            IN      CNAME   mail
smtp            IN      CNAME   mail
@               IN      A
www             IN      A
mail            IN      A
@               IN      TXT     "v=spf1 mx"

$TTL defines the default time-to-live for all record types. 7200 are seconds so its 2 hours.

Serial must be incremented manually before restarting named every time you change a resource record for the zone. If you forget to do it slaves will not re-transfer the zone: they only do it if the serial is greater than that of the last time they transferred the zone.

3. Configuring master server

Copy the zonefile if using a chroot:

cp domain.tld.zone ${CHROOT}/var/named/pri/

Edit /etc/named.conf:

zone "domain.tld" IN {
        type master;
        file "pri/domain.tld.zone";
        allow-update { none; };
        notify no;

Copy to chroot:

cp named.conf ${CHROOT}/etc/

4. Configuring slave server

If using chroot:

cp domain.tld.zone ${CHROOT}/var/named/sec/

Add the following to /etc/named.conf:

zone "domain.tld" IN {
        type slave;
        file "sec/domain.tld.zone";
        masters {; };   # IP address of the master server

If using chroot:

cp named.conf ${CHROOT}/etc/

Restart the services and you are done.

See also

BIND Resources