Setting Up DYNAMIC DNS and DHCP
ON OPENBSD5.1
The purpose here is to create a DNS + DHCP
machine where the DNS is Automatically updated according to the IP allocated by
the DHCP.
For the following purpose first we have to
install the ISC-DHCP and remove the default shipped DHCP, as it does not have the feature to
implement the Automatic DNS updation.
Package
adding
Now replacing the executable
Run the following commands
#cd /sbin
#mkdir isc-dhcp-2.0
#mv dhclient isc-dhcp-2.0/
#mv dhclient-script isc-dhcp-2.0/
#mv /usr/local/sbin/dhclient-script
dhclient-script
#mv /usr/local/sbin/dhclient dhclient
#cd /usr/sbin
#mkdir isc-dhcp-2.0
#mv dhcpd isc-dhcp-2.0/
#mv /usr/local/sbin/dhcpd dhcpd
#mv dhcrelay isc-dhcp-2.0/
#mv /usr/local/sbin/dhcrelay dhcrelay
#cd /usr/bin
#mv /usr/local/bin/omshell omshell
#cd /etc
#mkdir isc-dhcp-2.0
#mv dhclient.conf isc-dhcp-2.0/
#mv dhcpd.conf isc-dhcp-2.0/
#cp
/usr/local/share/examples/isc-dhcp/dhclient.conf dhclient.conf
#cp
/usr/local/share/examples/isc-dhcp/dhcpd.conf dhcpd.conf
Note:- If some some the above commands gives
error like “no such file” or similar don’t panic just follow and complete the process and if encountered
any error, visit logs J.
Now generating the Key and copying it to
/var/named/etc/rndc.key
#rndc-confgen
#less /etc/rndc.key
key
"rndc-key" {
algorithm hmac-md5;
secret
"4XS+kgobLMI3WmmLWgmMsQ==";
};
Copy the above key and then run
#cp /etc/rndc.key /var/named/etc/rndc.key
Configuring
the dhcpd.conf
/etc/dhcpd.conf
####################START####################################
authoritative;
# No other DHCP servers on this subnet
ddns-update-style interim;
#Supported update method - see man
using ddns
ignore client-updates;
# Overwrite client configured FQHNs
ddns-domainname "example.com.";
ddns-rev-domainname "in-addr.arpa.";
allow unknown-clients;
###This is the key which we copied earlier, pasted here.
key "rndc-key" {
algorithm hmac-md5;
secret
"4XS+kgobLMI3WmmLWgmMsQ==";
};
zone example.com. {
# Forward zone to be updated
primary 127.0.0.1;
key rndc-key;
}
zone 8.168.192.in-addr.arpa. { # Backward zone to be updated
primary 127.0.0.1;
key rndc-key;
}
option subnet-mask 255.255.255.0;
default-lease-time 172800;
max-lease-time 1209600;
shared-network example {
subnet 192.168.8.0 netmask 255.255.255.0 {
range 192.168.8.40 192.168.8.250;
option subnet-mask 255.255.255.0;
option broadcast-address 192.168.8.255;
option routers 192.168.8.1;
option domain-name "example.com";
option domain-name-servers 192.168.8.1;
}
}
#############################END##############################
Here the DHCP is configured for only single
subnet hence one can increase the number of networks he/she wants to use
according to his/her choice
Setting up DNS Server
The following “named.conf” consist only the two zone files which has to be
updated according to the DHCP allotment, one can also have many other zone
files which are static not to be updated dynamically and has different domain
names according to his/her suitability.
Putting the following to the /var/named/etc/named.conf
========================START=================================
// $OpenBSD: named-simple.conf,v 1.10 2009/11/02 21:12:56 jakob
Exp $
//
// Example file for a simple named configuration, processing both
// recursive and authoritative queries using one cache.
// Update this list to include only the networks for which you
want
// to execute recursive queries. The default setting allows all
hosts
// on any IPv4 networks for which the system has an interface,
and
// the IPv6 localhost address.
//
acl clients {
localnets;
::1;
};
options {
version ""; // remove this to allow version queries
listen-on { any; };
listen-on-v6 { any; };
empty-zones-enable
yes;
allow-recursion {
clients; };
};
logging {
category lame-servers
{ null; };
};
// Standard zones
//
zone "." {
type hint;
file
"etc/root.hint";
};
zone "localhost" {
type master;
file
"standard/localhost";
allow-transfer {
localhost; };
};
zone "127.in-addr.arpa" {
type master;
file
"standard/loopback";
allow-transfer {
localhost; };
};
zone
"1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa"
{
type master;
file
"standard/loopback6.arpa";
allow-transfer {
localhost; };
};
###This is the key which we copied earlier also pasted here
key "rndc-key" {
algorithm
hmac-md5;
secret
"4XS+kgobLMI3WmmLWgmMsQ==";
};
zone " example.com" IN {
type master;
file "master/ example.com.zone";
notify yes;
allow-update { key "rndc-key";};
};
zone "8.168.192.in-addr.arpa" IN {
type master;
file "master/8.168.192.zone";
notify yes;
allow-update { key
"rndc-key"; };
};
================================END============================
the following in /var/named/master/example.com.zone
========================START=================================
$ORIGIN .
$TTL 86400 ; 1 day
example.com IN SOA example.com. root. example.com. (
2013034708 ; serial
10800 ; refresh (3 hours)
3600 ; retry (1 hour)
604800 ; expire (1 week)
86400 ; minimum (1 day)
)
NS ns1.example.com.
$ORIGIN example.com.
$TTL 3600 ; 1 hour
================================END============================
the following in /var/named/master/8.168.192.zone
========================START=================================
ORIGIN .
$TTL 86400 ; 1 day
8.168.192.in-addr.arpa IN
SOA example.com. root.example.com. (
2013032774
; serial
10800 ; refresh (3 hours)
3600 ; retry (1 hour)
604800 ; expire (1 week)
86400 ; minimum (1 day)
)
NS ns1.example.com.
$ORIGIN 8.168.192.in-addr.arpa.
$TTL 3600 ; 1 hour
================================END============================
In the last changing the
ownership of NAMED directory
#chown –R named:named /var/named/
And making dhcpd and named run on start up
Open /etc/rc.conf and search
dhcpd_flags=NO
to
dhcpd_flags=""
and
named_flags=NO
to
named_flags=""
