Dynamic DNS update via ISC-DHCPD | Just my blog

/dev/random

Dynamic DNS update via ISC-DHCPD

For a long time, I had on my whishlist the dynamic updating of DNS via DHCP. The MS Windows servers usually do it out-of-the box… but I don’t want to bring a Windows-server into my private network. So after some google-work on the Internet I found this website.

All I need to do, was allow updates in the zones and tell isc-dhcpd how to do it.

So in the main settings I added the next lines (please note, I have a 172.16.3.0/24 subnet for my LAN):


ddns-update-style interim;
update-static-leases on;
key dhcpupdate
{
algorithm hmac-md5;
secret "YOURSECRETKEY";
}

zone 3.16.172.in-addr.arpa {
primary 172.16.3.250;
key dhcpupdate;
}

zone lan.example.com {
primary 172.16.3.250;
key dhcpupdate;
}


Now we also have to update the BIND-config:


key dhcpupdate
{
algorithm HMAC-MD5;
secret "YOURSECRETKEY";
};

zone "3.16.172.in-addr.arpa" {
type master;
file "master/3.16.172.in-addr.arpa-zone";
allow-update { key dhcpupdate; };
};

zone "lan.example.com" {
type master;
file "master/lan.example.com-zone";
allow-update { key dhcpupdate; };
};


Please note, that you have to make sure that the user bind is able to write/create files into the /var/named/etc/namedb/master
(chown bind /var/named/etc/namedb/master).

Now you have to restart the dhcpd and bind daemons.

Please substitute YOURSECRETKEY for your key, you can create this key with the command:

$ dnssec-keygen -a HMAC-MD5 -b 128 -n HOST dnsupdates

This command will generate two files and one with the extension .private and grep the part after the ‘Key: ‘ line.


  • Social

  • By continuing to use the site, you agree to the use of cookies. more information

    The cookie settings on this website are set to "allow cookies" to give you the best browsing experience possible and enable advertising to provide you free content. If you continue to use this website without changing your cookie settings or you click "Accept" below then you are consenting to this.

    Close