This repository is no longer maintained and read-only.
This is a little tool which helps keeping DDNS records up to date. This is not to be confused with the well known Dynamic DNS services like dyn.com or others.
Furthermore this tool is used with DDNS capable DNS servers. However the mechanics are the same. A daemon is started which check periodically for a change of the external IP, usually by pulling some webpage which returns the IP address of the requesting client. Then this IP address is checked against a DNS A record and if required an update is attempted on that record.
The software is expected to build on RHEL7 and it's derivates. It requires the EPEL repository for the perl-Config-IniFiles dependency. For installation download the release tar and execute the following statement:
rpmbuild -ta ddnsd-*.tar.gz
Of course this requires you to have setup a proper rpmbuild environment. After execution of the above command a rpm file will be dropped in the appropriate place which then can be installed on the target system.
For distributions other than RHEL7 the installation is left to the user. However I'm happy to accept merge requests for deb packaging or others.
On the system which should report it's IP address generate the DDNS keypair
using the following command, replacing host.domain.foo with the actual
FQDN of the system.
dnssec-keygen -a HMAC-MD5 -b 512 -r /dev/random -n HOST host.domain.foo
This will create two files:
- Khost.domain.foo.*.key: this file contains a DNS record for insertion in the DNS zone - we will not need that for this scenario
- Khost.domain.foo.*.private: this file contains all key specific data and also the key itself which we are interested in
Use the following command to extract get the key:
cat Khost.domain.foo.*.private | grep Key: | cut -f2 -d' '
wyTGnDpoL6RxdppJWM/+wt8vi375z1Fjd/nyKI13CZixecJUfH2yenne1RILxoemPlb3C82mxCWUjvBhbxjvlg==
On the DNS server updating the record must be allowed. This is done by adding to additional blocks to the configuration (named.conf):
key host.domain.foo. {
algorithm HMAC-MD5;
secret "wyTGnDpoL6RxdppJWM/+wt8vi375z1Fjd/nyKI13CZixecJUfH2yenne1RILxoemPlb3C82mxCWUjvBhbxjvlg==";
};
zone "domain.foo" IN {
type master;
file "data/domain.foo.zone";
update-policy {
grant host.domain.foo. name host.domain.foo. ANY;
};
};
The ddnsd side needs a configuration like the following to work (ddnsd.conf):
[host.domain.foo]
keysecret = wyTGnDpoL6RxdppJWM/+wt8vi375z1Fjd/nyKI13CZixecJUfH2yenne1RILxoemPlb3C82mxCWUjvBhbxjvlg==
For a reference checkout the man page.
ddnsd is integrated with systemd and NetworkManager. You can use the usual systemctl commands to start, stop, enable or disable ddnsd. If ddnsd is enabled and NetworkManager detects an change on the interface running the default gateway it will also restart ddnsd automatically (useful for ppp or other dhcp based environments).