Bind

Intro

Some notes how to setup a dynamic DNS...
Setup is based on Askarel's dynaname
Thank you Fred for the help!

Requirements

Your DNS server

apt-get install bind9

This will be the nameserver ns0.foo.org for our dynamic subdomain dyn.bar.org so this has to be announced in the primary DNS of your bar.org domain:

dyn    NS    ns0.foo.org.

To test it:

dig @your.primary.dns.for.bar.org dyn.bar.org
;; AUTHORITY SECTION:
dyn.bar.org.        10800    IN    NS    ns0.foo.org.

Your dynamic IP client

Old notes:

apt-get install dnsutils bind9utils
git clone https://github.com/askarel/dynaname.git

On Debian Trixie:

If not yet merged, use my branch with tsig-keygen: doegox/dynaname:phil

 apt-get install bind9-dnsutils bind9
 git clone https://github.com/doegox/dynaname
 cd dynaname
 git checkout phil

After key generation (cf below), one can remove bind9 and its dependencies

 apt remove bind9 bind9-utils dns-root-data

And we keep bind9-dnsutils for nsupdate

Setup on client

To create e.g. home.dyn.bar.org:

cd dynaname
./dynaname -G -H home.dyn.bar.org -S ns0.foo.org

Setup on server

Copy client ns0.foo.org/etc/bind/dynaname.conf to ns0.foo.org:/etc/bind/
and add a hook into ns0.foo.org:/etc/bind/named.conf:

include "/etc/bind/dynaname.conf"

For info dynaname.conf should now look like:

key home.dyn.bar.org {
        algorithm HMAC-SHA512;
        secret "some secret...";
};

zone "dyn.bar.org" in {
        type master;
        file "dyn/dyn.bar.org";
        update-policy {
                grant home.dyn.bar.org name home.dyn.bar.org A AAAA TXT;
        };
};

Create ns0.foo.org:/var/cache/bind/dyn/dyn.bar.org with the following content:

$ORIGIN .
$TTL 3600    ; 1 hour
dyn.bar.org.      IN SOA    ns0.foo.org. me.bar.org. (
                  2014060301 ; serial, increment it every time you edit file
                  600        ; refresh (10 minutes)
                  300        ; retry (5 minutes)
                  86400      ; expire (1 day)
                  300        ; minimum (5 minutes)
                  )
dyn.bar.org.      IN NS     ns0.foo.org.
$ORIGIN dyn.bar.org.

Make sure bind has RW access:

root@ns0:/var/cache/bind/dyn# ls -al
total 16
drwxrwxr-x 2 root bind 4096 Jun  3 23:44 .
drwxrwxr-x 3 root bind 4096 Jun  3 23:15 ..
-rw-r--r-- 1 bind bind  389 Jun  3 23:44 dyn.bar.org

Reload bind

service reload bind9

Check messages

tail /var/log/syslog

Setup on server with multiple clients

For several clients under the same zone dyn.bar.org, e.g. adding work.dyn.bar.org, add to dynaname.conf:

+ key work.dyn.bar.org {
+         algorithm HMAC-SHA512;
+         secret "some other secret...";
+ };
  
  zone "dyn.bar.org" in {
          type master;
          file "dyn/dyn.bar.org";
          update-policy {
                  grant home.dyn.bar.org name home.dyn.bar.org A AAAA TXT;
+                 grant work.dyn.bar.org name work.dyn.bar.org A AAAA TXT;
          };
  };

And reload bind

/etc/init.d/bind9 reload

Update from client

./dynaname -H home.dyn.bar.org -S ns0.foo.org -A 1.2.3.4

To test it:

dig @ns0.foo.org home.dyn.bar.org
;; QUESTION SECTION:
;home.dyn.bar.org.		IN	A
;; ANSWER SECTION:
home.dyn.bar.org.	300	IN	A	1.2.3.4
;; AUTHORITY SECTION:
dyn.bar.org.	3600	IN	NS	ns0.foo.org.

Update from client automatically

Using yadynip:

git clone https://github.com/twalrant/yadynip
cd yadynip
patch -p0 << 'EOF'
--- bin/yadynip     2024-11-11 17:20:40.005543486 +0100
+++ bin/yadynip     2024-11-11 17:20:59.274511702 +0100
@@ -148,6 +148,7 @@
 
 ## Perform actions with detected IP address
 for part in $(runparts $etcdir/actions.d); do
+    [ -d "$part" ] && continue
     # Get and check last known IP address for this action
     lastip=$(lastip $(basename $part))
EOF
./install.sh
rm /usr/local/etc/yadynip/checkip.d/00dir600*
rm /usr/local/etc/yadynip/checkip.d/10all-nettools
rm /usr/local/etc/yadynip/checkip.d/12showmyip
rm /usr/local/etc/yadynip/checkip.d/13whatismyip
rm /usr/local/etc/yadynip/checkip.d/20voo-netgear*
rm /usr/local/etc/yadynip/actions.d/00ipUpdate*
rm /usr/local/etc/yadynip/actions.d/00zeupdate*
rm /usr/local/etc/yadynip/actions.d/10sendmail*
mkdir -p /var/cache/yadynip/ipcaches/
ln -s /root/dynaname /usr/local/etc/yadynip/actions.d

/usr/local/etc/yadynip.conf:

verbose=none
logfile=/var/log/yadynip.log
sharedir=/var/cache/yadynip

/usr/local/etc/yadynip/actions.d/conf/d00ynaname.conf:

host=home.dyn.bar.org
ns=ns0.foo.org

/usr/local/etc/yadynip/actions.d/dynaname/: the original dynaname with key files

dynaname
home.dyn.bar.org.private

Now we can call yadynip from cron

crontab -e
*/10 * * * * /usr/local/bin/yadynip