dyndns is a HTTP based API to dynamically update DNS records (DynDNS). It’s uses Python and the Flask web framework to accomplish this task.
apt install bind9
vim /etc/bind/named.conf
zone "dyndns.example.com" {
type master;
file "/var/cache/bind/dyndns.example.com.db";
allow-update { key "dyndns.example.com."; };
};
tsig-keygen -a hmac-sha512 dyndns.example.com
vim /etc/bind/named.conf.local
key "dyndns.example.com." {
algorithm hmac-sha512;
secret "nbB5i/5pyFywRPaUpEkzxtS0she1JOuZlASceu0lLU8Pe7dYpzuVDn9vbGvof2wjGkVsSZBG2DlaM3RwPHkd9g==";
};
vim /var/cache/bind/dyndns.example.com.db
$ORIGIN dyndns.example.com.
$TTL 300 ; 5 minutes
;; NAME IN SOA MNAME RNAME
; NAME: name of the zone
; IN: zone class (usually IN for internet)
; SOA: abbreviation for Start of Authority
; MNAME: Primary master name server for this zone
; RNAME: Email address of the administrator responsible for this zone. address is encoded as a name. (john\.doe.example.com.)
@ IN SOA ns1.example.com. admin.example.com. (
1 ; SERIAL: Serial number for this zone.
3600 ; REFRESH: number of seconds after which secondary name servers should query
1000 ; RETRY: number of seconds after which secondary name servers should retry to request
3600000 ; EXPIRE: number of seconds after which secondary name servers should stop answering request
300 ; TTL: Time To Live for purposes of negative caching
)
NS ns1.example.com.
NS ns2.example.com.
A 185.11.138.33
AAAA 2a03:2900:7:96::2
systemctl enable named.service
systemctl start named.service
echo "server ns1.example.com
debug
update add debug.dyndns.example.com. 10 IN TXT \"$(date)\"
send
quit
" | nsupdate -y 'hmac-sha512:dyndns.example.com:nbB5i/5pyFywRPaUpEkzxtS0she1JOuZlASceu0lLU8Pe7dYpzuVDn9vbGvof2wjGkVsSZBG2DlaM3RwPHkd9g=='
Show all records of the zone dyndns.example.com
dig @ns1.example.com. dyndns.example.com. axfr
(axfr = Asynchronous Xfer Full Range)
Install dyndns
into the directory
/usr/local/share/python-virtualenv/dyndns
using a virtual
environment.
python3 -m venv /usr/local/share/python-virtualenv/dyndns
source /usr/local/share/python-virtualenv/dyndns/bin/activate
pip3 install dyndns
The working directory of our flask web API is in the directory
/var/www/dyndns.example.com
. Create a file
/var/www/dyndns.example.com/dyndns.ini
.
[uwsgi]
module = dyndns.wsgi:app
master = true
processes = 5
socket = /var/www/dyndns.example.com/dyndns.sock
chmod-socket = 664
uid = www-data
gid = www-data
vacuum = true
die-on-term = true
Example configuration file for nginx:
/etc/nginx/sites-available/dyndns.example.com.
server {
server_name dyndns.example.com;
listen 80;
listen [::]:80;
return 301 https://$host$request_uri;
}
server {
listen 443 ssl;
listen [::]:443 ssl;
server_name dyndns.example.com;
ssl_certificate /etc/letsencrypt/live/dyndns.example.com/fullchain.pem;
ssl_certificate_key /etc/letsencrypt/live/dyndns.example.com/privkey.pem;
location / {
include uwsgi_params;
uwsgi_pass unix:/var/www/dyndns.example.com/dyndns.sock;
}
}
vim /etc/systemd/system/dyndns.service
[Unit]
Description=uWSGI instance to serve dyndns
After=network.target
[Service]
User=www-data
Group=www-data
WorkingDirectory=/var/www/dyndns.example.com
Environment="PATH=/usr/local/share/python-virtualenv/dyndns/bin"
ExecStart=/usr/local/share/python-virtualenv/dyndns/bin/uwsgi --ini uwsgi.ini
[Install]
WantedBy=multi-user.target
systemctl enable dyndns.service
systemctl start dyndns.service
dyndns
requires a configuration file in the YAML markup language.
dyndns
looks on three places for its configuration. It picks the
first existing configuration file and ignores the later in this order:
- Custom path specified in the environment variable
dyndns_CONFIG_FILE
- Current working directory of the
dyndns
app (cwd):<cwd>/.dyndns.yml
/etc/dyndns.yml
---
secret: '12345678'
nameserver: 127.0.0.1
port: 53
zones:
- name: dyndns.example.com
tsig_key: tPyvZA==
secret
: A password-like secret string. The secret string must be at least 8 characters long and only alphanumeric characters are permitted.nameserver
: The IP address of your nameserver. Version 4 or version 6 are allowed. Use127.0.0.1
to communicate with your nameserver on the same machine.port
: The port to which the DNS server listens. If the DNS server listens to port 53 by default, the value does not need to be specified.zones
: At least one zone specified as a list.name
: The domain name of the zone, for exampledyndns.example.com
.tsig_key
: The tsig-key. Use thehmac-sha512
algorithm to generate the key:tsig-keygen -a hmac-sha512 dyndns.example.com
dyndns
offers two HTTP web APIs to update DNS records: A simple API
and a more flexible API.
The simple API uses path segments
(<your-domain>/update-by-path/secret/fqdn/ip_1
see section “Update
by path”) and the more flexible API uses query strings
(<your-domain>/update-by-query?secret=secret&fqdn=fqdn&ip_1=1.2.3.4
see section “Update by query”).
<your-domain>/update-by-path/secret/fqdn
<your-domain>/update-by-path/secret/fqdn/ip_1
<your-domain>/update-by-path/secret/fqdn/ip_1/ip_2
<your-domain>/update-by-query?secret=secret&fqdn=fqdn&ip_1=1.2.3.4
secret
: A password like secret string. The secret string has to be at least 8 characters long and only alphnumeric characters are allowed.fqdn
: The Fully-Qualified Domain Name (e. g.www.example.com
). If you specify the argumentfqdn
, you don’t have to specify the argumentszone_name
andrecord_name
.zone_name
: The zone name (e. g.example.com
). You have to specify the argumentrecord_name
.record_name
: The record name (e. g.www
). You have to specify the argumentzone_name
.ip_1
: An IP address, can be version 4 or version 6.ip_2
: A second IP address, can be version 4 or version 6. Must be a different version thanip_1
.ipv4
: A version 4 IP address.ipv6
: A version 6 IP address.ttl
: Time to live. The default value is 300.
Hit this url to delete a DNS record corresponding to the fqdn
.
Both ipv4 and ipv6 entries are deleted.
<your-domain>/delete-by-path/secret/fqdn
To update the dyndns
server you can use the corresponding shell
script dyndns-update-script.sh.
Edit the top of the shell script to fit your needs:
#! /bin/sh
VALUE_DYNDNS_DOMAIN='dyndns.example.com'
VALUE_SECRET='123'
VALUE_ZONE_NAME='sub.example.com'
This update shell script is designed to work on OpenWRT. The only dependency you have to install is curl.
Use cron jobs (crontab -e
) to periodically push updates to the
dyndns
server:
*/2 * * * * /usr/bin/dyndns-update-script.sh -S 5 -d br-lan -4 nrouter
*/2 * * * * /usr/bin/dyndns-update-script.sh -d br-lan -4 nuernberg