dynhost

Homemade script similar to update periodically your OVH DNS via DynHost. Mainly inspired by DynHost script given by OVH (but now offline). New version by zwindler (https://blog.zwindler.fr)

Cron

Use with cron to launch periodicaly

crontab -e
  00 * * * * /usr/local/dynhost/dynhost

Config file

You can use the sample config file given (dynhost.sample.cfg). Rename it to dynhost.cfg and change the variables to meet your own parameters. Use cron this way.

crontab -e
  00 * * * * /usr/local/dynhost/dynhost /usr/local/dynhost/dynhost.cfg

Local IP resolution method

Main resolution method is using opendns DNS service, but if for some reason, you can't use an external DNS resolver (if external DNS resolution is blocked / port 53 blocked), you can use the alternate method using ifconfig.me HTTP service.

Just add TRUE in the command line as 2nd argument

/usr/local/dynhost/dynhost /usr/local/dynhost/dynhost.cfg TRUE

A word of caution though, I switched multiple times from ifconfig.me to ifcfg.4 to ifconfig.me back again because these services tend to close/be overloaded.

DNS resolution using openDNS should be a better bet (see #1 discussion for more information)

Docker image

I'm also building an Alpine docker image that can be used to update your DynHost records. You can use the Docker image both with configuration or environment variables. I'll give you 2 examples :

Build it

For ARM (on a ARM host...)

docker build -t zwindler/dynhost:arm71 .

For amd64 (on a x86_64 node)

docker build -t zwindler/dynhost .

Docker with variables

Don't forget to change HOST, LOGIN and PASSWORD in command line

docker run --rm -e HOST=YOURDYNHOST -e LOGIN=YOURLOGIN -e PASSWORD=YOURPASSWORD zwindler/dynhost

Kubernetes as a CronJob and with configuration file

Don't forget to change HOST, LOGIN and PASSWORD in the configMap section

---
apiVersion: batch/v1beta1
kind: CronJob
metadata:
  name: dynhost-cronjob
spec:
  schedule: "00,30 * * * *"
  jobTemplate:
    spec:
      template:
        spec:
          containers:
          - name: dynhost-cronjob
            image: zwindler/dynhost
            imagePullPolicy: Always
            volumeMounts:
            - name: config
              mountPath: /usr/local/dynhost/conf.d
          restartPolicy: OnFailure
          volumes:
          - name: config
            configMap:
              name: dynhost-configmap
              cat dynhost-cm.yaml
---
apiVersion: v1
kind: ConfigMap
metadata:
  name: dynhost-configmap
  namespace: default
data:
  dynhost.cfg: |-
    HOST=YOURDYNHOST
    LOGIN=YOURLOGIN
    PASSWORD=YOURPASSWORD
    LOG_FILE=/usr/local/dynhost/dynhost.log

History

• Initial version was doing nasty grep/cut on local ppp0 interface. This coulnd't work of course in a NATed environnement like on ISP boxes on private networks.
• I also got rid of ipcheck.py dependancy thanks to mafiaman42
• I did a code cleanup and switching from /bin/sh to /bin/bash to work around a bug in Debian Jessie ("if" clause not working as expected)
• Lastly, this script uses curl to get the public IP, and then uses wget to update DynHost entry in OVH DNS
• Added a Docker version of the script for more portability (and ARM devices support)

More information

See website for more informations