Update DDNS script - run at startup on Synology (part 2)

How to make DDNS update run at startup:

1_ Install PYthon via Synology package manager
2_ Take script from here (www.debian-administration.org/articles/28) and modify it to run the DDNS PY script through a SCREEN session (the following must be in the "start" session of some startup script):

    echo "Starting refresh from FTPD" >> /root/refreshlog
    /opt/bin/screen -d -m sh -c "/etc/init.d/pythonstrap"

/etc/init.d/pythonstrap being defined like this:
    /usr/bin/python /etc/init.d/refresh_DDNS_JB.py



3_ You need "screen"! For that you need to install ipkg. Follow this: http://forum.synology.com/wiki/index.php/Overview_on_modifying_the_Synology_Server,_bootstrap,_ipkg_etc#How_to_install_ipkg

4_ ipkg is not working! You need to add /opt/bin AT THE BEGINING of your PATH at following locations:
   * /root/.profile
   * /etc/profile

4_ Now finish install ipkg:
   * ipkg update
   * ipkg upgrade

5_ Install screen:
   * ipkg install screen

6_ ... Make DDNS script run at startup. I'M STUCK HERE. I copied my .sh script here (with CHMOD 0755) and there but it won't run at startup, don't know why:
   * /opt/etc/init.d/S99refreshDDNSJB.sh
   * /usr/syno/etc/rc.d/S99refreshDDNSJB.sh

So for now I run the script manually after each reboot... but what if power outage...

7_ FOUND THE REASON: in startup scripts, you must specify the full path to screen! Like: /opt/bin/screen. Yeepee!!!

8_ And: I had to put the script insite S99ftpd.sh. A standalone script won't be launched! But I'm tired to find out why.... There must be a Synology command to refresh the startup list but who cares.

Nice reference about startup scripts on Synology: http://forum.synology.com/enu/viewtopic.php?f=27&t=48260

How to fix Synology DDNS update (with No-IP)

Synology NAS are accessible from the outside using DDNS server, but their client apparently fails to update public IP changes when standing behind a NAT router (which is the common case for home usage, unless you're lucky enough to have an IPv6 ISP).

So what could I do? After not finding a solution, needing one and still loving my NAS, I wrote my own update script in Python.
To run it at startup: http://www.debian-administration.org/articles/28

Enjoy:


# Update my dynamic IP address on No-IP.org

import urllib2
import time
from datetime import datetime

URL = 'http://dynupdate.no-ip.com/nic/update?hostname=homebj.no-ip.org'
useragent = 'Synology DDNS bugfixer/1.0 your_email_noip@canazzi.com'
username = 'your_noip_username'
password = 'your_noip_password'

while 1:

    try:
        passman = urllib2.HTTPPasswordMgrWithDefaultRealm()
        passman.add_password(None, URL, username, password)
        authhandler = urllib2.HTTPBasicAuthHandler(passman)
        opener = urllib2.build_opener(authhandler)
        opener.addheaders = [('User-agent', useragent)]
        urllib2.install_opener(opener)
        pagehandle = urllib2.urlopen(URL)

        reply_good = pagehandle.read()
        pagehandle.close()

        print datetime.now(), ":", reply_good

        # every hour: update!
        time.sleep(3600)
       
    except:
        print datetime.now(), ":", "Failed to update IP! "
        time.sleep(300)

How to write your own DDNS IP update script

My brand new Synology D413j can't update it's public IP address on public DDNS sevices, like synology.om or noip.com. As it prevents remote access to it, I've started to work on the problem. 

But today I'm tired, will fix that tomorrow! For now, here are the rought steps:

1)
You'll have to create a Cront table to run periodial updates, i.e. runnung the update script: you're going to write:

DiskStation> cat /etc/crontab
#minute hour    mday    month   wday    who     command
15      23      *       *       2,5     root    /usr/syno/bin/synopkg chkupgradepkg


2) Your update script must find the current public IP. To my surprise, that's doable using standard too curl:
curl ip.alt.io

3) Finally, you must send the new address to the side. They API is HTTP-based so I just tried to go through Wget:

wget  --http-user=yean3d --http-password=heythisismypassword  --user-agent="Synology DDNS bugfixer/1.0 myniceamail@gmail.com" http://dynupdate.no-ip.com/nic/update?hostname=mynoiphostname.no-ip.org&myip=THE_IP_RETURN_BY_CURL

.... so far Wget says: "cannot write to update, access is defined". I'm tired, I'll figure out tomorrow.

NOTE: may httpget is even better and simpler?