Dynamic DNS with a python script

[Marcelo de Moraes Serpa]

Thank you!

What if I would like to use my own DNS server for this (considereing I've
got my own domain names)?

On Dec 27, 2007 3:58 PM, Shane Geiger <sgeiger at ncee.net> wrote:

> Marcelo de Moraes Serpa wrote:
> > Hello list,
> >
> > I'd like to set up ssh access to my home computer so that I will be
> > able to access it from work - for this no problem, installing sshd is
> > straightforward.
> >
> > The issue here is that I don't have a fixed IP connection at home.
> > Also, I wouldn't like to use services such as no-ip or similar.
> >
> > What I thought was of writing a python program that would detect when
> > the internet network interface was restarted/started for the first
> > time and then update a DNS record at my DNS server where I would have
> > a subdomain that for my home machine's host.
> >
> > However, I have no idea on how I could detect if the network has been
> > restarted nor how I could update this DNS record. Any suggestion would
> > be greatly appreciated :)
> >
> > Thanks in advance,
> >
> > Marcelo.
>
> How to deal with networking depends on the system you use.  For Debian:
>
>    Debian uses ifupdown (see ifup(8), ifdown(8) and interfaces(5)) to
>    manipulate network interfaces. Each interface is provided with
>    several scripting hooks: pre-up, up, down, and post-down. These
>    hooks are available to each interface as in-line directives in
>    /etc/network/interfaces and also as *.d/ directories called with
>    run-parts (see run-parts(8)):
>
>       /etc/network/if-up.d/
>       /etc/network/if-pre-up.d/
>       /etc/network/if-down.d/
>       /etc/network/if-post-down.d/
>
>
>
>
> SETTING UP A DOMAIN NAME WITH DYNDNS.ORG
>
> Go to their site and set up an account.  While doing that (or perhaps
> after--I don't remember), you can choose a domain name.  You *could*
> think of what they are giving you is a subdomain--not actually a
> domain.  You will be able to choose something like foo.mine.nu where
> "foo" is the name you choose for the name of your subdomain and
> "mine.nu" is the domain they already own.  (You can choose from many
> domains they already own.)  Since they manage these domains themselves,
> they do not have to pay a registrar to set up a subdomain...and
> therefore they can give you a subdomain for free.  (Actually, I'm using
> the term "subdomain" loosely here...but I'm sure you get the point I'm
> trying to make--which is that you don't have to pay for this name.)
>
> Once you have your name (foo.mine.nu, for example), you can set up a
> program on your computer to update their DNS servers with your new
> domain name whenever it changes.
>
> --------------------------------------------------
>
>
> SETTING UP IPCHECK WITH DYNDNS.ORG
>
> I have been satisfied with my first choice (dyndns.org), so I haven't
> tried the others.  They probably work well, too.
>
> Set up an account on dyndns.org, and record the username, password, and
> domain name in your notes.  In the following examples, I use the
> following values:
>
> username:  sgeiger
> pass:  asdfasdf
> domain name:  sgeiger.mine.nu
>
>
> apt-get install ipcheck
>
> You might want to run this first so that you are in the directory cron
> will use when you run ipcheck:
> sudo su; cd ~;
>
> HERE'S HOW TO CONFIGURE IT:
> sgeiger at minime:~$ sudo /usr/sbin/ipcheck.py -l -r
> checkip.dyndns.org:8245 shanerg asdfasdf sgeiger.mine.nu
> ipcheck.py: No ipcheck.dat file found.
> ipcheck.py: Use same command+options ONCE with --makedat to create from
> DNS lookup.
> sgeiger at minime:~$ sudo /usr/sbin/ipcheck.py --makedat -l -r
> checkip.dyndns.org:8245 shanerg asdfasdf sgeiger.mine.nu
> ipcheck.py: ip1 looking up sgeiger.mine.nu
> ipcheck.py: result: 'sgeiger.mine.nu'[]['139.55.232.72']
> sgeiger at minime:~$ sudo /usr/sbin/ipcheck.py -l -r
> checkip.dyndns.org:8245 shanerg asdfasdf sgeiger.mine
> .nu
> sgeiger at minime:~$ sudo /usr/sbin/ipcheck.py -l -r
> checkip.dyndns.org:8245 shanerg asdfasdf sgeiger.mine.nu
> sgeiger at minime:~$ sudo /usr/sbin/ipcheck.py -l -r
> checkip.dyndns.org:8245 shanerg asdfasdf sgeiger.mine.nu
> sgeiger at minime:~$
>
> When you run this manually and it works you will see no output.
>
> To add a cron job to update this automatically once a day at 10 am:
>
> ###  Note:  This script should be run once a day from cron, like this
> (which runs it at 10:15 am every day)
> 15 10 * * * /usr/bin/python /usr/sbin/ipcheck.py -l -r
> checkip.dyndns.org:8245 shanerg asdfasdf sgeiger.mine.nu
>
>
> To add another names (foobar.mine.nu):
> sudo /usr/sbin/ipcheck.py --makedat -l -r checkip.dyndns.org:8245
> shanerg rQ9ll0 sgeiger.mine.nu,foobar.mine.nu
>
> ...and then put this into the cron tab:
> 15 10 * * * /usr/bin/python /usr/sbin/ipcheck.py -l -r
> checkip.dyndns.org:8245 shanerg asdfasdf sgeiger.mine.nu
>
>
>
>
> Check the mail messages on the computer you are using in case there were
> errors.
>
> Note:  This creates a file named /root/ipcheck.dat and /root/ipcheck.log
> on my computer.
>
>
>
>
> STEPS FOR ADDING ANOTHER HOST:
>  - add the host on dnydns.org
>  - run the script with makedat option
>  - run the script to update the server
>
> In the example below, ipcheck will update the dyndns.org servers for the
> names "sgeiger.mine.nu" and for "myothername.mine.nu":
>
> sgeiger at minime:/root$ sudo /usr/sbin/ipcheck.py --makedat -l -r
> checkip.dyndns.org:8245 shanerg asdfasdf
> sgeiger.mine.nu,sgeigerbot.mine.nu,myothername.mine.nu
> ipcheck.py: There is already an ipcheck.dat file existing.
> ipcheck.py: Remove this file first before running --makedat
> sgeiger at minime:/root$ sudo mv ipcheck.dat ipcheck.dat-old
> sgeiger at minime:/root$ sudo /usr/sbin/ipcheck.py --makedat -l -r
> checkip.dyndns.org:8245 shanerg asdfasdf
> sgeiger.mine.nu,sgeigerbot.mine.nu,myothername.mine.nu
> ipcheck.py: ip1 looking up sgeiger.mine.nu
> ipcheck.py: result: 'sgeiger.mine.nu'[]['139.55.233.228']
> ipcheck.py: ip2 looking up sgeigerbot.mine.nu
> ipcheck.py: result: 'sgeigerbot.mine.nu'[]['139.55.233.228']
> ipcheck.py: ip2 looking up myothername.mine.nu
> ipcheck.py: result: 'myothername.mine.nu'[]['139.55.233.228']
> sgeiger at minime:/root$
>
>
> sgeiger at minime:/nu/mine/myothername$ sudo crontab -l
> 15 10 * * *     /usr/sbin/ipcheck.py -l -r checkip.dyndns.org:8245
> shanerg asdfasdf sgeiger.mine.nu,sgeigerbot.mine.nu,myothername.mine.nu
> --acctfile /root/ipcheck.dat
> sgeiger at minime:/nu/mine/myothername$
>
>
>
>
>
>
>
> --
> Shane Geiger
> IT Director
> National Council on Economic Education
> sgeiger at ncee.net  |  402-438-8958  |  http://www.ncee.net
>
> Leading the Campaign for Economic and Financial Literacy
>
>
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