Installing ipcheck.py

Notes on how to get your Debian server serve on your ADSL connection with dynamic IP address. We suppose that your Debian server is serving HTTP on the internal LAN and that you have already your account at www.dyndns.org.

Now we must install something on our computer to tell dyndns about our dynamic ip address. It must run automatically each time when our IP address changes.

We are going to use ipcheck.py, an open-source tool written in Python. More on ipcheck.py project homepage.

• Create a directory which will serve for ipcheck's data files.

  md /mnt/snapshots/ipcheck
  cd /mnt/snapshots/ipcheck
  

• Download the script.

  wget http://ipcheck.sourceforge.net/ipcheck.py
  

• run the script a first time with the --makedat option.

  python ipcheck.py --makedat username password hostnames
  ppp0: error fetching interface information: Device not found
  ipcheck.py: No address found on interface ppp0 use -i
  

  ... oops, we must specify some device correctly...

  python ipcheck.py --makedat -i eth0 username password hostname
  ipcheck.py: ip1 looking up lsaffre.dyndns.org
  ipcheck.py: result: 'lsaffre.dyndns.org'[]['213.219.89.238']
  ipcheck.py: lsaffre.dyndns.org good 192.168.2.110 -update successful
  

  Now if we point a browser to lsaffre.dyndns.org we should get an answer.

  ... oops, we don't.

  What went wrong? ipcheck.py told dyndns.org to use 192.168.2.110 as address for lsaffre.dyndns.org. This is asterix's local ip address. This is of course wrong.

  python ipcheck.py --makedat -r checkip.dyndns.org username password 
  hostname
  ipcheck.py: ip1 looking up lsaffre.dyndns.org
  ipcheck.py: result: 'lsaffre.dyndns.org'[]'213.219.89.238']
  ipcheck.py: lsaffre.dyndns.org good 213.219.91.17 -update successful
  

• Now it works: we point a browser to lsaffre.dyndns.org

python ipcheck.py -v -l -r checkip.dyndns.org username password 
hostname
ipcheck/0.215
ipcheck.py: Fri Jul 30 19:27:05 2004
ipcheck.py: opt_router set to checkip.dyndns.org
ipcheck.py: opt_username = lsaffre
ipcheck.py: opt_password = ********
ipcheck.py: opt_hostnames = lsaffre.dyndns.org
ipcheck.py: PWD = /home/luc/ipcheck
ipcheck.py: web based ip detection for localip
ipcheck.py: Trying URL http://checkip.dyndns.org
ipcheck.py: webip.out file created
ipcheck.py: webip detected = 213.219.91.17
ipcheck.py: Good, filehosts and hostnames are the same.
ipcheck.py: Good, no ipcheck.err file.
ipcheck.py: Good, no ipcheck.wait file.
ipcheck.py: Checking hosts in file vs command line.
ipcheck.py: The database matches local address.  No hosts update.

Now we must create a cron job who will run every 5 minutes. See www.michianageeks.net/2004/cronjob.xhtml