Tuesday, July 24, 2012

Amazon ec2 dynamic ip updater

How to setup ddclient on Centos machine running in Amazon EC2 to update it's public ip address to dyndns-like services.

1. Install ddclient from EPEL repository
$ sudo yum install ddclient
2. modify/add following lines in /etc/ddclient.conf:

use=cmd, cmd='curl'

Some explanation on "use" line: this is the recommended way to get the public ip address of the running machine.

3. Start ddclient service:
$ sudo /etc/init.d/ddclient start

4. Do not forget to set ddclient's default runlevels to start after reboot
$ sudo chkconfig ddclient on

That's all.

It seems that dynupdate.no-ip.com does not accept SSL traffic other than TLSv1.
T workaround this put following line to /usr/sbin/ddclient after 1864th line:
            SSL_version => 'TLSv1',

The diff between orig and new file will lokk like this:

# diff -u ddclient.orig ddclient
--- ddclient.orig       2012-10-27 10:06:10.000000000 +0200
+++ ddclient    2012-10-27 09:49:56.000000000 +0200
@@ -1861,6 +1861,7 @@
             Proto => 'tcp',
             MultiHomed => 1,
             Timeout => opt('timeout'),
+            SSL_version => 'TLSv1',
            defined $sd or warning("cannot connect to $peer:$port socket: $@ " . IO::Socket::SSL::errstr());
     } else {

Do not forget to re-apply this patch after updating ddclient!

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