View source for DDNS

When a server is behind a firewall I want to know when the server's public IP address changes, and
to communicate it back to my DNS servers at dns.he.net.

I need to know the outside IP address, not the private IP address of the server itself.

== DDNS on Debian servers ==

'''HE.net part: Create a key.''' You have to create a key on the DNS server so that
it will trust updates coming from the Debian server.

# Log into dns.he.net
# Go to the appropriate domain
# Click on the entry for the server (create one if it does not exist)
# Check the box "Enable entry for dynamic DNS. This will also clear the current IP address and set TTL to 5 minutes.
# Click Update.
# There will now be a "recycle" type icon for the entry. Click on it to either enter a key or generate a random key.

'''Debian part: Install and configure a DDNS package.'''

# sudo apt-get install ddclient

=== /etc/ddclient.conf ===

<pre>
# /etc/ddclient.conf

protocol=dyndns2
use=cmd

# Read ip address from Mikrotik
cmd=/usr/local/sbin/get_ip.py

server=dyn.dns.he.net
login=bellman.wildsong.biz
password='eOYop3nMoEaT4a4U'

daemon=3600                 # check every hour
syslog=yes                  # log update msgs to syslog
mail=root                   # mail all msgs to root
mail-failure=root           # mail failed update msgs to root
pid=/var/run/ddclient.pid   # record PID in file.

bellman.wildsong.biz
</pre>

=== Getting the outside IP address ===

/usr/local/sbin/get_ip.py contains

<pre>
#!/usr/bin/env python
#
#   Read our outside IP address from the Mikrotik router.
#
import sys,subprocess
import re
args = ['ssh', 'bwilson@192.168.1.1', '/ip address print']
re_ip = re.compile(r'^ 1 D ([\d\.]+)')
p = subprocess.check_output(args)
for line in p.split('\n'):
    mo = re_ip.search(line)
    if mo:
        print mo.group(1)
        exit(0)
exit(-1)
</pre>

== Mikrotik "/IP/Cloud" Service ==

This uses DDNS to talk to a service hosted by Mikrotik, we don't need it right now.


[[Category: Network]]
[[Category: System Administration]]