Dynamic dns update


  • Rebel Alliance

    I do not retrieve the correct wan public IP address from the automated /etc/rc.dyndns.update.
    I have edited the cron to update every 10 mins, however the IP address being returned can be incorrect. The cached ip matches this and remains 'green'.
    I can correct it by editing the dyndns service and forcing an update, which proves the settings are valid.

    I have tested it by logging on to my dyndns account and manually changing the IP address on the service to an incorrect address, then observing the cron actions.


  • Rebel Alliance

    I believe what is happening is this:

    The Cron to update Dynamic DNS on the Router does a "checkip" and compares it to it's cached IP address.
    These addresses match and all is green and wonderful.
    However; the IP Address stored with the Dynamic DNS provider (dyndns in this case), can be different - which means you will not be able to connect.

    Performing a "Force Update" refreshes the dynDNS IP address and corrects the issue - But you need to connect to do this.

    You would not usually have this problem, unless the DynDNS address have been changed by a second service.

    Mine was changed when I set up a "spare" router with the identical config (including DynDNS name) and it changed the DynDNS IP - thus removing connectivity to the original router. The original router will not correct this error, as pointed out above..

    Any thoughts about how to correct this? Perhaps another Cron that does a "Force Update" - is that possible?



  • This is where things go wrong :
    @Gil:

    ….
    Mine was changed when I set up a "spare" router with the identical config (including DynDNS name) and it changed the DynDNS IP - thus removing connectivity to the original router. The original router will not correct this error, as pointed out above..

    When  pfSense checks the IP, it uses : see Services => Dynamic DNS => Check IP Services (normally http://checkip.dyndns.org ) and visiting http://checkip.dyndns.org  will show your IPv4 WAN.
    IF this values corresponds with the cached address, then it considers its done.
    pfSense will NOT check what has been saved at dyndns.org because when it did set the IPv4 - it cached it also. (no need to flood dyndns.org - the don't like that !). So, what has been cached was what has been stored at dyndns.org.
    If you use another router to change the IPv4 (another !) behind the back of pfSense … well ... you looked fro problems and found them  :)

    Do NOT use the "force" button to often, they can blacklist your updates.


  • Rebel Alliance

    I accept that you should not create a situation where another source will edit your Dynamic DNS IP address.

    The point is to create awareness about the consequences of doing this, and that pfSense will not correct the error - even though it periodically checks its Public IP Address.

    It is helpful to recognise why this is the case - as you point out the DynDNS service would be flooded, if not for the cached IP address solution

    I would have thought it best to discuss such issues within this forum, - we're all here to learn.


Log in to reply