Dynamic DNS - I want the private IP address



  • I would like to be able to setup a Dynamic DNS client using my local, private WAN IP address. I know this sounds weird and I read this thread in which this request was pretty much shot down, so let me explain...

    I live in a condo building with a distributed network offering internet access both in my room and the communal rooftop. I have a pfSense server running in my room which is connected to my office VPN amoungst other things. This pfSense box sits on this condo public network with a IP address in the 10.0.0.0/21 network. If I know the IP address assigned to my pfSense WAN interface before I head up to the rooftop then I can make an OpenVPN connection straight to my room's pfSense box and connect to all my usual networks I have access to from my room.

    The problem is that occasionally the IP address assigned to the WAN of the pfSense box changes, so I'd like to be able to use a Dynamic DNS updater to read the private and not the public IP address of my WAN interface. This would of course result in a mainly usless DNS entry, but when used from within my condo building, it would allow me to connect to my pfSense box.

    Any ideas how I can override (just for one Dynamic DNS client) the default behaviour of resolving private IPs?

    PS... Yes, I know my pfSesne box is sitting behind NAT but there is literally nothing I can do about that :(


  • Rebel Alliance Global Moderator

    @mattbunce said in Dynamic DNS - I want the private IP address:

    The problem is that occasionally the IP address assigned to the WAN

    And why is that? Do you shut off your pfsense for hours/days at a time? If the pfsense wan IP is dhcp.. And its always on - it should really never change, because dhcp works via a renew method where when lease is 50% over it renews it.. Using the same IP, until such time that DHCP server will not renew it.. Or your box has been offline for so long that the lease expired and the dhcp server gave it to some other client.

    I would suggest you just leave your pfsense box on... Or for that matter just check what the wan IP is before you go up to the rooftop.. Do you really think its going to change between the time you check it and then get to the rooftop? ;)

    Can you not just check with who runs the building network and ask them to assign your pfsense box a reservation so it always gets the same IP be it off for a day or a year, etc.



  • Unfortunately, the electricity here is super unstable. I have a UPS for my pfSense box but the network itself is not UPS protected, so network restarts are common (at least a couple of times per week).

    Unfortunately nobody here at the condo building can give me a better answer than "if you are having problems with the internet, make sure you have entered the WiFi password correctly" - They were not expecting me to disconnect my in-room WAP and attach a pfSense box! The whole building runs on a UniFi system which I guess is managed remotely and nobody on-site seems to know who manages it, or who to contact.

    I have considered just picking a random IP address, but I can't be 100% sure what the DHCP range of the condo is and I'm worried that potentially their DHCP server would give out my chosen IP address. I am not sure if the DHCP server would check for current IPs in the ARP before issuing a particular address.


  • Rebel Alliance Global Moderator

    @mattbunce said in Dynamic DNS - I want the private IP address:

    I am not sure if the DHCP server would check for current IPs

    It might.. This is very common..Once you get an IP via dhcp - just make that IP static.. Worse case if/when it ever breaks change back to dhcp..


  • Rebel Alliance Developer Netgate

    RFC2136 Dynamic DNS has an option to toggle that behavior, and it's off by default. There isn't a viable way to disable that on regular Dynamic DNS at the moment.

    If your DNS host supports RFC2136/nsupdate then you could switch to that.



  • @jimp Thanks. I'll look in to this option :)


 

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