Can I use DynDNS for just my workstation on a campus network?

Pedro Parkero June 11, 2011
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I want to set up a virtual server for my academic organization, so I can deploy a database system accessible from the web. I’m a part of a public network with around a hundred users. The network admin has agreed to help me out.

As I understand it, DynDNS’ service can give me 2 domains that link to my computer for free, but we have to configure our router to use DynDNS. Would that affect the other users in the network when I’m the only one who needs the service?

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  1. Mike
    June 11, 2011 at 4:57 pm

    In general, no, it shouldn't effect your network at all. 

    DynDNS doesn't link to your computer in particular but a public IP Address which you set it to resolve to ~ in your example the public IP of the Router/Modem of the entire network. It is the Routers job to forward particular request to your machine.

    Now, this is the point where it can get difficult. 
    If your academic organization has only one public IP Address and is running ~let's say a public web server on it, you cannot forward Port 80 to your machine anymore. Because then all requests to this port on this public IP (doesn't matter if people are using the DynDNS name or any other domain pointing to this IP) will land on your machine instead of the original web server.

    Anyways, working together with the network admin I'm sure this is nothing you yourself have to wrap your head around ~ the network administrator should know about the limitations.

    • Pedro Parkero
      June 11, 2011 at 5:05 pm

      Okay, do you mean to say that if my organization is already running a web server then I can't set up another web server? Good thing, because my organization doesn't have a web server yet and I plan my workstation to be the one & only web server.

      • Mike
        June 12, 2011 at 8:17 am

        Yes and no.

        Let's say you got one public IP Address and two domains:
        IP 200.200.200.200, domains "example.com" and "example.dyndns.com"
        The Router doesn't care about DNS names ~ in general it only sees IP's and Ports and route requests and traffic according to it's rules.There are very few Routers which are able to route based on host names but it's always good assumption that it cannot.So no matter if you access http://example.com or http://example.dyndns.org both of them will be a request to 200.200.200.200:80 (IP and the Port for http).
        This is the same request in both cases therefor the Router will forward it using the same rule to the same machine.

        If you access http://example.com and https://example.dyndns.com it's not the same. The first one will be a request to 200.200.200.200:80 while the second one using HTTP SSL will bee 200.200.200.200:443 (IP and Port for https)

        These are two different requests and can be forwarded using different rules to different internal machines.

        Having multiple public IP's e.g. 200.200.200.200 and 222.222.222.222 this is easy. You could point one domain example.com to200.200.200.200 and example.dyndns.com to 222.222.222.222.
        Then you tell your Router to forward 200.200.200.200 to one internal machine e.g. 10.0.0.200 and requests to 222.222.222.222 to 10.0.0.222.
        Like the single IP example you can further distinct it by using port based rules. 

        There is another way to run multiple webservers behind a single Public IP which uses VirtualHosts to forward or redirect requests based on host names, Apache Reverse proxy and whatever other option is available but this goes beyond my memory and I don't think at this point it's necessary to Google it up and add to the post.

        It's something your network administrator has to wrap his head around when they decide to run their own webserver :-)

        • Pedro Parkero
          June 16, 2011 at 4:13 pm

          Thanks for a very informative reply Mike! With your suggestion, I might just create links with different port requests so my community can access different services in my workstation (e.g., like this link: https://example.dyndns.com:8080 right?) Again, I thank you for your input. I can now proceed because of this.

        • Pedro Parkero
          June 17, 2011 at 2:33 am

          I was confused because I thought that DynDNS will also handle the IP Addresses of the other computers connected to my network and it will handle all outgoing requests. So now I realize that the service will only handle the forwarding of incoming requests to my configured server.