Dynamic DNS

Discussion in 'General' started by adamjedgar, Sep 24, 2017.

  1. adamjedgar

    adamjedgar Member

    Not sure if this has been discussed...i am on my mobile phone writing this.

    What are the advantages/disadvantages of setting a static internal ip, port forwarding through NAT, and using dynamic dns to resolve dhcp external ip address on a webserver?

    Also, would it work for other services on the same server...like email?
    Would it adversely influence individual client domains/services hosted in a shared environment?
  2. ztk.me

    ztk.me ISPConfig Developer ISPConfig Developer

    not entirely sure what you're asking
    except some telcos block mailing ports so you wouldn't be able to send mail,
    some telcos do share IPv4 so you and a lot of other clients have the same IP but different port-ranges available
    remote mail-servers would likely identify dynamic-ips from ISPs as spam or block those ranges entirely

    besides from avail bandwith and the above ( oh yeah, + power consumption, no service while using the vacuum ... ^^ ) there is no reason why it can't be done ;)

    or did you mean using like virtual machines on a server with limited IPs and using internal NAT with PF to different machines? no issue with that, it's just another hop in between but perfectly fine.
  3. adamjedgar

    adamjedgar Member

    yes virtual machines with dynamic dns. My reason for asking this originally was because google cloud was changing my hosts file re-adding its own entry for hostname with its own internal ip address (which is dynamically assigned).
    I have since found out a way of forcing the server to prevent changes to hosts file by running chattr +i /etc/hosts. I am not sure if this is likely to cause any issues or not?
  4. ztk.me

    ztk.me ISPConfig Developer ISPConfig Developer

    ok, that does explain a few things, I once looked at this cloud feature and was kinda confused in the beginning what the heck they are doing there ^^ since then, never touched it again ...
    So I'm not entirely sure, but if they don't check wether that file has been rewritten and you can reach all services you need to and everything works, I'd totally do that aswell ;)

    For ISPconfig it shouldn't be any issue at all, however it shouldn't be an issue whatever google sets that file to, you just need to act as beeing behind a firewall and configure service respectively when I remember right.

    Maybe I'm missing something?
  5. adamjedgar

    adamjedgar Member

    My google cloud trial ends in january. Once that is done, i can assign more than one static ip address (internal and external). Dynamic dns wont be an issue then i suspect.
  6. ztk.me

    ztk.me ISPConfig Developer ISPConfig Developer

    well then, you can write a great story/howto for sure I assume ;)
  7. sjau

    sjau Local Meanie Moderator

    well, lots of mailservers won't accept incoming mail from another mailserver on a dynamic ip...
  8. ahrasis

    ahrasis Well-Known Member HowtoForge Supporter

    ISPs normally block port 25 on dynamic ip (like mine) and this is the reason why it won't work most of the time. The only work around for me to send emails is using a relay. This said, I am not sure how Google Cloud works though. If you mean an internal ip (not external) is assigned using dhcp like a router does, then perfect server tutorials already deal with it by fixing ip for your server. To be sure, do ask Google Cloud service about it.

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