Dynamic IP a problem?? for remote access??

By techuser · 14 replies
Feb 16, 2004
  1. When I work from home I use VNC. Until yesterday my VNC was working fine....And then it said connection failed. And when I checked my IP was changed by my ISP.
    As after 5 pm everybody leaves and if IP changes when nobody is around...then I am sure I wont get connected.

    When I am trying to connect to work compuetr; Is there a way I can come to know if my Dynamic IP of work changes ...maybe if I can get an email from website(I hope thats not asking for too much...!!!)informing me of - that my IP has been changed by my ISP & that this is the new IP.

    IS there a way I can get thru this problem....
  2. RealBlackStuff

    RealBlackStuff TS Rookie Posts: 6,503

  3. acidosmosis

    acidosmosis TechSpot Chancellor Posts: 1,350

    I use No-IP http://www.no-ip.com/

    You signup for an account such as acidosmosis.no-ip.com (you can choose from a list of domains to use) then you can download a small little program that automatically updates your IP address over the Internet for you. It is in use by a lot of servers and people who aren't able to know their IP whenever it changes and need it at work, etc. I also use it so that I can VNC into my machien from work and use it.
  4. carlita

    carlita TS Rookie

    Notify you of new IP - Dynamic IP

    TellMeTheDynIP will retrieve the IP from your router and send it to your mail account(s).

    This is ideal for persons who have to connect to a computer which has a Dynamic IP. As the Dynamic IP changes every time to time, you don't know it when you want to make the connection.

  5. uerjake

    uerjake TS Rookie

    you'll want to check out my post on the other thread here. read the article on how to lock down your IP and keep your IP from switching on you.
  6. jobeard

    jobeard TS Ambassador Posts: 11,128   +982

    Nicely done!

    All users should be aware that VNC does not encrypt the channel between systems,
    so any man-in-the-middle attacker will see everything.
    (which means any system on the LAN at either end can get access to the data stream).

    I believe there are other solutions to solve that issue and (if I recall correctly)
    you can even use SSH as the link (which is encrypted) and then VNC across that

    [edit]see http://members.shaw.ca/nicholas.fong/vnc/ [/edit]
  7. LookinAround

    LookinAround Ex Tech Spotter Posts: 6,491   +184

    A comment and question re: the article
    1. I believe most (certainly many) routers provide a dynamic dns update function. Rather then installing/running the DynDNS client on your computer, check if your router can't just perform the function for you (And as one typically has multiple computers don;t need rely on one of them to be up and running for updates to occur)
    2. If you want assign your pc a static IP on your LAN, isn’t it best to do it through the router?
      a. Either have the router assign you a static IP you tell it
      b. Check/conig your router to use a limited IP range for its dynamic assignments. Then one be sure to choose a static IP outside of this range to be sure never of any conflicts
  8. jobeard

    jobeard TS Ambassador Posts: 11,128   +982

    addresses on your LAN can easily be static, but you need to avoid DHCP making an assignment
    on that address *IF* that system is not presently running.
    (1) place the address and the higher end if the LAN subnet
    (2) use MAC address mapping to coerce ALL systems to 'known' addresses which ACTs like static but is not.

    I use (2) to ensure all my systems are always -thru-0.9 so that
    I can allow guests to use my connection AND control sharing only to my systems :)

    DynDNS is a means to understand the PUBLIC address assigned to your modem/router
    so that the system at work has a constant target to which it can connect.
    This is just a faked-up variation of DNS so the access is by name and the
    IP address change doesn't matter.

    No router can alter the public side of the interface -- it can accept RIP calls to change the ISP DNS address, however.
  9. LookinAround

    LookinAround Ex Tech Spotter Posts: 6,491   +184

    i'm talking about the same function as performed by DynDNS udpate client the article instructs users install. it detects when the user's public IP (which is assigned to hostname) changes so DNS servers will also be updated for the new IP address.

    This same function can be found in many home routers

    /******* EDIT ******/
    should add: found in many home routers making unnecessary (if not inconvenient) to have to be sure it's running on a computer that's always up in order for public IP changes to be reflected by hostname lookups
  10. jobeard

    jobeard TS Ambassador Posts: 11,128   +982

    Here's the problem I see;

    Something external to the router can track the old vs new ip and then change the
    logical name. If a Release/Renew cycle takes place WHILE the router is running, then
    *maybe* it can tell and respond, but can not change the logical name.
    DnyDNS.org can hold the logical name and easily remap the new ip to it.

    If the router is running, then powered off for a while, and then brought online again,
    it has no means to tell that the ip is new or a duplicate of that last seen. Again,
    the router is unaware of the logical name at all times.
  11. LookinAround

    LookinAround Ex Tech Spotter Posts: 6,491   +184


    I see the problem you speak... but is not the function talking about and in DynDNS client mentioned in article or by routers (which i suggest using to replace the function)

    They only look for a change of public IP address. The hostname never changes. Is only a matter of DNS servers update the IP address they return on a hostname lookup.

    /************* EDIT *****************/
    should add that the router (just like the DynDNS client) both require your user and password for your DynDNS account to logon and affect the change.
  12. jobeard

    jobeard TS Ambassador Posts: 11,128   +982

    the change invoked by DnyDNS is to THEIR dns servers, not the ISP dns server.

    I haven't seen your assertion work AND it can only be tested from internet side
    of the router which your believe supports this function.

    I would really like to see a demonstration --- sorry, Doubting Thomas here.

    As I don't need this to work, my comments are purely academic so judge for yourself the effectiveness of ANY solution :) {like always}
  13. LookinAround

    LookinAround Ex Tech Spotter Posts: 6,491   +184

    I think when i said "The router provides the same function as the DynDNS update client" you're thinking "with no configuration"

    The router implementation requires most the same parameters as DynDNS update client. I've been successfully using router implementations (vs running the software client) for a couple years

    Here's a snapshot from a netgear manual to clear up details :)
  14. uerjake

    uerjake TS Rookie

    well, it was just a starting point, anyway. :) sorry!
  15. LookinAround

    LookinAround Ex Tech Spotter Posts: 6,491   +184

    Sorry? No, need sorry at all

    It was a helpful article! :grinthumb

    And just a couple minor tweaks/clarifications as points-of-discussion are good to bring out in the forum as well.
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