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I am connecting to internet via a 3g dongle(that is via a local ISP). When I connect to the internet, my computer is assigned a dynamic IP. I can find this by going to whatismyip. I tried to ping my computer for that dynamic IP from another computer which is connected to internet via the same ISP. But when I pinged it I got request time out response. That means I can't exchange data between those two machines. If I have a computer with static IP which I can use to exchange data between two machines which I mentioned previously.

My question is, Is it possible to ping (in other words to exchange data) a computer which is connected to internet with dynamic IP?

Background for the question is I thought to develop a software like teamviewer. I initially thought there was no involvement in third party computer with static IP when I do a screen share with teamviewer. But with the above mentioned observation, I feel there should be a middle machine with static IP is involved (Correct me if I am wrong) at least to initiate the conversation.

If this is not possible, what is the theoretical explanation for that?

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  • i think the one of the best possible ways is to establish VPN connection between the two PC
    – Gadeliow
    Sep 14, 2015 at 12:17

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The answer to your question."Is it possible to ping (in other words to exchange data) a computer which is connected to internet with dynamic IP?" is yes, but with caveats:

  • You need to know the currently assigned IP address of the host that you are trying to ping. The dynamic IP address probably doesn't change for an extended period of time or until the host restarts.
  • Are the hosts themselves configured to respond to pings?
  • Is there some sort of firewall in between the to hosts? This could either be a physical box, or it could be something like the Windows built-in firewall. The firewall(s) could block you from pinging.
  • Is one side or the other (or both) using NAT? NAT can prevent pings from reaching the host to which you are trying to connect.
  • Since you say the hosts are both on the same ISP, does the ISP block or allow one customer to ping another customer? Some ISPs block this.

If both hosts are directly connected to the Internet with no NAT or firewall (hardware of software) in between, and you know the dynamic address of the the other host, you should be able to ping the other host. This assumes your ISP is not blocking such things. For instance, the cable ISP I use is blocking the ability to ping from one customer to another within its network.

Note: Not having a firewall protecting your company's network is a very foolish thing to do. My guess it that your company has a firewall that prevents pings from one host to another over the Internet.

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  • Really good answer, I think you can add - since lakshman is using a 3g dongle -that there is a great probability that the ISP is using a CGN. So even without NAT on customer side, the 'whatsmyipaddress' is probably shared between dozens of customers
    – Golgot
    Jul 4, 2018 at 20:43
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i think the one of the best possible ways is to establish VPN connection between the two PC . make use of this video vpn setup

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