How your server can be seen from outside

Your computer at home need to connect to network of ISP before your computer can access other computers on the internet.

Your ISP will assign an unique address to identify where your computer is. ex: With this ip address, now you can use to connect to your home server from your office or anywhere in the world.

But because it is dynamically generated every time your home modem reconnect to ISP. Therefore you can not always use this ip address to access to your home server. You need to find the new ip assigned to your modem.

What is DNS

Because people hardly remember ip address, they need a meaningful name. So instead of using ip address, we use a name, a string of characters, such as,, It is much easier to remember. That is a reason why we need DNS.

DNS stands for Domain Name System. Its mission is to resolve a name to a ip. For instance: will be resolved to, will be resolved to

alt Figure 1: Domain Name System

What is Dynamic DNS

Dynamic DNS is a DNS that allow you to change ip address of hostname dynamically, and update immediately.

alt Figure 2: Dynamic DNS

Below are some Dynamic DNS providers:

Some DDNS service is already integrated with modem.

How to make your server accessible with free hostname.

  • Register an account on DDNS provider
  • Create a subdomain, such as,
  • Config your modem so that every time your modem is reset and is assigned, it automatically to update new ip address of your home modem to DDNS service.
  • So you don't need to worry about invalid ip address because of restarting your modem.

Enjoy your final outcome

Let ping your server ping []

if you have setup ssh server, you can remote access to your server via ssh