Dynamic DNS allows you to conveniently access your SynLink PDU with an easy, memorable domain name. We will discuss these terms in depth in the following sections, followed by instructions on how to setup Dynamic DNS on your home router.
1. Basic concept of IP Addresses (i.e. Public IP vs. Local IP). Here's a short primer video on the topic of IP addresses.
2. Port Forwarding. See this previous guide for details.
3. The second half of this tutorial assumes that you have a router with built-in DDNS client. If your router does not have a DDNS client, see the section "Routers without Built-in DDNS Support" for links on how to setup a stand-alone client.
To understand the need for Dynamic DNS, we first need to review DNS and domain names.
DNS stands for Domain Name Systems. It is a system created to solve a simple problem: it is difficult to remember multiple IP addresses of your favorite websites. A DNS server accomplishes this by keeping a "directory" of domain names, where each domain name is mapped to an IP address. An example of a domain name is "synaccess.com" or "google.com".
There are many free and public DNS servers. For example, Google's DNS server is at 188.8.131.52 while Cloudflare's is at 184.108.40.206.
A DNS server's "directory" is analogous to your phone's contacts list or an address book. With an address book, you don't have to remember your friend Steve's phone number. Instead, all you have to remember is his name in order to make call.
In a similar way, a DNS let's you access a website by only using it's domain name (i.e. synaccess.com). When you type in "synaccess.com" on your web browser, your computer will ask a DNS server, "what is the IP address of synaccess.com?". The DNS server looks up "synaccess.com" in its directory and gives your browser the IP address assigned to that domain. Then, your browser proceeds to communicate with a web-server with that IP.
SynLink PDUs have a built-in web-server, meaning you can access it's web interface simply by typing in it's IP address on your web browser. This method works as long as your laptop and the PDU are in the same network.
If you need to access the PDU outside of your home network, you'll need to setup port forwarding (as discussed in this guide). Then to access the PDU, you will need to remember the public IP of your home network. Here lies the problem: not only it is difficult to remember IP addresses, your home network's IP address can change often and without notice.
Your home network's public IP address changes often. This is not an uncommon occurrence because assigning a static, non-changing public IP is expensive. The frequency in which this change happens varies among Internet Service Providers. As a result, those who want to access web services hosted within their home network will have a hard time trying to keep track of their IP, especially if changes happen every week or so.
This is where Dynamic DNS becomes useful. Rather than having to remember a set of seemingly random numbers that is your public IP address, a domain name is instead assigned to your public IP. More importantly, when your public IP changes, a Dynamic DNS client will automatically re-assign your domain name to the new IP address.
You need a Dynamic DNS service provider and a DDNS Updater Client to successfully implement DDNS.
Dynamic DNS Service Provider
Third-party DDNS services like NoIP, FreeDNS, or Dyn will provide the domain you want. Some require a small fee but most give you one domain for free.
DDNS Updater Client
This is a client software that runs inside your home network. This software is responsible for notifying the DDNS service that your public IP has changed and thus re-mapping your domain name to the new IP address.
Routers with Built-in DDNS Support
Many of today's routers make it easy to implement DDNS. Many have built-in DDNS updater client while others also provide a DDNS domain for free. I highly suggest that you use a router that have a built-in DDNS updater client because it eliminates the need of requiring another computer to host the client. The rest of this tutorial assumes that your router have a built-in DDNS client.
Routers without Built-in DDNS Support
If you're router does not support DDNS, you will need to setup a dedicated computer that is ideally always on inside your home network. If you are running a Windows system, follow this guide. For Ubuntu-based systems, follow this guide.
The following are general steps to setup DDNS on your router. The specific router you use may slightly vary but the generic instructions should still apply.
To access your SynLink PDU, simply type in your home network's domain name followed by the port where you have port forwarded the PDU's web server. The syntax is http://[domain_name]:port.
Below is an example where we've assigned a Domain Name to our Public IP address via Dynamic DNS. The Domain Name in this example is https://demo.synaccess.com:2096/login