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What is a public IP address, how to know if you have one and its advantages

Qué es una dirección IP pública, cómo saber si tienes una y sus ventajas

This is a topic of general interest, because we all have an internet service at home. If you use it to watch Netflix, YouTube, social media, download music and movies, you’re probably happy with your current internet provider. By ISP I mean «Internet Service Provider» or simply the company that provides you with Internet services. However, if you have a Play Station at home, play online on your computer, have surveillance cameras, or plan to install them in the near future, you may not be fully satisfied with your current ISP. Residential internet plans are not normally prepared to handle some of these situations optimally, and this is usually because these plans have a private IP address, which has Internet restrictions, which is not the case. in the case of a public IP and which is usually delivered in corporate Internet plans.

What is a public IP

An IP address is a set of numbers that identifies a computer or device on a network. Specifically, it is the logical or «virtual» identifier of that computer’s network card. A public IP address is the identifier of a computer at the Internet level. That is, it can be seen and located on the Internet. By deduction, a private IP is not visible on the Internet, but only in a certain private network, and therefore has Internet connection limits.

Public IP vs. Private IP at the ISP level

In the case of Internet service providers, they may provide Internet services to their subscribers by assigning them a public IP or a private IP. The most common is currently the second case to reduce costs and due to the limitation of public IP addresses. In any case, regardless of the type of IP, it will be associated with the subscriber’s router.

Because a public IP can be viewed or located on the Internet, it has direct contact or free communication with any online equipment or service. Because there are no intermediaries involved, there are no Internet connection issues. It’s Te is not the case for a private IP, which, although it provides a subscriber with access to the Internet and will generally not have problems for normal use, there are cases where it will be a problem.


This is where the problem of ports comes into play. When two computers establish a connection, suppose that the subscriber’s router (or a device on your network that will communicate to or from that router) and an Internet server do so through communication channels called ports. These ports must be open or free so that there are no connection problems. HowWhen an ISP assigns a private IP to the subscriber, that IP is assigned by a server that has control over that connection and becomes a wall or barrier between the subscriber and the Internet. This is what is known as strict NAT or CG NAT.

If the ports on the ISP server are blocked, there is a firewall, filter, or restriction for free connection, which usually happens, even if you open the ports on the router, you will have problems with the services, especially access remote (how to access surveillance cameras), P2P applications such as download managers or video games. Internet service providers do this to protect against external attacks on their network and computers, as well as on their customers, but it has these disadvantages.

How to know if I have a public IP

To find out if you have a public IP, you need to check the IP address that appears in the WAN information on your router or internet service modem. Public IPs can range from 1 to 191 in the first byte (except for IPs starting at 10.0.0 and 172.16.0). Here are some examples of public IP addresses:


The first byte of all these IP addresses, 98, 157 and 172, falls within the indicated range, so they are public IP addresses. The last IP address would be the exception if it started with 172.16.0, but since its first three bytes are 172.67,138, It’s not necessary.

Another way to find out if your IP is public is to check if the IP displayed in your computer’s WAN information matches the IP address that appears in speed counters, such as, or in «What’s my IP» pages, many of which are on Google. If these IP addresses are different, then you have a private IP.

How to have a public IP

The conventional thing is to request it from your ISP. Some may assign it to your home or internet plan at home for an additional monthly amount, which in Ecuador is usually $ 5 or up to $ 10 in some cases. . This is the most cost-effective way, but not all ISPs offer you this benefit. With the shortage of IPv4 addresses, it is becoming more and more common to purchase a corporate or business internet plan that includes or should include a public IP in your monthly fee. Unfortunately, these types of plans usually cost twice or three times more than an internal plan.

Another way to get a public IP is by hiring a VPN service, such as NordVPN, which offers dedicated or static public IPs for $ 70 per year. If you set up this VPN on your router, you can have remote access to your internal network from anywhere in the world, for example to access security cameras.

In addition, this GitHub page explains how to remove free NAT or CGNAT double performed by your ISP, which is one of the things you are looking for with a public IP. I tried to do what is explained there, but it was too technical for me, so I leave it here.

Public IP and closed ports

Despite the fact that you have a public IP, your ports are likely to appear closed, and if you have already opened them correctly in the router, as I explained here, it only remains to deduce that the ISP has blocked the ports because in ultimately they are the ones who control the connection. It is illogical for an ISP to do this, especially if you pay a monthly fee for a public IP or a corporate plan with this type of IP. In this case, you’ll need to resolve the issue with your provider or change your ISP.

I have two public IPs!

You need to make sure that the public IP assigned to you is a Real public IP or «traceable» on the Internet. That is, you need to check if the IP that appears in the WAN information on your router or modem is the same that appears on the Internet, for example, when you look at pages like «what is my IP» or speedometers, such as speedtest. net. Some Internet service providers offer Public «fictitious» IP addressesThat is, a public IP appears on your router, but on the Internet it appears with a different public IP, the latter over which you have no control. Namely, both IP addresses are public but different. This prevents the operation of open ports or DMZs, for example. I can’t tell if they do this on purpose or if they have a logic problem on their computers. However, this means that you may still be behind a router or server and have no direct contact with the internet. You can access your router from anywhere with the IP displayed on the WAN, but this is the only advantage you will have with this type of «False» public IPs.

How to open ports on a router or modem (DMZ, UPnP, public IP)

Changing Internet service providers: 3 internet service providers reviewed and how to choose the best one

What is double NAT (strict or NAT 3) and how to remove it