How to Open the Nat Files

You have a desire to host a multiplayer session of your favorite game on your PC, but the steps to create it keep returning an error and other players are unable to connect. Do you know that the problem is probably the NAT set up in your router? I'll explain: to connect multiple devices to the Internet with a single subscription (and therefore a single IP address), the router uses mechanisms that allow data to be addressed to the correct recipient, distinguishing one connected device from another thanks to the combination of Private IPlistening port (or just door).

This mechanism is called NAT, or Network Address Translation, is enabled by default on all routers on the market, and it is its initial configuration that prevents other players from connecting to you. This means that, to achieve your goal, you have to manually intervene on these settings and configure the router according to your needs: in other words, you need to learn open the NAT.

How do you say? Does the single sentence already scare you? I can guarantee you that there is absolutely no need, because you have come to the right place, at a time that could not have been better: in fact, below I will explain all the procedures necessary to intervene on your router and open the doors, so as to customize the NAT according to your needs. Ready to continue? Perfect: sit in front of your desk, take a few minutes of your free time and follow my instructions carefully. I can guarantee you that, almost without realizing it, you will succeed in your intent and you will finally be able to host all the games you want!

What Does NAT Stand For

Before picking up the keyboard and working on your router, it is good to give you some hints on what you are going to change. The NAT is Network Address Translation (which you can translate into Italian with translation of network addresses), is the operation that allows the router to connect multiple devices to the Internet using a single external IP address. This result is obtained thanks to some “graphic” details that the router creates by itself, called in jargon table di routing, able to independently sort the data, both incoming and outgoing, to the various devices connected to the network (computer, smartphone, tablet, etc.): the latter are "recognized" thanks to their internal IP address.

At this point, however, it is necessary to make a clarification: in a "normal" scenario, it is the devices connected to the network that request server to receive data (mail server for emails, web server for Internet browsing, and so on); as a result, the router's NAT is configured to “let through” freely outgoing connections of the various devices, with the ability to send responses to the right device, once received.

In some particular cases, for example to host game sessions or to download at maximum bandwidth from programs such as eMule o uTorrent, it is the device connected to the router that must act as a server, and therefore it becomes essential to accept incoming connections on certain listening ports (which change from program to program): by default, this behavior is blocked in order to preserve the security of the entire network and the device. Open the NAT, or opening ports or even performing port forwarding, means just that: allowing external users to connect to your device.

Why Open Doors

Now that you know why you need to open the NAT, it's time to specify the role of the doors in all of this. As I explained earlier, the internal IP address allows the router to recognize the device to which the data must go. In your case, however, your device acts as a server and the router needs another information on the data to be delivered to it: the program to which this data must go. Because? I'll explain it to you right away.

When your device acts as a client, i.e. when you browse the Internet, consult e-mails, chat or perform other online operations, it is your program that requests data from the server on the Internet, and it is the latter that enters in the response data the identifier of the request received. In this way, the router simply has to "just" follow the routing table to correctly sort the received data. When the opposite happens, that is when you act as the server, the router must be able to forward requests from the outside, but without knowing a priori information about where the program is running: each program is identified by one or multiple ports, through which it can receive data.

These doors, in the beginning, are closed to preserve the security of your network and your devices: in order for the program to receive incoming requests, these ports must be opened inside the router, with one of the procedures that I will explain shortly. This operation, as I mentioned a few lines ago, is called port forwardingport forwarding.

Said in even simpler terms, what you will do is "communicate" to the router that, when a data destined for a certain port arrives, it must be routed to a specific device (identified by its internal IP address), opening the associated device listening port characteristic of the program. So, before proceeding further, find out which ports you need to open in the router for your game (or any other program), and what type of them is (TCP or UDP). This information is easily found in the settings of the program itself or in the guide.

Log in to the Router

In order to perform the operations I mentioned earlier, the first thing you need to do is find out the IP address of your router and get the username and password to access it. You can get the address in several ways, depending on the operating system you are using. For example, if you are on Windows, click on the button Start that you find at the bottom left and, in the search field (or in the bar at the top right of the Start Screen, for Windows 8.1), type Command Prompt, click on the icon that appears on the screen, then type the command ipconfig and press the button Submit. You can find the IP address of the router under the entry Default gateway.

For MacOSclicca sull'icona System preference you find on the Dock, then on the voice Network, select the name of the connection you are using (eg. Wi-Fi) from the left sidebar and finally click the button Advanced and then on the board TCP / IP: the IP address you are looking for is specified next to the item router.

If your operating system is Linux, click on the network icon at the top right, select the item relating to your type of connection (eg. Wi-Fi connected), then the item Network Settings, and click (I.e. corresponding to the network you are connected to.

In the new window that appears, select the tab Details: you can find the IP address of your router in correspondence with the wording Default routing. When you are done, you can exit the window by clicking on the button Cancel that you find at the top left.

If you can't access the network settings, open your operating system's program list (or App View if you are using a GNOME desktop based system) and launch the application terminal. Inside, then type the command route followed by Submit: the IP you are looking for appears under the heading Gateway.

Now, all you have to do is type the router IP so retrieved into the address bar of the browser and, where requested, enter the username and password for access: if you have never accessed the router, you can try the combinations admin / admin or admin / password. How do you say? Are they wrong? Don't worry, I have a dedicated guide for you that explains in detail how to find the default password.

If this solution does not work either, I suggest you reset the router and try to log in: to do this, press the appropriate button (which is typically located on the back) and hold it down for a few seconds, until the lights on the router go then turn on again a few moments later. This is usually a recessed button, so you may need a toothpick or other sharp object to reach it. I also remind you that if you are having trouble with the whole router login procedure, you can refer to my step-by-step tutorial to get more details.

Open the NAT

Now that you have finally managed to get into your router, you can proceed to open the ports you need. First locate the menu for the port Forwarding (Forwarding Porte, in Italian), al Port Mapping or Virtual Server, and select the item for creating a new rule (or a new one virtual server). At this stage the router offers you a creation form with several entries to fill in: you can do it by following the instructions below.

  • Server IP address (o Destination IP) - here you must enter the internal IP address of the computer on which you intend to host your game session or, in general, on which you have to open the NAT. If you don't know it, you can check out my guide on how to view IP address to find it.
  • Internal door / External door (o Initial door / Final door) - type the number of the door to open in each of these boxes. Please, the entered value must be the same for all fields.
  • Protocol (o Door type) - in this menu you must specify if the port you are interested in opening is of the TCP or UDP type (some routers also allow you to set the TCP / UDP item to accept both types of connection ids).
  • Name Rule (or simply Name) - type here the name you want to give to the forward just configured, for example Server di CS:GO.

Once all the fields have been completed, all you have to do is click on the save button (usually Save / SaveApplica/Apply) to confirm the changes and, to make sure that the settings are correctly applied, restart your router. To verify that the doors have been opened successfully, connect to this website, type in the field Port Number the number of the open door and finally presses the button Check.

Unfortunately, I can't be very detailed about the precise configuration of each router, as each manufacturer has a management panel with different items and options. To help you with the task, however, I can provide you with more precise instructions on the most popular routers in circulation.

Router TIM

If you have a router Technicolor associated with a subscription TIMclick here access control, then on the section Port Mapping and finally on the button Create new rule. After that, select from the drop-down menu Service the voice Customize, set from the menu Protocol the type of port (TCP, UDP or both), fill in the fields External start / end door Internal door with the number of the door you want to open, enter in the field Internal host the local IP address of the computer on which to open it is in the field Description a name to help you remember the service you unlocked (eg CS: GO Server).

Finally, click on ON at the switch To allow and repeat the whole procedure if you need to unlock more doors. Once you have completed your entries, click on the button OK found below to save the configuration. If you need further clarifications or have a TIM router of a different model, I invite you to consult the dedicated website for further explanations.

Fastweb Router

You have the modern router FASTGate of Fastweb? Opening the doors is very simple: once logged in, click on the item Advanced that you find at the top. Then, from the side menu, select the item Manual door configuration, click on the button Associate new port mapping and fill in the various items as follows.

  • Name - the name to assign to your rule.
  • IP address - the internal IP address of the computer on which to open the port.
  • Protocol - the type of door you intend to open.
  • External door / Internal door - fill in all four boxes with the number of the door to open.

Once the entry is complete, click on the buttons Add Save Changes. If you need instructions to configure other Fastweb routers (proprietary or compatible), I invite you to consult the instructions in the Support section of your MyFastPage.

TP-Link Router

To open NAT in routers TP-Link, click on the items Forwarding Virtual Server that you usually find on the left sidebar, then on the button Add New and fill in the form that is shown as follows.

  • Interface - leave this field as it is.
  • Internal Port (The Harbour District) e Service Port - enter the number of the door to open.
  • IP Address - enter the internal IP address of the computer on which to open the port.
  • Protocol - select the protocol of the port to open (TCP / UDP).
  • Status - set the menu to Enabled to activate the rule immediately.
  • Common service port - leave this menu unchanged, unless you want to use pre-configured settings for popular services (e.g. FTP server, e-mail server, and so on).

Click on the button Save to apply the changes made. If you need further clarification, I invite you to consult my guide on how to configure TP-Link routers.

Netgear Router

To open ports on a router Netgearclick here Advanced that you find in the management panel and, from the left sidebar, select the items Advanced Setup> Port Forwarding / Triggering. Click the button Add personalized service and, when the form appears, fill it in as shown below.

  • Service name - give a name that can help you remember the rule.
  • Initial door / Internal initial door / External door - enter the number of the door to open in all fields.
  • Internal IP address - type the local IP address of the computer on which you intend to open the port.

Fatto ciò, click on your button Apply to immediately confirm the changes made. If any steps are not clear to you, I invite you to consult my guide to configuring Netgear routers to learn more.

Router D-Link

As for routers D-Link, once you have accessed the management panel, go to the tab Advanced that you find at the top and select the item port Forwarding. Then click on the button Add and fill in the fields proposed as below.

  • WAN connections - leave this field unchanged.
  • Server Name - an arbitrary name to help you recognize the rule.
  • Schedule - with this menu you can choose when to activate the rule. Set it to Always to keep it always active.
  • Server IP address - enter the internal IP address of the computer.
  • External Port Start/EndInternal Port - fill in these fields with the number of the door to be opened, which must be the same for each of them.
  • Protocol - select the type of door to open.

Once the configuration is complete, click on the button Apply to make the rule effective. If you still have any doubts or need additional information on configuring D-Link routers, I suggest you refer to my dedicated guide.

Have you seen? Open the NAT router is not that complicated - I bet you know exactly how to proceed at this point. As I have already mentioned to you, it is essential that you know the necessary port for the correct functioning of the program you are interested in: if you have not already done so, I suggest you poke your nose through the settings to find it. You can find two such examples in my guides on how to open the doors of uTorrent and how to open the doors of eMule.