What Is HTTPS Port 443 and How to Open It?

When you install an SSL certificate, one of the steps is to select port 443 – the default port for the HTTPS connection. But what exactly does it do, and what is port 443 used for? This article provides the answers and shows how to open port 443 on the most popular operating systems.

Table of Contents

1. What Is a Port and What Are Port Numbers?
2. What Is Port 443 and What Is It Used For?
3. How Does HTTPS Port 443 Work?
4. What Does HTTPS Port 443 Protect and Why Do We Need It?
5. How to Open Port 443?
6. What Are the Port 443 Vulnerabilities?

What Is a Port and What Are Port Numbers?

In simple terms, a port in networking is a software-defined number associated with a network protocol that receives or transmits communications for a specific service. Network ports ensure that connections arrive in the right place, and the traffic remains steady.

A port number identifies each transport protocol and address combination with a 16-bit unsigned integer. All network-connected devices come equipped with standardized ports that have an assigned number. 

The concept of port numbers was first introduced by the early developers of the ARPANET back in the seventies. The initial term was socket number and had a 40-bit quantity.

In total, there are 65,535 port numbers assigned to different protocols and divided into three ranges: the well-known ports, the registered ports, and the dynamic or private ports.

The well-known ports numbered from 0 through 1023 are usually reserved by large companies and popular services such as Apple QuickTime and Structured Query Language (SQL). 

To register a specific port number, you can choose from 1024 to 49,151. Dynamic or private ports range from 49,152 to 65,535 and are available to anyone. A port number can also be temporarily assigned for the request’s duration.

What Is Port 443 and What Is It Used For?

Port 443 is the universal web browsing port for all encrypted HTTPS traffic on the Internet. By default, websites use the HTTP protocol to handle all inbound and outbound information through port 80. The problem is that HTTP is not secure, and all data travels in plain text from one computer to another. SSL certificates activate the HTTPS protocol, which transfers data securely via Port 443.

When Netscape developed the original SSL protocol to encrypt and authenticate online communications between clients and servers, they chose port 443 because it was not already in use at that time.

How Does HTTPS Port 443 Work?

Today, web encryption is mandatory for all websites, regardless of size, type, or niche. If the connection between browsers and web servers is not secured, visitors can’t access the pages they want. Instead, they encounter an off-putting SSL connection warning calling them to leave the site immediately.

To encrypt a website, you need to install an SSL certificate on your server. SSL certificates are small digital files that follow the TLS (Transport Layer Security) protocol and secure data in transit between two computers over a network. The best indicator of an encrypted website is the padlock icon next to the URL.

How does encrypted data look? It’s just a random string of characters impossible to decipher by cyber criminals. The HTTPS connections are bulletproof to eavesdropping and man-in-the-middle attacks.

When users enter an HTTPS site, their web browser establishes a secure connection with the web server using the TLS  protocol. TLS encrypts data and ensures only the intended recipient can see it.

The communication between the web browser and the web server occurs through port 443, the default port for HTTPS traffic. SSL port 443 establishes a secure and encrypted connection between the web server and the web browser. Other HTTPS ports like 8443 or 2096 are also available for specific needs and connections.

What Does HTTPS Port 443 Protect and Why Do We Need It?

HTTPS port number 443 protects sensitive information transmitted between your web browser and website. Whenever you enter personal details like your credit card number, password, or any other private credentials, The HTTPS protocol keeps that info safe from being intercepted by cyber thieves, thanks to TLS encryption.

Encryption ensures that the information travels as a string of undecipherable characters that can only be deciphered by the website that receives it. Even if attackers manage to intercept the data, they won’t be able to read it.

So, whenever you see the lock icon or the “https://” in the URL bar of your web browser, you can be sure that your communication with the website is via port 443 and your information is safe.

How to Open Port 443?

Opening port 443 is typically done by configuring your firewall or router to allow incoming and outgoing traffic on that port. The specific steps for opening port 443 will depend on the type of firewall or router you are using, as well as the operating system of your computer. In this article, we provide instructions on how to open port 443 on Windows, Linux, and Mac.

Should Port 443 Be Open?

Whether or not you should open port 443 depends on your specific needs. If you want to access a website or service that uses HTTPS, port 443 should be open. Additionally, if you run a web server that uses HTTPS, you should ensure port 443 is enabled so that users can connect to your server securely.

Is Port 443 Open by Default?

Again, it depends on your firewall, router, and OS (operating system) configuration. Some platforms may have firewall port 443 open by default, while others may have it closed. It’s important to check your settings to see if port 443 is open or closed and to configure it accordingly if necessary. Most web servers use port 80 (HTTP) by default, and each server has specific instructions for opening port 443.

How to Open Port 443 in Linux?

To enable Port 443 on Linux systems, run the commands below:

1. Run the following command to allow traffic on port 80:
   sudo iptables -I INPUT -p tcp -m tcp –dport 80 -j ACCEPT
2. Run the following command to allow traffic on port 443:
   sudo iptables -I INPUT -p tcp -m tcp –dport 443 -j ACCEPT
3. Run the following command to save the iptables rules:
   sudo service iptables save

If you want to open port 443 on Ubuntu, the same instructions apply.

How to Check if Port 443 Is Open in Linux?

You can use several commands like “netstat,” “ss” or “nmap” to check whether port number 443 is open on Linux. Here’s how to do it with “netstat” command:

1. Open the terminal on your Linux machine.
2. Type: sudo netstat -tulpn | grep :443 and press Enter.
3. If the command returns any results, then port 443 is open on your system.

How to Open Port 443 in Windows?

To enable Port 443 on Windows, you need to add it to Firewall. Here’s how to allow port 443 in Windows Firewall:

1. Open the Firewall Control Panel by accessing “Start” > “Run” and typing firewall.cpl
2. On the left pane, select “Advanced Settings”, then click on “Inbound Rules” in the top-left corner.
3. Next, click on “New Rule” on the right-side panel in the “Action” column.
4. A new window will open. Select “TCP” and “Specific local ports” where you need to type “443” next to it.
5. In the “Action” window, select “Allow the connection” and click “Next”.
6. In the “Profile” window, choose “Domain” and “Private”, then click “Next”.
7. In the “Name” window, type “WCF-WF 4.0 Samples” name and click on “Finish”.

Please note, to set up the Outbound Rules, you need to repeat the septs 2 to 8.

How to Check if Port 443 Is Open in Windows With Cmd?

To check if port 443 is open in Windows with CMD, you can use the “telnet” command. Here are the steps:

1. Press the Windows key and type “Windows features” in the search bar. Then, select “Turn Windows features on or off”.
2. Tick the “Telnet Client” checkbox and click “OK”.
3. Open the Command Prompt on your Windows machine.
4. Type telnet <IP address or domain name> 443 and press Enter.
5. If the command returns “Connected to <IP address or domain name>”, then port 443 is open.

How to Open Port 443 on Macos?

Ensure your firewall is disabled (it should be by default), then follow the steps below:

1. Open the Terminal app.
2. At the prompt, enter the following command to stop the packet filler (pf) firewall in case it’s active: sudo pfctl -d
3. Open the configuration file for pf by using the nano text editor: sudo nano /etc/pf.conf
4. In the editor, add your custom rules at the bottom of the file.
5. To open port 443, enter the following command at the bottom of the file below the existing configuration: pass in inet proto tcp from any to any port 443 no state
6. Press CTRL + X to exit nano, and press Y and Enter to confirm that you want to save the file with the same name.
7. Reload the firewall’s settings: sudo pfctl -f /etc/pf.conf
8. Finally, restart the firewall: sudo pfctl -E

How to Check if Port 443 Is Open on macOS?

The instructions for checking port 443 status will vary depending on the macOS version.

On macOS 11 Big Sur or Later

1. Click the Spotlight icon in the upper-right-hand corner or press Command + Space bar.
2. Type “Terminal” in the search field and select Terminal.
3. Type: nc -zv + IP address or hostname + port number” (e.g., nc -zv www.ssldragon.com 443 or nc -zv 14.22.xxx.xxx 443) to run the telnet command and test the port status.

On Earlier macOS Versions:

1. Click the Spotlight icon in the upper-right-hand corner or press Command + Space bar.
2. Type “Network Utility“ in the search field and select Network Utility.
3. Select “Port Scan”, enter an IP address or hostname in the text field, and specify a port range. For instance, 440-443. Click “Scan”. If a TCP port is open, it will be displayed in the “Network Utility” window.

What Are the Port 443 Vulnerabilities?

Port 443 has the same exposure as the HTTPS and TLS protocols. Vulnerabilities can include the following:

• Man-in-the-middle (MITM) attacks, where a hacker intercepts the communication between the client and server to steal sensitive information.
• SSL/TLS vulnerabilities, such as the Heartbleed bug, where attackers can steal private data. This issue is specific to older SSL versions and is not present in the current TLS 1.2 and TLS 1.3 protocols.
• Malware infections, where attackers can exploit open ports to infect systems with malware.

Final Thoughts

Port 443 is an essential cog in the wheel of web security and data encryption. More than 95% of the Chrome traffic goes straight through it. Any website you visit connects to your browser over HTTPS using port 443. To learn more about HTTPS, check this definitive guide on SSL certificates.

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