Port 445 Explained: Sharing Files on Your Windows Network

Ever open a folder on another computer on your network? Maybe to grab a document you forgot to save on your own machine? That handy feature relies on something called a port, and on your network, port 445 is the key player for Windows machines.

Moreover, imagine your computer is a house, and ports are like special doors. Each door lets a specific type of visitor in. In this case, Port 445 is like the door for sharing files and printers with other computers on your network.

However, its importance also makes it a target for cyber threats, particularly ransomware attacks. As a result, this is why a nuanced grasp of Port 445’s functions and vulnerabilities is essential for any IT professional.

In this blog, we’ll explain what port 445 does, how it helps you share things, and even some tips to keep your files safe.

What is Port 445 or TCP Port 445 ?

Port 445, also known as TCP (Transmission Control Protocol) port 445, is one such port that stands out due to its significant role in networked computers running Windows networking.

This port is crucial for file sharing and network communication, especially in the latest versions of Windows, though it also has its roots in earlier versions of the operating system and is integral to network ports and network connections.

Specifically, it is commonly associated with the Server Message Block (SMB) protocol and the Common Internet File System (CIFS).

Port 445 facilitates the seamless sharing of files, printers, and other resources across a network. This functionality is essential for visuality systems and the smooth operation of networked environments.

Furthermore, TCP port 445 is a specific pathway on your computer dedicated to a helpful function: sharing files and printers on a Windows network. Let’s break it down:

  • TCP (Transmission Control Protocol): Imagine TCP as a reliable delivery service for data on your network. In other words, it makes sure information gets sent and received correctly, like a package with a tracking number.
  • Port 445: This is the designated address for file and printer sharing on Windows machines. Think of it as a special door labeled “File Sharing” on your computer.

As a result, Port 445 makes collaborating on documents and using printers on a network much easier. It’s like having a central location to access shared resources without physically moving things around.

Moreover, as we delve deeper into the world of Port 445, we’ll explore its uses, the evolution of the SMB protocol, and best practices for securing this critical aspect of your network infrastructure.  

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How does Port 445 work ?

Imagine you’re living in a giant apartment complex. To share things with your neighbors, you might leave a recipe on a bulletin board in the hallway, or lend them a cup of sugar through your door.

Similarly, on a computer network, ports function similarly, acting as designated pathways for specific types of information to travel.

In this case, Port 445 is like a special door for Windows machines, specifically designed for sharing resources like files and printers with other Windows computers on the network.

Here’s a closer look at how port 445 works:

The Client-Server Dance

Client (Your Computer): Firstly, when you want to access a file or printer on another computer, your computer acts as the client. It initiates the request by sending a message through port 445. This message specifies what resource you’re trying to access (e.g., a specific folder or printer) and your credentials (username and password) if necessary.

Server (The Other Computer): Secondly, the other computer on the network functions as the server. It’s constantly listening on port 445 for incoming requests. Upon receiving your request, the server verifies your credentials (if applicable) and checks if you have permission to access the requested resource.

Communication and Data Flow


If everything checks out, the server sends an acknowledgment back through port 445, establishing a connection. In this way, this handshake is like two people agreeing on the terms before sharing something.

Data Transfer

Once connected, the actual data transfer begins. Consequently, the server sends the requested file or allows you to use the printer, with all the data flowing through port 445. It’s like physically handing over the recipe or letting your neighbor use your printer.

Closing the Connection

When you’re done accessing the resource, the client sends a termination message through port 445, and the connection is closed. This is like returning the cup of sugar and saying thank you!

The Role of TCP

While port 445 designates the address for this communication, another protocol called TCP (Transmission Control Protocol) plays a crucial role. Specifically, TCP acts like a reliable delivery service, ensuring the data arrives correctly at its destination.

Additionally, it breaks down the files or printer jobs into smaller packets, sends them through port 445, and then reassembles them on the receiving computer.

As a result, this ensures all the information gets delivered without errors, similar to how a package gets shipped with tracking numbers and verification steps.

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How do I enable Port 445 on Windows 10 ?

Enabling port 445 on Windows 10 involves opening it through the Windows Firewall. This port is essential for the NetBIOS layer, facilitating connections through an IP address for file shares and offering performance improvements.

Consequently, follow the steps below to enable port 445 in Windows 10 using command prompts to enhance your system’s security posture:

Search for Windows Firewall

Click on the Start menu and type “Windows Firewall”. Select “Windows Firewall with Advanced Security” from the search results.

Access Inbound Rules

In the left pane of the Windows Firewall window, click on “Advanced settings”.  As a result, this will open a new window with firewall settings.

Create a New Rule

In the right pane of the new window, find the section titled “Inbound Rules”. Right-click anywhere within that section and select “New Rule” from the context menu.

Select Port Rule

In the “New Inbound Rule Wizard” window, choose “Port” from the list of options and click “Next”.

Specify Port and Protocol

In the next window, select “TCP” from the “Protocol type” dropdown menu.  Since port 445 uses TCP, leave it selected.  Additionaly, in the “Specific local ports” field, enter “445” and click “Next”.

Allow the Connection

On the next screen, choose “Allow the connection” and click “Next”.

Select Network Profiles

Here, you can choose which network profiles this rule applies to. By default, all profiles (Domain, Private, Public) will be selected. Alternatively, you can adjust this selection based on your needs and click “Next”.

Name the Rule

Provide a recognizable name for this rule, such as “Enable File and Printer Sharing”. Additionally, a description is optional but can help with future reference. Click “Finish” to create the rule.

After completing these steps, port 445 will be open for inbound traffic on your chosen network profiles.

Important Note:  Port 445 is commonly used for File and Printer Sharing. However, opening it creates a security risk as it allows access to your computer from other devices on the network. Therefore, it’s recommended to only enable it if you specifically need to share files and printers and understand the potential security implications.

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Can I block port 445 ?

Absolutely, you can block port 445 on Windows 10. Blocking it actually helps improve your computer’s security.

Following the same logic we used for enabling the port, here’s how to block port 445 on Windows 10:

Search for Windows Firewall: First, click the Start menu and type “Windows Firewall”. From the search results, pick “Windows Firewall with Advanced Security”.

Access Inbound Rules Next, in the left pane of the Firewall window, click “Advanced settings”. This will open a new window with more firewall options.

Create a New Rule:  Then, in the new window’s right pane, find the “Inbound Rules” section. Right-click anywhere in that section and select “New Rule”.

Select Port Rule: After that, in the “New Inbound Rule Wizard” window, select “Port” from the list and click “Next”.

Specify Port and Protocol:  Furthermore, on the next screen, choose “TCP” from the “Protocol type” dropdown (this port use TCP). In the “Specific local ports” box, type “445” and click “Next”.

Block the Connection:  NOw, this step blocks instead of allowing. Choose “Block the connection” and click “Next”.

Select Network Profiles:  Additionally, here you can choose which network types the rule applies to. By default, all profiles (Domain, Private, Public) are selected. You can change this if needed, then click “Next”.

Name the Rule:  Finally, give the rule a recognizable name like “Block File and Printer Sharing”. You can optionally add a description. When ready, click “Finish” to create the rule.

After completing these steps, port 445 will be blocked for inbound traffic on your chosen network profiles.

Note: Blocking the port might cause issues if you rely on File and Printer Sharing on your network. Make sure you understand the implications before proceeding.

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How to protect TCP port 445 from exploitation ?

Here are several steps you can take to protect TCP port 445 from exploits:

Block Port 445 When Not Needed

  • This is the most secure approach if you don’t rely on File and Printer Sharing across devices on your network. Blocking it entirely prevents any attempted attacks on this port.
  • This approach safeguards internal network traffic and maintains the integrity of your network adaptor and network devices. It ensures that network file sharing protocols and network requirements are tightly controlled at the firewall level.
  • This action minimizes vulnerabilities related to the NetBIOS name service and its role in network communication within user space. Refer to the above section on how to block this port using Windows Firewall.

Strong Passwords and Multi-Factor Authentication

  • Implement strong and unique passwords for all user accounts on the system: This makes it significantly harder for attackers to gain unauthorized access even if they exploit a vulnerability.
  • Enable Multi-Factor Authentication (MFA) whenever possible: MFA adds an extra layer of security by requiring a second verification factor beyond just a password, like a code from your phone.

Update Regularly

  • Keep your operating system and all software applications up-to-date with the latest security patches. These updates often address vulnerabilities that attackers might exploit.

Limit Network Access

  • Restrict access to File and Printer Sharing only to authorized users and devices on your network. This minimizes the potential damage if an exploit were to occur.

Network Segmentation

  • If you have a large network, consider segmenting it into smaller subnets. This can help isolate devices and prevent a compromised machine, whether it’s an internet-connected device or a mobile device, from infecting others on the network.
  • Additionally, managing serial ports and other network entry points, such as the port for file sharing, can enhance security.
  • Implementing a multi-protocol approach can further secure your network infrastructure.

Disable SMBv1

  • Older SMB versions (SMBv1) are more vulnerable to exploits. If possible, disable SMBv1 and use SMBv2 or SMBv3 which have improved security features.

Antivirus and Anti-malware Software

  • Use a reputable antivirus and anti-malware solution with real-time protection. This can help detect and block malicious activity that might target vulnerabilities in SMB.

Monitor Network Activity

  • Implement a system to monitor network activity for suspicious behavior. This can help identify potential attacks early on before they can cause significant damage.


In conclusion, Port 445 is a critical component for seamless file and printer sharing between Windows devices on a network. While incredibly useful, it also presents potential security risks if not properly secured.

Implement strong passwords, keep software updated, limit network access, and consider disabling SMBv1. For added protection, block the port entirely if you don’t need its sharing capabilities.

It’s better to take small steps to protect yourself from cyber threats, than having to deal with big problems later on.

By understanding Port 445’s functions and following best practices, you can reap its collaborative benefits while mitigating vulnerabilities that could compromise your network’s safety.


Frequently Asked Question’s (FAQ’s)

What is SMB on port 445 ?

SMB (Server Message Block) is a file sharing protocol that uses port 445 to allow computers to access files and printers on a network.  While convenient, keeping it open creates a security risk; consider blocking it if file sharing isn’t essential.

What is 445 port used for ?

Port 445 is commonly used for SMB (Server Message Block), a file sharing protocol that lets devices on a network access files and printers.

Is port 445 a security risk ?

Yes, port 445 (SMB) is a security risk if left open. Hackers can exploit it to gain access to your files and folders. Block it if you don’t rely on file sharing.

Content Writer

Smith Ron, the writer at Assistme360. He has extensive experience in crafting straightforward, step-by-step guides for technical issues. His broad knowledge ensures accurate solutions. Kindly spare a moment to drop a comment down and express your opinions. Your feedback can be valuable in assisting others who may come across similar problems.

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