Quick Answer: Should I Block Port 139?

Is NetBIOS a security risk?

Vulnerabilities in Windows Host NetBIOS to Information Retrieval is a Low risk vulnerability that is also high frequency and high visibility.

This is the most severe combination of security factors that exists and it is extremely important to find it on your network and fix it as soon as possible..

Should I open port 139?

If you are on Windows-based network that is running NetBios, it is perfectly normal to have port 139 open in order to facilitate that protocol. If you are not on a network using NetBios, there is no reason to have that port open.

What is port 3389 commonly used for?

Port 3389 Details Port is IANA registered for Microsoft WBT Server, used for Windows Remote Desktop and Remote Assistance connections (RDP – Remote Desktop Protocol). Also used by Windows Terminal Server.

What ports do hackers use?

In your security tests, be sure to check these commonly hacked TCP and UDP ports:TCP port 21 — FTP (File Transfer Protocol)TCP port 22 — SSH (Secure Shell)TCP port 23 — Telnet.TCP port 25 — SMTP (Simple Mail Transfer Protocol)TCP and UDP port 53 — DNS (Domain Name System)More items…

What service runs on port 445?

Along with ports 135, 137 and 139, port 445 is a traditional Microsoft networking port with tie-ins to the original NetBIOS service found in earlier versions of Windows OSes. Specifically, TCP port 445 runs server message block (SMB) over TCP/IP. This is a core means for communication on a Microsoft-based LAN.

Is it safe to disable NetBIOS?

Do you still have NetBIOS turned on on all of your workstations and servers in your corporate LAN? This old network protocol puts you at risk and should be killed without prejudice! There are quite a few reasons why NetBIOS is bad for your network. NetBIOS is an inneficient protocol.

Should I block port 135?

Hacker tools such as “epdump” (Endpoint Dump) can immediately identify every DCOM-related server/service running on the user”s hosting computer and match them up with known exploits against those services. Therefore, port 135 should not be exposed to the internet and must be blocked.

How do I block UDP ports?

Blocking ports using Windows Firewall Select New Rule from the Actions pane. Select Port from the Rule Type listing. Select TCP or UDP, and specify the ports, or a port range (e.g. 445, or 137-139). Select block the connection.

What ports are dangerous?

Commonly Abused PortsPort 20,21 – FTP. An outdated and insecure protocol, which utilize no encryption for both data transfer and authentication.Port 22 – SSH. … Port 23 – Telnet. … Port 25 – SMTP. … Port 53 – DNS. … Port 139 – NetBIOS. … Ports 80,443 – Used by HTTP and HTTPS. … Port 445 – SMB.More items…•Oct 14, 2020

What is port 139 commonly used for?

The port 139 is used for File and Printer Sharing but happens to be the single most dangerous Port on the Internet. This is so because it leaves the hard disk of a user exposed to hackers.

What is port 443 normally used for?

About Port 443 Port 443 is used explicitly for HTTPS services and hence is the standard port for HTTPS (encrypted) traffic.

What are ports 137 and 138 used for?

Ports 137, 138, and 139 are used by NetBIOS, which does not support IPv6. CIFS is required for Windows file service. You can disable CIFS by issuing the cifs terminate command on your storage system console.

Why do we need port numbers?

A port is simply a channel of communication which is numbered between 1 and 65000. All network devices use them and most have the ability to change them when required. They were originally created to allow multiple programs to use the same IP address. The best way to understand ports is to think of the postal system.

Is port 445 open by default?

If the server has NBT enabled, it listens on UDP ports 137 and 138, and TCP ports 139 and 445. … All four ports are open as default in all versions of Windows, including Windows 10 and Windows Server 2019.

How do I check if port 139 is open?

For test the port 139, please try use the IP address of the server, NetBIOS or FQDN. You can use the telnet command or PortQuery tools.

Should you disable NetBIOS over TCP IP?

A. Yes. To improve performance, it’s recommended that you disable NetBIOS over TCP/IP on your cluster network NIC and other dedicated-purpose NICs, such as for iSCSI and Live Migration. … To disable NetBIOS over TCP/IP, access the IPv4 properties of your network adapter.

What is the protocol for port 139?

As such, SMB requires network ports on a computer or server to enable communication to other systems. SMB uses either IP port 139 or 445. Port 139: SMB originally ran on top of NetBIOS using port 139. NetBIOS is an older transport layer that allows Windows computers to talk to each other on the same network.

What ports should be blocked?

For example, the SANS Institute recommends blocking outbound traffic that uses the following ports:MS RPC – TCP & UDP port 135.NetBIOS/IP – TCP & UDP ports 137-139.SMB/IP – TCP port 445.Trivial File Transfer Protocol (TFTP) – UDP port 69.Syslog – UDP port 514.More items…•Oct 16, 2015

What are ports 139 and 445 used for?

SMB is a network file sharing protocol that requires an open port on a computer or server to communicate with other systems. SMB ports are generally port numbers 139 and 445. Port 445: Used by newer versions of SMB (after Windows 2000) on top of a TCP stack, allowing SMB to communicate over the Internet.

Should I block port 445?

We also recommend blocking port 445 on internal firewalls to segment your network – this will prevent internal spreading of the ransomware. Note that blocking TCP 445 will prevent file and printer sharing – if this is required for business, you may need to leave the port open on some internal firewalls.

Is NetBIOS needed for SMB?

SMB does rely on NetBIOS for communication with devices that do not support direct hosting of SMB over TCP/IP. NetBIOS is completely independent from SMB. It is an API that SMB, and other technologies can use, so NetBIOS has no dependency to SMB.