What is port 2869 used for?


NetBIOS stands for Network Basic Input Output System. With this software protocol, applications, PCs and desktops in a local area network (LAN) can communicate with the network hardware and transmit data over the network. Software applications running on a NetBIOS network search for and identify themselves by their NetBIOS names. A NetBIOS name is up to 16 characters long and is usually independent of the computer name. Two applications start a NetBIOS session when one (the client) sends a command to "call" another client (the server) TCP port 139.

What is port 139 used for?

NetBIOS However, there is an enormous security risk in your WAN or over the Internet. All kinds of information, such as your domain, workgroup and system names, and account information, can be accessed through NetBIOS. So it is important that you run your NetBIOS on the preferred network and make sure it never leaves your network.

For security reasons, firewalls always block this port first after you have opened it. Port 139 is used for File and printer sharing but is the most dangerous single port on the internet. This is because a user's hard drive is exposed to hackers.

As soon as an attacker finds an active port 139 on a device, it can run NBSTAT a diagnostic tool for NetBIOS over TCP / IP, designed primarily to troubleshoot NetBIOS name resolution problems. This is an important first step in an attack - footprint.

The NBSTAT command would allow the attacker to obtain some or all of the critical information related to them

  1. A list of local NetBIOS names
  2. Computer name
  3. A list of names that have been resolved by WINS
  4. IP addresses
  5. Contents of the session table with the destination IP addresses

With the above details, all important information about the operating system, services and important applications running on the system are available to the attacker. In addition to these, it also has private IP addresses that the LAN / WAN and security engineers have tried to hide behind NAT. User IDs are also included in the lists that are provided when you run NBSTAT.

This makes it easier for hackers to remotely access the contents of hard drive directories or drives. Using some freeware tools, you can then unnoticed upload and run any program of your choice without the computer owner noticing.

If you are using a multihomed computer, disable NetBIOS on each network card or the dial-up connection under the TCP / IP properties that are not part of your local network.

What is an SMB Port?

While port 139 is technically known as "NBT over IP", port 445 is "SMB over IP". SMB stands for 'Server message blocks’. Server Message Block in Modern Language is also known as Common internet file system. The system operates as an application-level network protocol, primarily used for sharing files, printers, serial ports, and other types of communication between nodes on a network.

Most of the use of SMB involves computers Microsoft Windowswhere it was called "Microsoft Windows Network" before the later introduction of Active Directory. It can be run in several ways above the session (and lower) network tiers.

For example, SMB on Windows can run directly over TCP / IP without the need for NetBIOS over TCP / IP. As you point out, port 445 is used. On other systems you can find services and applications that use port 139. This means that SMB is running with NetBIOS over TCP / IP.

Malicious hackers admit that port 445 is vulnerable and has a lot of insecurities. A terrible example of port 445 being misused is the relatively silent occurrence of NetBIOS worms. These worms scan the Internet slowly but in a defined way for instances of port 445, using tools like PsExec to transfer to the victim's new computer, and then redouble their scanning efforts. This not very well known method makes thisBot armies“The tens of thousands of NetBIOS worm infested machines are being assembled and inhabited the Internet.

How do you deal with port 445?

In view of the dangers mentioned above, it is in our interest not to expose port 445 to the Internet, instead port 445, like Windows port 135, is deeply embedded in Windows and is difficult to close securely. That is, its closure is possible, however, other dependent services such as e DHCP Dynamic Host Configuration Protocol (), which is often used to automatically obtain an IP address from the DHCP servers used by many companies and ISPs, has stopped working.

Considering all of the security reasons outlined above, many ISPs find it necessary to block this port for their users. This only happens if port 445 is not protected by a NAT router or personal firewall. In such a situation, your ISP may be preventing traffic on port 445 from reaching you.


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