What is port 5900 for?
Port 5900 is commonly used for remote desktop connections using the Remote Frame Buffer (RFB) protocol. It is associated with the Virtual Network Computing (VNC) system, which allows users to control a computer over a network and file transfer remotely. Of course, port 5900 is used by many other Apple applications, for example, Apple Remote Desktop 2.0 or later (Observe/Control feature) and Screen Sharing (Mac OS X 10.5 or later).
There are two types of port 5900, TCP port 5900 and UDP port 5900.
TCP port 5900 uses the Transmission Control Protocol. It is connection-oriented, requiring handshaking to set up end-to-end communications. Imagine it as the language computers use to converse more effectively with one another.
UDP port 5900 would not have guaranteed communication as TCP. UDP port 5900 uses User Datagram Protocol, a minimal message-oriented Transport Layer protocol. It is connectionless and does not guarantee reliable communication. It is frequently used in time-critical applications like audio/video streaming and real-time gaming, where deleting certain packets is preferable to waiting for delayed data.
Is port 5900 vulnerable?
Does VNC port 5900 have a vulnerability? Unfortunately, VNC port 5900 has vulnerabilities. Here are some famous VNC port 5900 vulnerability examples.
Remote attackers can crash RealVNC 4.0 and earlier by making many connections to port 5900. The incident is documented in CVE-2022-23242.
Vino could allow a remote attacker to circumvent security constraints created by mistake in the vino-preferences dialog box while giving network accessibility information. By sending a specially-crafted UPnP request to TCP port 5900, an attacker could exploit this vulnerability to bypass security restrictions to scan internal hosts or proxy Internet traffic and gain unauthorized access to the vulnerable application. The incident is documented in CVE-2011-1164.
EchoVNC Viewer is vulnerable to a denial of service caused by an error when allocating heap buffer size. A remote attacker could exploit this issue by connecting to a malicious server and sending a bogus request to TCP port 5900, causing the program to crash.
Although VNC port 5900 has security vulnerabilities, correctly configuring and using your software will significantly eliminate the bad influence it brings.
AnyViewer: A safe VNC-based remote desktop software
AnyViewer is a free yet professional remote access tool that uses the VNC protocol. AnyViewer is safe and secure because it is secured with end-to-end encryption via strong 256-Bit Elliptic Curve Cryptography (ECC) algorithm, protecting your data security. Up to now, there’s no AnyViewer vulnerability incident.
As a powerful remote desktop software, AnyViewer also allows you to:
- Control the remote computer without permission;
- Transfer files between computers;
- Connect to multiple computers simultaneously;
- Switch between multiple monitors;
- Communicate with the remote user via texts;
Try this free tool right now; it won’t disappoint you!
Step 1. Download, install, and launch AnyViewer on both computers. Go to Log in, and then click Sign up. (If you already have signed up on its official website, you can log in directly.)
Step 2. Fill in the signup information.
Step 3. Then you can see you successfully logged in to AnyViewer. Your device will automatically be assigned to the account you've logged in.
Step 4. Log in to the same AnyViewer account on the two devices, and then you can achieve a direct connection by clicking One-click control.
Note: You can also upgrade your account to a Professional or Enterprise plan. Then you'll have the following rights:
- You can assign more devices to the same account and then achieve a one-click connection to more computers.
- You can initiate more concurrent remote sessions.
- You can connect to another computer in privacy mode, which means you can black the screen and block the mouse and keyboard of the remote computer to protect your privacy.
- You can enjoy faster file transfer speed.
The bottom line
This post primarily introduces what port 5900 is and its vulnerabilities. Besides, it also introduces a secure VNC-based remote desktop software AnyViewer. AnyViewer is secured by a robust ECC algorithm. With it, you can safely connect to the remote computer without worrying about data loss.