What happens if I close all ports?
If all ports are closed, all packets which are received by attackers are dropped because there are no services attached to the port.
You should always see all ports closed unless you have a server function running and you port forwarded the ports. Its not like you have a web server in your house so why would you expect the port to be open. It is likely some issue with the firewall on you PC especially if VPN works.
Open ports aren't dangerous by default, rather it's what you do with the open ports at a system level, and what services and apps are exposed on those ports, that should prompt people to label them dangerous or not. The reason people call for closed ports because less open ports reduces your attack surface.
Leaving ports open can leave your router – and with it, your computer - vulnerable to hackers and malware attacks.
Ports 80, 443, 8080 and 8443 (HTTP and HTTPS)
HTTP and HTTPS are the hottest protocols on the internet, so they're often targeted by attackers. They're especially vulnerable to cross-site scripting, SQL injections, cross-site request forgeries and DDoS attacks.
If port 80 is open, that means your router allows incoming and/or outgoing connections using that port. If you are running a server application that uses HTTP, it is usually necessary for port 80 to be open.
Malicious ("black hat") hackers commonly use port scanning software to find which ports are "open" (unfiltered) in a given computer, and whether or not an actual service is listening on that port. They can then attempt to exploit potential vulnerabilities in any services they find.
If you have unnecessary router ports open, it could become a security or privacy risk, as hackers could be provided remote access. The best solution is to close unused ports via the router itself. Make sure your network is operating properly and that you set aside your router's IP address, password, and network name.
- 20 – FTP (File Transfer Protocol)
- 22 – Secure Shell (SSH)
- 25 – Simple Mail Transfer Protocol (SMTP)
- 53 – Domain Name System (DNS)
- 80 – Hypertext Transfer Protocol (HTTP)
- 110 – Post Office Protocol (POP3)
- 143 – Internet Message Access Protocol (IMAP)
- 443 – HTTP Secure (HTTPS)
Having an open port does not mean a vulnerability, although vulnerability management and strong credentials are necessary to prevent attacks. Especially important is rapid patching of network applications.
Is port 443 a security risk?
With port 443, the connection is much more secure as the information is encrypted through SSL/TLS (secure sockets layer/transport layer security). With port 80, all information is transferred in plaintext and available to anyone to see. Port 443 is the global standard port for HTTPS traffic.
Leaving port 5000 open is extremely dangerous and is de facto a direct invitation to have your 3CX system hacked.
- FTP (20, 21) FTP stands for File Transfer Protocol. ...
- SSH (22) SSH stands for Secure Shell. ...
- SMB (139, 137, 445) SMB stands for Server Message Block. ...
- DNS (53) DNS stands for Domain Name System. ...
- HTTP / HTTPS (443, 80, 8080, 8443) ...
- Telnet (23) ...
- SMTP (25) ...
- TFTP (69)
Allowing port 80 doesn't introduce a larger attack surface on your server, because requests on port 80 are generally served by the same software that runs on port 443. Closing port 80 doesn't reduce the risk to a person who accidentally visits your website via HTTP.
Port 80 and 443 are ports generally associated with "the Internet". Port 443/HTTPS is the HTTP protocol over TLS/SSL. Port 80/HTTP is the World Wide Web. Let's face it, port 80/443 are generally a given for being open on any type of filtering device allowing traffic outbound on your network.
Closing port 80 doesn't reduce the risk to a person who accidentally visits your website via HTTP. In normal circumstances, that person would receive a redirect to HTTPS, and their subsequent traffic will be protected.
In theory - yes, your computer can still be hacked even, if all TCP and UDP ports are closed and you don't have any malware running on it. However, odds of getting your computer hacked, if all ports are closed, is way lower compared to a system where a web server is listening on publicly accessible port.
A port can be closed after port forwarding due to having multiple routers connected, configuring the incorrect IP address or because the firewall settings are blocking the port. When multiple routers are connected, you will need to send all incoming signals from router 1 to router 2.
From the Windows Control Panel, navigate to the “System and Security -> Windows Firewall” section and click the “Advanced Settings” menu item. In the “View and create firewall rules” section, select the “Inbound Rules” menu item. From the list of inbound rules, find the rule for the port you wish to close.