Should I block port 123?

Port 123: NTP UDP This port is associated with NTP, the network time protocol. Due to ongoing security vulnerabilities, incoming connections are only permitted to connect to approved campus NTP servers. (Outgoing requests from on-campus machines to off-campus NTP servers will not be blocked.)

Can UDP ports be blocked?

To block UDP traffic, you also need to block certain UDP ports in your router or firewall. To make it simple, you’re recommended to block udp ports 1024-65534 in your router/firewall. Since most internet applications work in tcp protocol, blocking of these udp ports will not influence your internet access.

Which protocol uses UDP port 123?

NTP is a widely deployed time synchronization service listening on UDP port 123. The attacker spoofs source IPs and sends a small query to a vulnerable NTP server, which generates a large reply of response data to the spoofed addresses.

Why is my UDP port 123 still open?

it means that your firewall is blocking the windows time service. it means that your time wont sync with the NTP servers. if youre confident in the clock on your PC, theres no reason to have port 123 open. just close it. then if you want to stop the firewall errors, just stop the windows time service.

How to find open and blocked TCP / UDP ports?

1 Open the Start Menu and search for CMD. 2 Now, right-click on CMD and Run as Administrator. 3 With the Command Prompt open, type:

What does it mean when a port is blocked on a network?

Blocked: In to unapproved servers. This port is associated with NTP, the network time protocol. Due to ongoing security vulnerabilities, incoming connections are only permitted to connect to approved campus NTP servers. (Outgoing requests from on-campus machines to off-campus NTP servers will not be blocked.) Blocked: Inbound.

When is UDP communication is blocked by the Windows Firewall?

Inbound TCP and ICMP communications may also be blocked in this situation. This problem occurs if the inbound UDP communication is enabled by Windows Firewall. One of the services that may be affected by this issue is Windows Server Failover Clustering (WSFC).