All ports
Port4990/UDP
busycalPort
4990
Protocol
UDP
Category
Registered
Service
busycal
What is port 4990?
Port 4990/UDP is a Registered port, registered with IANA for specific applications. It is associated with the busycal service.
BusySync Calendar Synch. Protocol
Useful commands
nmapnmap -p 4990 -sV example.comnetcatnc -zv example.com 4990curlcurl -v http://example.com:4990/telnettelnet example.com 4990bash(echo > /dev/udp/example.com/4990) 2>/dev/nullFirewall commands
UFWAllow
sudo ufw allow 4990/udpDeny
sudo ufw deny 4990/udpiptablesAllow
sudo iptables -A INPUT -p udp --dport 4990 -j ACCEPTDeny
sudo iptables -D INPUT -p udp --dport 4990 -j ACCEPTfirewalldAllow
sudo firewall-cmd --permanent --add-port=4990/udpWindowsAllow
netsh advfirewall firewall add rule name="Open Port 4990" dir=in action=allow protocol=UDP localport=4990Security Risks
- Unauthorized access to the service
- Data exposure if the service is unauthenticated
- Outdated versions with vulnerabilities
- Incorrect service configuration
Frequently Asked Questions
What service runs on port 4990/UDP?
Port 4990/UDP is associated with the busycal service. BusySync Calendar Synch. Protocol
Is it safe to expose port 4990 to the Internet?
It depends on the service and configuration. Port 4990 (busycal) is a Registered port. If you need to expose it, keep the service updated, use strong authentication, and configure a firewall. It's always recommended to restrict access by IP when possible.
How do I check if port 4990 is open?
You can use nmap: `nmap -p 4990 -sV example.com`, netcat: `nc -zv example.com 4990`, or the bash command: `(echo > /dev/udp/example.com/4990) 2>/dev/null && echo "Open" || echo "Closed"`.
How do I open or close port 4990 on my firewall?
On Linux with UFW: `sudo ufw allow 4990/udp` (open) or `sudo ufw deny 4990/udp` (close). With iptables: `sudo iptables -A INPUT -p udp --dport 4990 -j ACCEPT`. On Windows: `netsh advfirewall firewall add rule name="Open Port 4990" dir=in action=allow protocol=UDP localport=4990`.
What applications and services use port 4990?
Port 4990/UDP is used by the busycal service. Specific uses depend on the software and configuration. Check our related tools section for more information.