All ports
Port4840/UDP
opcua-udpPort
4840
Protocol
UDP
Category
Registered
Service
opcua-udp
What is port 4840?
Port 4840/UDP is a Registered port, registered with IANA for specific applications. It is associated with the opcua-udp service.
OPC UA Multicast Datagram Protocol
Useful commands
nmapnmap -p 4840 -sV example.comnetcatnc -zv example.com 4840curlcurl -v http://example.com:4840/telnettelnet example.com 4840bash(echo > /dev/udp/example.com/4840) 2>/dev/nullFirewall commands
UFWAllow
sudo ufw allow 4840/udpDeny
sudo ufw deny 4840/udpiptablesAllow
sudo iptables -A INPUT -p udp --dport 4840 -j ACCEPTDeny
sudo iptables -D INPUT -p udp --dport 4840 -j ACCEPTfirewalldAllow
sudo firewall-cmd --permanent --add-port=4840/udpWindowsAllow
netsh advfirewall firewall add rule name="Open Port 4840" dir=in action=allow protocol=UDP localport=4840Security 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- Outdated versions with vulnerabilities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 4840/UDP?
Port 4840/UDP is associated with the opcua-udp service. OPC UA Multicast Datagram Protocol
Is it safe to expose port 4840 to the Internet?
It depends on the service and configuration. Port 4840 (opcua-udp) 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 4840 is open?
You can use nmap: `nmap -p 4840 -sV example.com`, netcat: `nc -zv example.com 4840`, or the bash command: `(echo > /dev/udp/example.com/4840) 2>/dev/null && echo "Open" || echo "Closed"`.
How do I open or close port 4840 on my firewall?
On Linux with UFW: `sudo ufw allow 4840/udp` (open) or `sudo ufw deny 4840/udp` (close). With iptables: `sudo iptables -A INPUT -p udp --dport 4840 -j ACCEPT`. On Windows: `netsh advfirewall firewall add rule name="Open Port 4840" dir=in action=allow protocol=UDP localport=4840`.
What applications and services use port 4840?
Port 4840/UDP is used by the opcua-udp service. Specific uses depend on the software and configuration. Check our related tools section for more information.