All ports
Port20/TCP
ftp-dataPort
20
Protocol
TCP
Category
Well-Known
Service
ftp-data
What is port 20?
Port 20/TCP is a Well-Known port, assigned by IANA for widely recognized services. It is associated with the ftp-data service.
File Transfer [Default Data]
Useful commands
nmapnmap -p 20 -sV example.comnetcatnc -zv example.com 20curlcurl -v http://example.com:20/telnettelnet example.com 20bash(echo > /dev/tcp/example.com/20) 2>/dev/nullFirewall commands
UFWAllow
sudo ufw allow 20/tcpDeny
sudo ufw deny 20/tcpiptablesAllow
sudo iptables -A INPUT -p tcp --dport 20 -j ACCEPTDeny
sudo iptables -D INPUT -p tcp --dport 20 -j ACCEPTfirewalldAllow
sudo firewall-cmd --permanent --add-port=20/tcpWindowsAllow
netsh advfirewall firewall add rule name="Open Port 20" dir=in action=allow protocol=TCP localport=20Security 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- Outdated versions with vulnerabilities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 20/TCP?
Port 20/TCP is associated with the ftp-data service. File Transfer [Default Data]
Is it safe to expose port 20 to the Internet?
It depends on the service and configuration. Port 20 (ftp-data) is a Well-Known 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 20 is open?
You can use nmap: `nmap -p 20 -sV example.com`, netcat: `nc -zv example.com 20`, or the bash command: `(echo > /dev/tcp/example.com/20) 2>/dev/null && echo "Open" || echo "Closed"`.
How do I open or close port 20 on my firewall?
On Linux with UFW: `sudo ufw allow 20/tcp` (open) or `sudo ufw deny 20/tcp` (close). With iptables: `sudo iptables -A INPUT -p tcp --dport 20 -j ACCEPT`. On Windows: `netsh advfirewall firewall add rule name="Open Port 20" dir=in action=allow protocol=TCP localport=20`.
What applications and services use port 20?
Port 20/TCP is used by the ftp-data service. Specific uses depend on the software and configuration. Check our related tools section for more information.