Port39/UDP

rlp

Port

Protocol

UDP

What is port 39?

Port 39/UDP is a Well-Known port, assigned by IANA for widely recognized services. It is associated with the rlp service.

Resource Location Protocol

Useful commands

nmapnmap -p 39 -sV example.com

netcatnc -zv example.com 39

curlcurl -v http://example.com:39/

telnettelnet example.com 39

bash(echo > /dev/udp/example.com/39) 2>/dev/null

Firewall commands

UFWAllow

sudo ufw allow 39/udp

Deny

sudo ufw deny 39/udp

iptablesAllow

sudo iptables -A INPUT -p udp --dport 39 -j ACCEPT

Deny

sudo iptables -D INPUT -p udp --dport 39 -j ACCEPT

firewalldAllow

sudo firewall-cmd --permanent --add-port=39/udp

WindowsAllow

netsh advfirewall firewall add rule name="Open Port 39" dir=in action=allow protocol=UDP localport=39

Security 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Outdated versions with vulnerabilities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 39/UDP?

Port 39/UDP is associated with the rlp service. Resource Location Protocol

Is it safe to expose port 39 to the Internet?

It depends on the service and configuration. Port 39 (rlp) 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 39 is open?

You can use nmap: `nmap -p 39 -sV example.com`, netcat: `nc -zv example.com 39`, or the bash command: `(echo > /dev/udp/example.com/39) 2>/dev/null && echo "Open" || echo "Closed"`.

How do I open or close port 39 on my firewall?

On Linux with UFW: `sudo ufw allow 39/udp` (open) or `sudo ufw deny 39/udp` (close). With iptables: `sudo iptables -A INPUT -p udp --dport 39 -j ACCEPT`. On Windows: `netsh advfirewall firewall add rule name="Open Port 39" dir=in action=allow protocol=UDP localport=39`.