All ports
Port101/UDP
hostnamePort
101
Protocol
UDP
Category
Well-Known
Service
hostname
What is port 101?
Port 101/UDP is a Well-Known port, assigned by IANA for widely recognized services. It is associated with the hostname service.
NIC Host Name Server
Useful commands
nmapnmap -p 101 -sV example.comnetcatnc -zv example.com 101curlcurl -v http://example.com:101/telnettelnet example.com 101bash(echo > /dev/udp/example.com/101) 2>/dev/nullFirewall commands
UFWAllow
sudo ufw allow 101/udpDeny
sudo ufw deny 101/udpiptablesAllow
sudo iptables -A INPUT -p udp --dport 101 -j ACCEPTDeny
sudo iptables -D INPUT -p udp --dport 101 -j ACCEPTfirewalldAllow
sudo firewall-cmd --permanent --add-port=101/udpWindowsAllow
netsh advfirewall firewall add rule name="Open Port 101" dir=in action=allow protocol=UDP localport=101Security 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- Outdated versions with vulnerabilities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 101/UDP?
Port 101/UDP is associated with the hostname service. NIC Host Name Server
Is it safe to expose port 101 to the Internet?
It depends on the service and configuration. Port 101 (hostname) 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 101 is open?
You can use nmap: `nmap -p 101 -sV example.com`, netcat: `nc -zv example.com 101`, or the bash command: `(echo > /dev/udp/example.com/101) 2>/dev/null && echo "Open" || echo "Closed"`.
How do I open or close port 101 on my firewall?
On Linux with UFW: `sudo ufw allow 101/udp` (open) or `sudo ufw deny 101/udp` (close). With iptables: `sudo iptables -A INPUT -p udp --dport 101 -j ACCEPT`. On Windows: `netsh advfirewall firewall add rule name="Open Port 101" dir=in action=allow protocol=UDP localport=101`.
What applications and services use port 101?
Port 101/UDP is used by the hostname service. Specific uses depend on the software and configuration. Check our related tools section for more information.