All ports
Port139/TCP
netbios-ssnPort
139
Protocol
TCP
Category
Well-Known
Service
netbios-ssn
What is port 139?
Port 139/TCP is a Well-Known port, assigned by IANA for widely recognized services. It is associated with the netbios-ssn service.
NETBIOS Session Service
Useful commands
nmapnmap -p 139 -sV example.comnetcatnc -zv example.com 139curlcurl -v http://example.com:139/telnettelnet example.com 139bash(echo > /dev/tcp/example.com/139) 2>/dev/nullFirewall commands
UFWAllow
sudo ufw allow 139/tcpDeny
sudo ufw deny 139/tcpiptablesAllow
sudo iptables -A INPUT -p tcp --dport 139 -j ACCEPTDeny
sudo iptables -D INPUT -p tcp --dport 139 -j ACCEPTfirewalldAllow
sudo firewall-cmd --permanent --add-port=139/tcpWindowsAllow
netsh advfirewall firewall add rule name="Open Port 139" dir=in action=allow protocol=TCP localport=139Security 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- Outdated versions with vulnerabilities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 139/TCP?
Port 139/TCP is associated with the netbios-ssn service. NETBIOS Session Service
Is it safe to expose port 139 to the Internet?
It depends on the service and configuration. Port 139 (netbios-ssn) 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 139 is open?
You can use nmap: `nmap -p 139 -sV example.com`, netcat: `nc -zv example.com 139`, or the bash command: `(echo > /dev/tcp/example.com/139) 2>/dev/null && echo "Open" || echo "Closed"`.
How do I open or close port 139 on my firewall?
On Linux with UFW: `sudo ufw allow 139/tcp` (open) or `sudo ufw deny 139/tcp` (close). With iptables: `sudo iptables -A INPUT -p tcp --dport 139 -j ACCEPT`. On Windows: `netsh advfirewall firewall add rule name="Open Port 139" dir=in action=allow protocol=TCP localport=139`.
What applications and services use port 139?
Port 139/TCP is used by the netbios-ssn service. Specific uses depend on the software and configuration. Check our related tools section for more information.