All ports
Port853/TCP
domain-sPort
853
Protocol
TCP
Category
Well-Known
Service
domain-s
What is port 853?
Port 853/TCP is a Well-Known port, assigned by IANA for widely recognized services. It is associated with the domain-s service.
DNS query-response protocol run over TLS
Useful commands
nmapnmap -p 853 -sV example.comnetcatnc -zv example.com 853curlcurl -v http://example.com:853/telnettelnet example.com 853bash(echo > /dev/tcp/example.com/853) 2>/dev/nullFirewall commands
UFWAllow
sudo ufw allow 853/tcpDeny
sudo ufw deny 853/tcpiptablesAllow
sudo iptables -A INPUT -p tcp --dport 853 -j ACCEPTDeny
sudo iptables -D INPUT -p tcp --dport 853 -j ACCEPTfirewalldAllow
sudo firewall-cmd --permanent --add-port=853/tcpWindowsAllow
netsh advfirewall firewall add rule name="Open Port 853" dir=in action=allow protocol=TCP localport=853Security Risks
- DNS cache poisoning attacks
- DDoS amplification using open DNS resolvers
- Information disclosure of internal subdomains
- Domain hijacking if DNS server is misconfigured
Frequently Asked Questions
What service runs on port 853/TCP?
Port 853/TCP is associated with the domain-s service. DNS query-response protocol run over TLS
Is it safe to expose port 853 to the Internet?
It depends on the service and configuration. Port 853 (domain-s) 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 853 is open?
You can use nmap: `nmap -p 853 -sV example.com`, netcat: `nc -zv example.com 853`, or the bash command: `(echo > /dev/tcp/example.com/853) 2>/dev/null && echo "Open" || echo "Closed"`.
How do I open or close port 853 on my firewall?
On Linux with UFW: `sudo ufw allow 853/tcp` (open) or `sudo ufw deny 853/tcp` (close). With iptables: `sudo iptables -A INPUT -p tcp --dport 853 -j ACCEPT`. On Windows: `netsh advfirewall firewall add rule name="Open Port 853" dir=in action=allow protocol=TCP localport=853`.
What applications and services use port 853?
Port 853/TCP is used by the domain-s service. Specific uses depend on the software and configuration. Check our related tools section for more information.