Port 53 — DNS

TCP/UDP · Port 53 is used for DNS (Domain Name System) queries and responses over TCP or UDP. This port is critical for resolving domain names to IP addresses, making it essential for internet communication. Security relevance lies in the potential for DNS spoofing attacks.

Port Number: 53
Service Name: DNS
Protocol: TCP/UDP
Common Software: BIND, Unbound, dnsmasq, PowerDNS

Security Notes

DNS amplification attacks are common. Rate limit and implement DNSSEC.

FAQ

What is port 53 used for?

Port 53 is used for DNS. Port 53 is used for DNS (Domain Name System) queries and responses over TCP or UDP. This port is critical for resolving domain names to IP addresses, making it essential for internet communication. Security relevance lies in the potential for DNS spoofing attacks. Common software: BIND, Unbound, dnsmasq, PowerDNS.

Is port 53 dangerous to leave open?

DNS amplification attacks are common. Rate limit and implement DNSSEC.

How do I check if port 53 is open?

Use nmap: nmap -p 53 <target> or check locally: ss -tlnp | rg 53