[{"data":1,"prerenderedAt":25},["ShallowReactive",2],{"content-port-reference-en":3},{"about":4,"steps":7,"faq":12},[5,6],"Network services listen on ports – numbered entrances from 0 to 65535. Web servers use 443, SSH uses port 22, databases like PostgreSQL 5432. Anyone setting up a firewall, troubleshooting or analysing a port scan needs to know which service is behind which number.","The list contains the most important TCP and UDP ports from the IANA registry and common practice – from email and DNS through VPNs and remote access to databases, message brokers and game servers. Search by number, range or keyword. Calculate networks with the [[subnet-calculator]] and query DNS records with the [[dns-lookup]].",[8,9,10,11],"Enter a port number, e.g. 3389, to see the matching service.","Or search for a range such as 5000-6000 or a keyword like “vpn” or “database”.","Hover over the port number to see the IANA range (system, registered, dynamic).","Use the information for firewall rules or troubleshooting.",[13,16,19,22],{"q":14,"a":15},"What is the difference between TCP and UDP?","TCP establishes a connection and makes sure all data arrives completely and in the right order – ideal for websites, email or SSH. UDP sends packets without acknowledgement and is therefore faster, e.g. for DNS, video calls, games or HTTP\u002F3.",{"q":17,"a":18},"What are system, registered and dynamic ports?","Ports 0–1023 are system ports for standard services; on Unix systems programs need special privileges to use them. 1024–49151 are registered with the IANA for specific applications. 49152–65535 are dynamic and assigned by the operating system for outgoing connections.",{"q":20,"a":21},"Which ports should I not expose to the internet?","Databases (3306, 5432, 27017, 6379), remote access such as RDP (3389) and VNC (5900), SMB (445) and the Docker API (2375) never belong on the internet unprotected. Use a VPN like WireGuard or SSH tunnels instead.",{"q":23,"a":24},"Can I check whether a port is open?","Not from the browser – for security reasons, websites may not open arbitrary connections. On your own computer, commands like “ss -tlnp” (Linux), “netstat -an” (Windows) or “lsof -i -P” (macOS) help.",1792173707418]