Network Port

A network port is a number from 0 to 65535 that, combined with an IP address and a protocol (TCP or UDP), identifies where traffic should be delivered on a host. A service listens on a port; clients connect to it.

Why it matters

Ports let one server run a web server, a mail server and SSH at once. Well-known ports below 1024 are assigned by convention, such as 80 for HTTP and 443 for HTTPS. Firewalls filter by port, so an unreachable service often turns out to be a closed or blocked port rather than a broken application.

Example

$ ss -ltn
LISTEN 0 511 0.0.0.0:443

Common mistakes

• Binding a service to 127.0.0.1 and wondering why it is unreachable from other machines.
• Opening high-numbered management ports to the Internet.
• Confusing the TCP and UDP port spaces. TCP 53 and UDP 53 are different endpoints.

Related

• Socket
• TCP
• Firewall
• Port forwarding
• टूल: Port checker

यह पेज सामान्य जानकारी है, जिसे हमारी संपादकीय टीम ने लिखा है और दस्तावेज़ीकरण बदलने पर अपडेट किया जाता है। सर्वर और प्रदाता अलग-अलग होते हैं, इसलिए बदलाव पहले सुरक्षित तरीके से जाँचें। देखें: संपादकीय नीति और अस्वीकरण.