Basics:

  • ports are basically gateways identified by a number from 0 to 65,636 thats used by the Transport layer (TCP/UDP) to direct network traffic to specific services or apps on a host
  • enables a single device to run a shitton of services at once by associating each service with a unique port
  • ports are also categorized into these ranges:
    • 0 > 1023:
      • these are standard ports reserved for really common and widely used protocols and services like HTTP, FTP, SMTP etc.
    • 1024 > 49151:
      • these are registered ports assigned to less common or proprietary apps
    • 49152 > 65,535:
      • used for short term use
  • a client initiates a connection to a specific service by targeting the IP and the port number the service is running on for example 192.168.0.1:80 for http on my local network
  • dont keep open unmonitored ports. they’re a security risk. only open them if necessary for required services.
  • use secure versions of protocols

common protocols:

DNS:

other notable ones:

windows services: