Capti block specific inbound ports, including:

  • TCP/23
  • UDP/8291
  • UDP/161
  • UDP/52

Here's a brief overview of why ISPs block ports:

  1. Security: Blocking ports can help prevent unauthorised access to a network or device. For example, TCP port 23 is commonly blocked because it's used for Telnet, a protocol that is not secure and can be exploited by hackers to gain control of devices.
  2. Prevent Abuse: Some ports are blocked to prevent the network from being used for malicious activities, such as sending spam or participating in DDoS attacks. By blocking these ports, ISPs can reduce the likelihood of their network being used for these purposes.
  3. Reduce Vulnerability Exposure: Certain ports are associated with services known to have vulnerabilities. Blocking these ports at the ISP level helps protect users from attacks that exploit these vulnerabilities.
  4. Compliance: In some cases, ports may be blocked to comply with regulations or industry standards that require specific security measures to be in place.