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You see this message on the Trend Micro Home Network Security app:

"Open Port TELNET 23/TCP and SSH 22/TCP"

Why did this happen?

An open port TELNET 23/TCP and SSH 22/TCP are detected in your network.

What is a port?

A service called port is used to allow network communications for Internet-connected devices. This port is used as an entry point on sending or receiving data between the communication sources, and destinations.

What are the possible risks?

A vulnerability in the Internet-connected devices with unsecure setting or weak configuration can cause unauthorized access that can exploit, and compromise this open port.

Normally, TELNET 23/TCP and SSH 22/TCP are used for setting up routers and IoT devices, and it can be exploited to spread IoT malware like "Mirai", and its variants.

What should I do next?

  1. If your device is currently using this port, make sure your device is updated to the latest firmware.
  2. Stop unnecessary service (Open Port 22 or 23) or do appropriate access management.

    You may check your router's manual for firewall configuration or visit the manufacturer's website to check for this information.

  3. Set a strong password on all your devices:
    • It must have at least 8 characters.
    • Use uppercase letters, lowercase letters, and a mix of numbers and symbols.
  4. If you are not using the device, disconnect the device from your network.
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