How to prevent SMS bombing through frequency limiting?

To prevent SMS bombing through frequency limiting, you can implement rate-limiting mechanisms to control the number of SMS messages sent to a specific phone number or IP address within a given time frame. This helps block abusive behavior while allowing legitimate users to receive messages.

How Frequency Limiting Works

1. Per-Phone Number Limit: Restrict the number of SMS messages sent to a single phone number within a certain period (e.g., 5 messages per hour).
2. Per-IP Address Limit: Limit the number of requests from a single IP address to prevent automated attacks.
3. CAPTCHA Integration: Combine frequency limiting with CAPTCHA verification to block bots.

Example Implementation

• If a user exceeds 5 SMS requests per hour, block further attempts and require CAPTCHA verification.
• For API-based SMS services, enforce rate limits at the server level (e.g., using Nginx or a firewall).

Recommended Tencent Cloud Service

Tencent Cloud's SMS service provides built-in frequency limiting and anti-fraud features to prevent SMS bombing. You can configure rules in the console to restrict message sending frequency per phone number or IP. Additionally, Tencent Cloud Anti-DDoS and Web Application Firewall (WAF) can help mitigate malicious traffic before it reaches your SMS service.