RKN Checker

A modern Android application designed to diagnose network censorship, DPI filtering, and ISP blocking signatures in Russia, inspired by rkn-block-checker.

🚀 Features Connection & ISP Info: Automatically detects public IP address, ISP/Provider name, and geolocation. Multi-layer Probing Engine: DNS & DoH (DNS-over-HTTPS): Compares local System DNS with Cloudflare DoH (https://cloudflare-dns.com/dns-query). Detects DNS poisoning, fake NXDOMAIN, and transparent DNS rewriting. TCP Probing (Port 443): Connects to target hosts over TCP, measures latency (TCP ms), and detects TCP RST injection or timeouts. TLS Handshake & SNI Probing: Wraps connection in TLS with explicit SNI hostname (SNIHostName), measuring TLS latency (TLS ms). Detects TSPU/RKN DPI filtering signatures (TLS reset right after ClientHello or silent handshake drops). HTTP & ISP Stub Page Detection: Issues HTTP requests without infinite redirect loops. Scans response status codes (e.g. HTTP 451) and response body snippets for known ISP block page markers ("доступ ограничен", "решению роскомнадзора", "заблокирован", etc.). Pre-configured Target Lists: Whitelist (21 domains): Key Russian services that should normally work (gosuslugi, sberbank, yandex, ozon, vk, rkn, nalog, etc.). Blacklist (15 domains): Well-known RKN-restricted services (instagram, facebook, twitter/x, linkedin, discord, meduza, rutracker, tor-project, protonvpn, etc.). Modern Jetpack Compose UI: Network Info Card: Displays IP, ISP, and Location. Diagnostic Summary Overview: Provides at-a-glance status for Whitelist/Blacklist, overall ISP filter verdict, and block type tags (TLS DPI, HTTP Stub, DNS Block, TCP Timeout). Filter Tabs: Filter targets by All, Whitelist, Blacklist, or Blocked. Card-Based Site View: Displays status badges (✓ OK, ~ TLS DPI, ✗ HTTP STUB, ⛔ DNS BLOCK), latency pills (TCP, TLS, PLT, Status), and structured diagnostic notes.