IP Scanner & Service Watcher is a fast, no-nonsense field toolkit for IT support engineers, network admins, CCTV/camera technicians, and home-lab tinkerers. Diagnose the network you are connected to, probe public-facing ports, inspect TLS certificates, and keep an eye on the services that matter — all from your phone.

Every check runs natively when possible (Android native LAN scanner, native TLS inspector, native ping) so results are accurate and fast even on busy networks.

**LAN at a glance**
- Discover every device on the current subnet or any custom CIDR range
- Identify hosts by IP, MAC, and vendor (OUI lookup), with offline/online status
- Loop discovery scans in the background and surface changes over time
- Filter the device list by online, offline, or "has open ports"

**Port scanning that fits the job**
- Built-in profiles for IT (SSH/HTTP/HTTPS/RDP…), CCTV (RTSP/Onvif/HTTP), and other common stacks
- Custom port lists and ranges (e.g. 22,80,443,554,8000-8002) or scan all 65535
- Per-device "Scan ports" shortcut from the discovery list
- Background loop scanning with the manual scan button locked while a loop is running, so checks never overlap

**WAN visibility**
- Public IPv4 / IPv6 detection with one-tap refresh
- WAN port reachability check via a hardened external probe — confirms what the internet actually sees
- WAN port loop with structured history per host:port

**Network tools suite**
- Ping (IPv4 & IPv6) — native ICMP
- DNS Lookup (Cloudflare DoH, all common record types)
- Traceroute (IPv4 & IPv6)
- Website Check, Site Alive, Endpoint Health, Content Match
- SSL/TLS Check — full certificate chain, validity dates, days-to-expiry, hostname match, trust status, protocol/cipher
- Domain Expiry (RDAP)
- Subnet Calculator, Wake-on-LAN, MAC vendor lookup

**Watchers — keep an eye on what matters**
- Convert any tool run into a recurring Watcher: pick the target, pick the interval, done
- Per-tool default intervals (30s up to 7 days) with sensible minimums for tools that hit external services
- State machine: healthy / failing / recovered / paused, with cooldowns and failure thresholds to avoid alert spam
- Notifications you can dial in: toast, vibration, sound, and system notification — globally and per-watcher
- Watcher log captures the exact failure (timed-out, TLS handshake failed, certificate untrusted, DNS unresolved, …) so you know what broke
- Filter the Tools tab by "has watcher" to find them at a glance

**Diagnostics you can trust**
- TLS errors are categorized at the native layer (DNS_FAILED, CERT_EXPIRED, CERT_UNTRUSTED, HANDSHAKE_FAILED, CONNECTION_REFUSED, …) instead of vague "Network request failed"
- HTTP failures auto-probe DNS and TLS to tell you whether DNS, TCP, or the cert is the actual culprit
- Every output is copyable and saved to history

**Built for the way technicians work**
- English and Vietnamese UI
- Scales cleanly on foldables, tablets, and small phones
- Lightweight background services run only while you ask them to
- No account, no tracking, no nags

IP Scanner & Service Watcher is designed to inspect networks and systems **you own or are authorized to test**. It is not a Wi-Fi analyzer, SSID scanner, or nearby-wireless scanner.