ProbeKit: Port Scanning and Network Discovery on Android

Whether you're a network engineer checking a new installation, a sysadmin troubleshooting connectivity, or a home lab enthusiast mapping your own network, having a port scanner in your pocket is genuinely useful. ProbeKit is a free Android app that handles this without needing a laptop.

What ProbeKit Does

ProbeKit is a network discovery and diagnostics tool built for Android. Its core capabilities are:

• Port scanning — scan individual hosts or IP ranges for open ports, with customizable port lists and timeout settings
• Ping — ICMP ping with customisable packet count and interval, displayed as a live graph
• Whois lookup — query domain registration and IP ownership information
• Network info — view your current network's gateway, subnet, DHCP info, and public IP address
• Scan history — results from previous scans are saved so you can compare over time

Port Scanning: Common Use Cases

Port scanning sounds like a hacker tool, but most legitimate uses are mundane: you want to know if a service is actually listening before you spend 20 minutes debugging firewall rules.

Common scenarios:

• Verifying a firewall rule — did opening port 443 actually work? Scan from outside and see.
• Checking a new server — is SSH on port 22 reachable? Is the database port correctly blocked externally?
• Mapping a local network — what devices are active on this subnet? What services are they running?
• Troubleshooting connectivity — is the problem in your application or is the port actually closed?

How Scanning Works

ProbeKit attempts TCP connections to each port in the scan range. If the connection succeeds, the port is open. If it's refused or times out, it's closed or filtered. The distinction matters: a refused connection usually means a firewall or application is actively rejecting it, while a timeout suggests a firewall is silently dropping packets.

Scanning large port ranges takes time. ProbeKit uses concurrent connections to speed things up, but scanning all 65,535 ports is still a minutes-long operation. For most use cases, scanning the top 1,000 ports covers everything you'd realistically encounter.

Responsible Use

Only scan networks you own or have explicit permission to scan. Port scanning third-party hosts without permission may violate their terms of service or local laws. ProbeKit is a tool for your own infrastructure.

Download ProbeKit from Google Play — free, no account required.