It was only a matter of time till the first queries for tools like https://www.shodan.io to search for Home Assistant instances showed up.
To get an idea about how your Home Assistant instance looks like for network scanner, you can use
nmap tool is already available if you are using the nmap device tracker.
$ nmap -sV -p 8123 --script=http-title,http-headers 192.168.1.3 Starting Nmap 7.12 ( https://nmap.org ) at 2016-10-06 10:01 CEST Nmap scan report for 192.168.1.3 (192.168.1.3) Host is up (0.00011s latency). PORT STATE SERVICE VERSION 8123/tcp open http CherryPy wsgiserver | http-headers: | Content-Type: text/html; charset=utf-8 | Content-Length: 4309 | Connection: close | Date: Thu, 06 Oct 2016 08:01:31 GMT | Server: Home Assistant | |_ (Request type: GET) |_http-server-header: Home Assistant |_http-title: Home Assistant Service detection performed. Please report any incorrect results at https://nmap.org/submit/ . Nmap done: 1 IP address (1 host up) scanned in 6.70 seconds