hagelslag

cool scanner <(= w =)>

Why

Starting as a C project, I felt like doing a go version of it.

The hagelslag name came from a friend, well, eating a Hagelslag.

How

hagelslag works by generating all possible IPv4 addresses, checking if they are reserved or not and sending them to workers.

Each worker will wait for addresses coming from a channel, spawn a go routine for each address then start the process of connecting, scanning and saving (when successful).

CLI

-ip
    IP address to start from, without port
-scanner
    Scanner to use (default: http)
-port
    Override the scanners port
-uri    
    MongoDB URI (default: mongodb://localhost:27017)
-only-connect
    Skip scanning, connect and save if successful (default: false)
-rate
    Limit of connections, be careful with this value (default: 1000)

Scanning

If not set to OnlyConnect, the scanner will do the following:

• http: send a GET request.

• minecraft: send a handshake, status request packet.

• veloren: send a init packet, server info packet.

Current behaviour is to read until the response reaches the limit of 15Mb or EOF is encountered.

Saving

Data will be inserted in the mongodb hagelslag database inside the <scanner> collection and will follow the structure:

mongodb has a limit of 16Mb for a document, if a response exceeds 15Mb, the json/html that will be saved will be malformed, validate the data before using it.

data field can be a string (for html or malformed response) or a json object.

{
    "_id": "<address>",
    "latency": 0,
    "data": ""
}

TODO/Ideas

• Maybe an interface for both DialTCP and DialUDP.

• Improve logging.

• At high rates, DB connection errors out, maybe using bulk write can solve this.

• Maybe add bedrocks servers to the Minecraft scanner.

• Remove this weird virus that keeps adding Frieren in the code.