Fast, Internet-wide scans processing with Rapid7's DAP

Posted on Feb 17

One day of last week I came up with an idea that I had to test against the HTTP headers of millions of servers. To do this quickly, writing practically no code, I’ve used Rapid7’s DAP. It is a nifty little utility that has been the ultimate time-saver for me, and it certainly deserves much more spotlight than it currently has. Plus, hdmoore digs it.

Since the docs are scarce at the moment, I though to contribute with a complete example.

Get all the webservers with a particular header

Get the dataset

First, get the data. does the heavy lifting for us, providing a dataset of GET requests to all IPv4 hosts (so, no vhosts, unfortunately, so we won’t see domains co-located on the same host). Get it:

wget -O the_Internet.gz  # Get the latest one from the site.


Of course, we need to install stuff. Here’s the instructions for Debian/Ubuntu:

sudo aptitude install libgeoip-dev parallel pigz ruby-bundler pv
git clone
cd dap
gem install bundler
bundle install


Now we are ready to go. It’s a long pipeline, that works like this:

pigz -dc the_Internet.gz | \
         pv -t -r -a -l | \
         head -n 300000 | \
         parallel --gnu  --nice 10 --pipe \
         "cd dap; bundle exec bin/dap json  + transform data=base64decode + decode_http_reply data + include data.http_server='Apache' + include data.fancy_header='42' + select ip data data.http_code data.http_raw_headers data.http_server + json"
  • pigz will decompress our dataset quickly (using multiple cores)
  • pv will just let us see what’s going on (printing the progress on the screen)
  • head is nice for getting the pipeline right quickly (processing only the first k sites, for a faster turnaround during debugging)
  • parallel lets us use DAP (a single-core program) on multiple cores (or even multiple hosts!), by splitting the input across a set of workers.
  • dap has is own pipeline to interpret the data, described by its arguments. In particular:
    • Input processing
      • json specifies the input is in JSON, and it needs to be decoded
      • transform data=base64decode specifies that the “data” field in the JSON is BASE64 encoded, and needs decoding
      • decode_http_reply data specifies that the “data” field contains an HTTP reply, which DAP knows how to process to give easier access to its fields.
    • Filtering
      • include data.http_server=’Apache’ will filter out all servers that do not self-report as “Apache” in theirs HTTP headers.
      • include data.fancy_header=’42’ will further filter all the servers without this header
    • Output generation
      • select ip data data.http_code data.http_raw_headers data.http_server specifies we only want these fields in our output, discarding all the rest
      • json tells DAP we want our output as a JSON file.

So, there you go. On my workstation, I can process about 10k sites per second. Pretty sweet, for a few lines of bash.

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