Class: PacketFu::Utils

Inherits:
Object
  • Object
show all
Defined in:
lib/packetfu/utils.rb

Overview

Utils is a collection of various and sundry network utilities that are useful for packet manipulation.

Class Method Summary collapse

Class Method Details

.arp(target_ip, args = {}) ⇒ Object

Returns the MAC address of an IP address, or nil if it's not responsive to arp. Takes a dotted-octect notation of the target IP address, as well as a number of parameters:

Parameters

:iface

Interface. Defaults to "eth0"
 :eth_saddr
  Source MAC address. Defaults to "00:00:00:00:00:00".
 :ip_saddr
  Source IP address. Defaults to "0.0.0.0"
 :flavor
  The flavor of the ARP request. Defaults to :none.
 :timeout
  Timeout in seconds. Defaults to 3.

=== Example
  PacketFu::Utils::arp("192.168.1.1") #=> "00:18:39:01:33:70"
  PacketFu::Utils::arp("192.168.1.1", :iface => "wlan2", :timeout => 5, :flavor => :hp_deskjet)

=== Warning

It goes without saying, spewing forged ARP packets on your network is a great way to really
irritate your co-workers.

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# File 'lib/packetfu/utils.rb', line 35

def self.arp(target_ip,args={})
  iface = args[:iface] || :eth0
  args[:config] ||= whoami?(:iface => iface)
  arp_pkt = PacketFu::ARPPacket.new(:flavor => (args[:flavor] || :none), :config => args[:config])
  arp_pkt.eth_daddr = "ff:ff:ff:ff:ff:ff"
  arp_pkt.arp_daddr_mac = "00:00:00:00:00:00"
  arp_pkt.arp_daddr_ip = target_ip
  # Stick the Capture object in its own thread.
  cap_thread = Thread.new do
    target_mac = nil
    cap = PacketFu::Capture.new(:iface => iface, :start => true, 
    :filter => "arp src #{target_ip} and ether dst #{arp_pkt.eth_saddr}")
    arp_pkt.to_w(iface) # Shorthand for sending single packets to the default interface.
    timeout = 0
    while target_mac.nil? && timeout <= (args[:timeout] || 3)
      if cap.save > 0
        arp_response = PacketFu::Packet.parse(cap.array[0])
        target_mac = arp_response.arp_saddr_mac if arp_response.arp_saddr_ip = target_ip
      end
      timeout += 0.1
      sleep 0.1 # Check for a response ten times per second.
    end
    target_mac
  end # cap_thread
  cap_thread.value
end

.default_intObject

Determine the default routeable interface


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# File 'lib/packetfu/utils.rb', line 166

def self.default_int
  ip = default_ip

  NetworkInterface.interfaces.each do |interface|
    NetworkInterface.addresses(interface).values.each do |addresses|
      addresses.each do |address|
        next if address["addr"].nil?
        return interface if address["addr"] == ip
      end
    end
  end

  # Fall back to libpcap as last resort
  return Pcap.lookupdev
end

.default_ipObject

Determine the default ip address


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# File 'lib/packetfu/utils.rb', line 152

def self.default_ip
  begin
    orig, Socket.do_not_reverse_lookup = Socket.do_not_reverse_lookup, true  # turn off reverse DNS resolution temporarily
 
	UDPSocket.open do |s|
			s.connect rand_routable_daddr.to_s, rand_port
			s.addr.last
	end
  ensure
	Socket.do_not_reverse_lookup = orig
  end
end

.ifconfig(iface = 'eth0') ⇒ Object

Handles ifconfig for various (okay, two) platforms. Will have Windows done shortly.

Takes an argument (either string or symbol) of the interface to look up, and returns a hash which contains at least the :iface element, and if configured, these additional elements:

:eth_saddr  # A human readable MAC address
:eth_src    # A packed MAC address
:ip_saddr   # A dotted-quad string IPv4 address
:ip_src     # A packed IPv4 address
:ip4_obj    # An IPAddr object with bitmask
:ip6_saddr  # A colon-delimited hex IPv6 address, with bitmask
:ip6_obj    # An IPAddr object with bitmask

Example

PacketFu::Utils.ifconfig :wlan0 # Not associated yet
#=> {:eth_saddr=>"00:1d:e0:73:9d:ff", :eth_src=>"\000\035\340s\235\377", :iface=>"wlan0"}
PacketFu::Utils.ifconfig("eth0") # Takes 'eth0' as default
#=> {:eth_saddr=>"00:1c:23:35:70:3b", :eth_src=>"\000\034#5p;", :ip_saddr=>"10.10.10.9", :ip4_obj=>#<IPAddr: IPv4:10.10.10.0/255.255.254.0>, :ip_src=>"\n\n\n\t", :iface=>"eth0", :ip6_saddr=>"fe80::21c:23ff:fe35:703b/64", :ip6_obj=>#<IPAddr: IPv6:fe80:0000:0000:0000:0000:0000:0000:0000/ffff:ffff:ffff:ffff:0000:0000:0000:0000>}  
PacketFu::Utils.ifconfig :lo
#=> {:ip_saddr=>"127.0.0.1", :ip4_obj=>#<IPAddr: IPv4:127.0.0.0/255.0.0.0>, :ip_src=>"\177\000\000\001", :iface=>"lo", :ip6_saddr=>"::1/128", :ip6_obj=>#<IPAddr: IPv6:0000:0000:0000:0000:0000:0000:0000:0001/ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff>}

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# File 'lib/packetfu/utils.rb', line 204

def self.ifconfig(iface='eth0')
  ret = {}
  iface = iface.to_s.scan(/[0-9A-Za-z]/).join # Sanitizing input, no spaces, semicolons, etc.
  case RUBY_PLATFORM
  when /linux/i
    ifconfig_data = %x[ifconfig #{iface}]
    if ifconfig_data =~ /#{iface}/i
      ifconfig_data = ifconfig_data.split(/[\s]*\n[\s]*/)
    else
      raise ArgumentError, "Cannot ifconfig #{iface}"
    end
    real_iface = ifconfig_data.first
    ret[:iface] = real_iface.split.first.downcase
    if real_iface =~ /[\s]HWaddr[\s]+([0-9a-fA-F:]{17})/i
      ret[:eth_saddr] = $1.downcase
      ret[:eth_src] = EthHeader.mac2str(ret[:eth_saddr])
    end
    ifconfig_data.each do |s|
      case s
      when /inet addr:[\s]*([0-9]+\.[0-9]+\.[0-9]+\.[0-9]+)(.*Mask:([0-9]+\.[0-9]+\.[0-9]+\.[0-9]+))?/i
        ret[:ip_saddr] = $1
        ret[:ip_src] = [IPAddr.new($1).to_i].pack("N")
        ret[:ip4_obj] = IPAddr.new($1)
        ret[:ip4_obj] = ret[:ip4_obj].mask($3) if $3
      when /inet6 addr:[\s]*([0-9a-fA-F:\x2f]+)/
        ret[:ip6_saddr] = $1
        ret[:ip6_obj] = IPAddr.new($1)
      end
    end # linux
  when /darwin/i
    ifconfig_data = %x[ifconfig #{iface}]
    if ifconfig_data =~ /#{iface}/i
      ifconfig_data = ifconfig_data.split(/[\s]*\n[\s]*/)
    else
      raise ArgumentError, "Cannot ifconfig #{iface}"
    end
    real_iface = ifconfig_data.first
    ret[:iface] = real_iface.split(':')[0]
    ifconfig_data.each do |s|
      case s
      when /ether[\s]([0-9a-fA-F:]{17})/i
        ret[:eth_saddr] = $1
        ret[:eth_src] = EthHeader.mac2str(ret[:eth_saddr])
      when /inet[\s]*([0-9]+\.[0-9]+\.[0-9]+\.[0-9]+)(.*Mask:([0-9]+\.[0-9]+\.[0-9]+\.[0-9]+))?/i
        ret[:ip_saddr] = $1
        ret[:ip_src] = [IPAddr.new($1).to_i].pack("N")
        ret[:ip4_obj] = IPAddr.new($1)
        ret[:ip4_obj] = ret[:ip4_obj].mask($3) if $3
      when /inet6[\s]*([0-9a-fA-F:\x2f]+)/
        ret[:ip6_saddr] = $1
        ret[:ip6_obj] = IPAddr.new($1)
      end
    end # darwin
  end # RUBY_PLATFORM
  ret
end

.rand_portObject

A helper for getting a random port number


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# File 'lib/packetfu/utils.rb', line 69

def self.rand_port
  rand(0xffff-1024)+1024
end

.rand_routable_daddrObject

Since 177/8 is IANA reserved (for now), this network should be handled by your default gateway and default interface.


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# File 'lib/packetfu/utils.rb', line 64

def self.rand_routable_daddr
  IPAddr.new((rand(16777216) + 2969567232), Socket::AF_INET)
end

.whoami?(args = {}) ⇒ Boolean

Discovers the local IP and Ethernet address, which is useful for writing packets you expect to get a response to. Note, this is a noisy operation; a UDP packet is generated and dropped on to the default (or named) interface, and then captured (which means you need to be root to do this).

whoami? returns a hash of :eth_saddr, :eth_src, :ip_saddr, :ip_src, :ip_src_bin, :eth_dst, and :eth_daddr (the last two are usually suitable for a gateway mac address). It's most useful as an argument to PacketFu::Config.new, or as an argument to the many Packet constructors.

Note that if you have multiple interfaces with the same route (such as when wlan0 and eth0 are associated to the same network), the “first” one according to Pcap.lookupdev will be used, regardless of which :iface you pick.

Parameters

:iface => "eth0"
 An interface to listen for packets on. Note that since we rely on the OS to send the probe packet,
 you will need to specify a target which will use this interface.
:target => "1.2.3.4"
 A target IP address. By default, a packet will be sent to a random address in the 177/8 network.

Returns:

  • (Boolean)

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# File 'lib/packetfu/utils.rb', line 94

def self.whoami?(args={})
  unless args.kind_of? Hash
    raise ArgumentError, "Argument to `whoami?' must be a Hash"
  end
  if args[:iface].to_s =~ /^lo/ # Linux loopback more or less. Need a switch for windows loopback, too.
    dst_host = "127.0.0.1"
  else
    dst_host = (args[:target] || rand_routable_daddr.to_s)
  end

  dst_port = rand_port
  msg = "PacketFu whoami? packet #{(Time.now.to_i + rand(0xffffff)+1)}"
  iface = (args[:iface] || ENV['IFACE'] || default_int || :lo ).to_s
  cap = PacketFu::Capture.new(:iface => iface, :promisc => false, :start => true, :filter => "udp and dst host #{dst_host} and dst port #{dst_port}")
  udp_sock = UDPSocket.new
  udp_sock.send(msg,0,dst_host,dst_port)
  udp_sock = nil

  my_data = nil

  begin
    Timeout::timeout(1) {
      pkt = nil
      
      while pkt.nil?
        raw_pkt = cap.next
        next if raw_pkt.nil?

        pkt = Packet.parse(raw_pkt)
        
        if pkt.payload == msg

          my_data =	{
            :iface => (args[:iface] || ENV['IFACE'] || default_int || "lo").to_s,
            :pcapfile => args[:pcapfile] || "/tmp/out.pcap",
            :eth_saddr => pkt.eth_saddr,
            :eth_src => pkt.eth_src.to_s,
            :ip_saddr => pkt.ip_saddr,
            :ip_src => pkt.ip_src,
            :ip_src_bin => [pkt.ip_src].pack("N"),
            :eth_dst => pkt.eth_dst.to_s,
            :eth_daddr => pkt.eth_daddr
          }

        else raise SecurityError, 
          "whoami() packet doesn't match sent data. Something fishy's going on."
        end

      end
    }
  rescue Timeout::Error
    raise SocketError, "Didn't receive the whoami() packet, can't automatically configure."
  end

  my_data
end