Class: PacketFu::IPHeader

IPHeader is a complete IP struct, used in IPPacket. Most traffic on most networks today is IP-based.

For more on IP packets, see www.networksorcery.com/enp/protocol/ip.htm

Header Definition

  Fixnum (4 bits)  :ip_v,     Default: 4
  Fixnum (4 bits)  :ip_hl,    Default: 5
  Int8             :ip_tos,   Default: 0           # TODO: Break out the bits
  Int16            :ip_len,   Default: calculated
  Int16            :ip_id,    Default: calculated  # IRL, hardly random.
  Int16            :ip_frag,  Default: 0           # TODO: Break out the bits
  Int8             :ip_ttl,   Default: 0xff        # Changes per flavor
  Int8             :ip_proto, Default: 0x01        # TCP: 0x06, UDP 0x11, ICMP 0x01
  Int16            :ip_sum,   Default: calculated
  Octets           :ip_src
  Octets           :ip_dst
  String           :body

Note that IPPackets will always be somewhat incorrect upon initalization, and want an IPHeader#recalc() to become correct before a Packet#to_f or Packet#to_w.

Public Class methods

new(args={})

octet_array(addr)

Translate various formats of IPv4 Addresses to an array of digits.

Public Instance methods

ip_calc_id()

Retrieve the IP ID

ip_calc_len()

Calulcate the true length of the packet.

ip_calc_sum()

Calculate the true checksum of the packet. (Yes, this is the long way to do it, but it‘s e-z-2-read for mathtards like me.)

ip_daddr()

Returns a more readable IP destination address.

ip_daddr=(addr)

Sets a more readable IP address.

ip_dst()

Getter for the destination IP address.

ip_dst=(i)

Setter for the destination IP address.

ip_frag()

Getter for the fragmentation ID.

ip_frag=(i)

Setter for the fragmentation ID.

ip_hl()

Getter for the header length (multiply by 4)

ip_hl=(i)

Setter for the header length (divide by 4)

ip_id()

Getter for the identication number.

ip_id=(i)

Setter for the identication number.

ip_len()

Getter for total length.

ip_len=(i)

Setter for total length.

ip_proto()

Getter for the protocol number.

ip_proto=(i)

Setter for the protocol number.

ip_recalc(arg=:all)

Recalculate the calculated IP fields. Valid arguments are:

  :all
  :ip_len
  :ip_sum
  :ip_id

ip_saddr()

Returns a more readable IP source address.

ip_saddr=(addr)

Sets a more readable IP address. If you wants to manipulate individual octets, (eg, for host scanning in one network), it would be better use ip_src.o1 through ip_src.o4 instead.

ip_src()

Getter for the source IP address.

ip_src=(i)

Setter for the source IP address.

ip_sum()

Getter for the checksum.

ip_sum=(i)

Setter for the checksum.

ip_tos()

Getter for the differentiated services

ip_tos=(i)

Setter for the differentiated services