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Library packet

Facilities for manipulating raw packets.

Author:
Marek Majkowski <majek04+nse@gmail.com>

Copyright© Same as Nmap--See http://nmap.org/book/man-legal.html

Source: http://nmap.org/svn/nselib/packet.lua

Functions

Frame:build_ether_frame (mac_dst, mac_src, ether_type, packet)

Build an Ethernet frame.
Frame:ether_parse (frame)

Parse an Ethernet frame.
in_cksum (b)

Calculate a standard Internet checksum.
ip6tobin (str)

Convert an IPv6 address string (like "fe80:21::1") to a raw string 16 bytes long (big-endian).
iptobin (str)

Convert a dotted-quad IP address string (like "1.2.3.4") to a raw string four bytes long.
ipv6_hdr_pack_tc_fl (ip6_tc, ip6_fl)

Convert Version, Traffic Class and Flow Label to a 4-byte string.
mac_to_lladdr (mac)

Generate the link-local IPv6 address from the MAC address.
mactobin (str)

Convert a MAC address string (like "00:23:ae:5d:3b:10") to a raw six-byte long.
numtostr16 (num)

Get a 2-byte string from a number. (big-endian)
numtostr32 (num)

Get a 4-byte string from a number. (big-endian)
numtostr8 (num)

Get a 1-byte string from a number.
Packet:build_icmp_echo_request (id, seq, data, mac_src, mac_dst, ip_bin_src, ip_bin_dst, dsf)

Build an ICMP Echo Request frame.
Packet:build_icmp_header (icmp_type, icmp_code, icmp_payload, ip_bin_src, ip_bin_dst)

Build an ICMP header.
Packet:build_icmpv6_echo_request (id, sequence, data, mac_src, mac_dst, ip_bin_src, ip_bin_dst, tc, fl, hop_limit)

Build an ICMPv6 Echo Request frame.
Packet:build_icmpv6_header (icmpv6_type, icmpv6_code, icmpv6_payload, ip_bin_src, ip_bin_dst)

Build an ICMPv6 header.
Packet:build_ip_packet (src, dst, payload, dsf, id, flags, off, ttl, proto)

Build an IPv4 packet.
Packet:build_ipv6_packet (src, dst, nx_hdr, payload, h_limit, t_class, f_label, dsr)

Build an IPv6 packet.
Packet:count_ipv6_pseudoheader_cksum ()

Count IPv6 checksum.
Packet:icmp_parse (force_continue)

Parse an ICMP packet header.
Packet:icmp_tostring ()

Get a short string representation of the ICMP header.
Packet:icmpv6_parse (force_continue)

Parse an ICMPv6 packet header.
Packet:ip6_parse (force_continue)

Parse an IPv6 packet header.
Packet:ip6_set_plen (plen)

Set the payload length field.
Packet:ip_count_checksum ()

Count checksum for packet and save it.
Packet:ip_parse (force_continue)

Parse an IP packet header.
Packet:ip_set_bin_dst (binip)

Set the destination IP address.
Packet:ip_set_bin_src (binip)

Set the source IP address.
Packet:ip_set_checksum (checksum)

Set the checksum.
Packet:ip_set_hl (len)

Set the header length field.
Packet:ip_set_id (id)

Set the packet identification field.
Packet:ip_set_len (len)

Set the packet length field.
Packet:ip_set_options (ipoptions)

Set the IP options field (and move the data, count new length, etc.).
Packet:ip_set_ttl (ttl)

Set the TTL.
Packet:ip_tostring ()

Get a short string representation of the IP header.
Packet:ipv6_ext_header_parse (force_continue)

Pare an IPv6 extension header. Just jump over it at the moment.
Packet:ipv6_is_extension_header (nhdr)

Return true if and only if the next header is an known extension header.
Packet:new (packet, packet_len, force_continue)

Create a new Packet object.
Packet:parse_options (offset, length)

Parse IP/TCP options into a table.
Packet:raw (index, length)

Return part of the packet contents as a byte string.
Packet:set_icmp6_cksum (check_sum)

Set ICMPv6 checksum.
Packet:set_icmpv6_option (opt_type, msg)

Set an ICMPv6 option message.
Packet:set_u16 (index, num)

Set a 16-bit integer at a 0-based byte offset in the packet. (big-endian).
Packet:set_u32 (index, num)

Set a 32-bit integer at a 0-based byte offset in the packet. (big-endian).
Packet:set_u8 (index, num)

Set an 8-bit integer at a 0-based byte offset in the packet. (big-endian).
Packet:tcp_count_checksum ()

Count and save the TCP checksum field.
Packet:tcp_lookup_link ()

Map an MTU to a link type string. Stolen from p0f.
Packet:tcp_parse (force_continue)

Parse a TCP packet header.
Packet:tcp_parse_options ()

Parse options for TCP header.
Packet:tcp_set_checksum (checksum)

Set the TCP checksum field.
Packet:tcp_set_dport (port)

Set the TCP destination port.
Packet:tcp_set_flags (new_flags)

Set the TCP flags field (like SYN, ACK, RST).
Packet:tcp_set_seq (new_seq)

Set the TCP sequence field.
Packet:tcp_set_sport (port)

Set the TCP source port.
Packet:tcp_set_urp (urg_ptr)

Set the urgent pointer field.
Packet:tcp_tostring ()

Get a short string representation of the TCP packet.
Packet:tostring ()

Get a short string representation of the packet.
Packet:u16 (index)

Get a 16-bit integer at a 0-based byte offset in the packet.
Packet:u32 (index)

Get a 32-bit integer at a 0-based byte offset in the packet.
Packet:u8 (index)

Get an 8-bit integer at a 0-based byte offset in the packet.
Packet:udp_count_checksum ()

Count and save the UDP checksum field.
Packet:udp_parse (force_continue)

Parse a UDP packet header.
Packet:udp_set_checksum (checksum)

Set the UDP checksum field.
Packet:udp_set_dport (port)

Set the UDP destination port.
Packet:udp_set_length (len)

Set the UDP payload length.
Packet:udp_set_sport (port)

Set the UDP source port.
Packet:udp_tostring ()

Get a short string representation of the UDP packet.
set_u16 (b, i, num)

Set a 16-bit integer at a 0-based byte offset in a byte string (big-endian).
set_u32 (b, i, num)

Set a 32-bit integer at a 0-based byte offset in a byte string (big-endian).
set_u8 (b, i, num)

Set an 8-bit integer at a 0-based byte offset in a byte string (big-endian).
toip (raw_ip_addr)

Convert a four-byte raw string to a dotted-quad IP address string.
toipv6 (raw_ipv6_addr)

Convert a 16-byte raw string to an IPv6 address string.
u16 (b, i)

Get a 16-bit integer at a 0-based byte offset in a byte string.
u32 (b, i)

Get a 32-bit integer at a 0-based byte offset in a byte string.
u8 (b, i)

Get an 8-bit integer at a 0-based byte offset in a byte string.


Functions

Frame:build_ether_frame (mac_dst, mac_src, ether_type, packet)

Build an Ethernet frame.

Parameters

  • mac_dst: six-byte string of the destination MAC address.
  • mac_src: six-byte string of the source MAC address.
  • ether_type: two-byte string of the type.
  • packet: string of the payload.

Return value:

frame string of the Ether frame.
Frame:ether_parse (frame)

Parse an Ethernet frame.

Parameters

  • frame: string of the Ether frame.

Return values:

  1. mac_dst six-byte string of the destination MAC address.
  2. mac_src six-byte string of the source MAC address.
  3. packet string of the payload.
in_cksum (b)

Calculate a standard Internet checksum.

Parameters

  • b: Data to checksum.

Return value:

Checksum.
ip6tobin (str)

Convert an IPv6 address string (like "fe80:21::1") to a raw string 16 bytes long (big-endian).

Parameters

  • str: IPv6 address string.

Return value:

16-byte string.
iptobin (str)

Convert a dotted-quad IP address string (like "1.2.3.4") to a raw string four bytes long.

Parameters

  • str: IP address string.

Return value:

Four-byte string.
ipv6_hdr_pack_tc_fl (ip6_tc, ip6_fl)

Convert Version, Traffic Class and Flow Label to a 4-byte string.

Parameters

  • ip6_tc: Number stands for Traffic Class.
  • ip6_fl: Number stands for Flow Label.

Return value:

The first four-byte string of an IPv6 header.
mac_to_lladdr (mac)

Generate the link-local IPv6 address from the MAC address.

Parameters

  • mac: MAC address string.

Return value:

Link-local IPv6 address string.
mactobin (str)

Convert a MAC address string (like "00:23:ae:5d:3b:10") to a raw six-byte long.

Parameters

  • str: MAC address string.

Return value:

Six-byte string.
numtostr16 (num)

Get a 2-byte string from a number. (big-endian)

Parameters

  • num: A number.
numtostr32 (num)

Get a 4-byte string from a number. (big-endian)

Parameters

  • num: A number.
numtostr8 (num)

Get a 1-byte string from a number.

Parameters

  • num: A number.
Packet:build_icmp_echo_request (id, seq, data, mac_src, mac_dst, ip_bin_src, ip_bin_dst, dsf)

Build an ICMP Echo Request frame.

Parameters

  • id: integer that represents Echo ID.
  • seq: integer that represents Echo sequence.
  • data: string of Echo data.
  • mac_src: six-byte string of source MAC address.
  • mac_dst: sis-byte string of destination MAC address.
  • ip_bin_src: 16-byte string of source IPv6 address.
  • ip_bin_dst: 16-byte string of destinatiion IPv6 address.
  • dsf: integer that represents differentiated services field.
Packet:build_icmp_header (icmp_type, icmp_code, icmp_payload, ip_bin_src, ip_bin_dst)

Build an ICMP header.

Parameters

  • icmp_type: integer that represent ICMPv6 type.
  • icmp_code: integer that represent ICMPv6 code.
  • icmp_payload: string of the payload
  • ip_bin_src: 16-byte string of the source IPv6 address.
  • ip_bin_dst: 16-byte string of the destination IPv6 address.
Packet:build_icmpv6_echo_request (id, sequence, data, mac_src, mac_dst, ip_bin_src, ip_bin_dst, tc, fl, hop_limit)

Build an ICMPv6 Echo Request frame.

Parameters

  • id: integer that represents Echo ID.
  • sequence: integer that represents Echo sequence.
  • data: string of Echo data.
  • mac_src: six-byte string of source MAC address.
  • mac_dst: sis-byte string of destination MAC address.
  • ip_bin_src: 16-byte string of source IPv6 address.
  • ip_bin_dst: 16-byte string of destinatiion IPv6 address.
  • tc: integer that represents traffic class of IPv6 packet.
  • fl: integer that represents flow label of IPv6 packet.
  • hop_limit:
Packet:build_icmpv6_header (icmpv6_type, icmpv6_code, icmpv6_payload, ip_bin_src, ip_bin_dst)

Build an ICMPv6 header.

Parameters

  • icmpv6_type: integer that represent ICMPv6 type.
  • icmpv6_code: integer that represent ICMPv6 code.
  • icmpv6_payload: string of the payload
  • ip_bin_src: 16-byte string of the source IPv6 address.
  • ip_bin_dst: 16-byte string of the destination IPv6 address.
Packet:build_ip_packet (src, dst, payload, dsf, id, flags, off, ttl, proto)

Build an IPv4 packet.

Parameters

  • src: 4-byte string of the source IP address.
  • dst: 4-byte string of the destination IP address.
  • payload: string containing the IP payload
  • dsf: byte that represents the differentiated services field
  • id: integer that represents the IP identification
  • flags: integer that represents the IP flags
  • off: integer that represents the IP offset
  • ttl: integer that represent the IP time to live
  • proto: integer that represents the IP protocol
Packet:build_ipv6_packet (src, dst, nx_hdr, payload, h_limit, t_class, f_label, dsr)

Build an IPv6 packet.

Parameters

  • src: 16-byte string of the source IPv6 address.
  • dst:
  • nx_hdr: integer that represents next header.
  • payload:
  • h_limit: integer that represents hop limit.
  • t_class: integer that represents traffic class.
  • f_label: integer that represents flow label.
  • dsr: 16-byte string of the destination IPv6 address.
Packet:count_ipv6_pseudoheader_cksum ()

Count IPv6 checksum.

Return value:

the checksum.
Packet:icmp_parse (force_continue)

Parse an ICMP packet header.

Parameters

  • force_continue: Ignored.

Return value:

Whether the parsing succeeded.
Packet:icmp_tostring ()

Get a short string representation of the ICMP header.

Return value:

A string representation of the ICMP header.
Packet:icmpv6_parse (force_continue)

Parse an ICMPv6 packet header.

Parameters

  • force_continue: Ignored.

Return value:

Whether the parsing succeeded.
Packet:ip6_parse (force_continue)

Parse an IPv6 packet header.

Parameters

  • force_continue: Ignored.

Return value:

Whether the parsing succeeded.
Packet:ip6_set_plen (plen)

Set the payload length field.

Parameters

  • plen: Payload length.
Packet:ip_count_checksum ()

Count checksum for packet and save it.

Packet:ip_parse (force_continue)

Parse an IP packet header.

Parameters

  • force_continue: Ignored.

Return value:

Whether the parsing succeeded.
Packet:ip_set_bin_dst (binip)

Set the destination IP address.

Parameters

  • binip: The destination IP address as a byte string.
Packet:ip_set_bin_src (binip)

Set the source IP address.

Parameters

  • binip: The source IP address as a byte string.
Packet:ip_set_checksum (checksum)

Set the checksum.

Parameters

  • checksum: Checksum.
Packet:ip_set_hl (len)

Set the header length field.

Parameters

  • len:
Packet:ip_set_id (id)

Set the packet identification field.

Parameters

  • id: packet ID.
Packet:ip_set_len (len)

Set the packet length field.

Parameters

  • len: Packet length.
Packet:ip_set_options (ipoptions)

Set the IP options field (and move the data, count new length, etc.).

Parameters

  • ipoptions: IP options.
Packet:ip_set_ttl (ttl)

Set the TTL.

Parameters

  • ttl: TTL.
Packet:ip_tostring ()

Get a short string representation of the IP header.

Return value:

A string representation of the IP header.
Packet:ipv6_ext_header_parse (force_continue)

Pare an IPv6 extension header. Just jump over it at the moment.

Parameters

  • force_continue: Ignored.

Return value:

Whether the parsing succeeded.
Packet:ipv6_is_extension_header (nhdr)

Return true if and only if the next header is an known extension header.

Parameters

  • nhdr: Next header.
Packet:new (packet, packet_len, force_continue)

Create a new Packet object.

Parameters

  • packet: Binary string with packet data.
  • packet_len: Packet length. It could be more than #packet.
  • force_continue: whether an error in parsing headers should be fatal or not. This is especially useful when parsing ICMP packets, where a small ICMP payload could be a TCP header. The problem is that parsing this payload normally would fail because the TCP header is too small.

Return value:

A new Packet.
Packet:parse_options (offset, length)

Parse IP/TCP options into a table.

Parameters

  • offset: Offset at which options start.
  • length: Length of options.

Return value:

Table of options.
Packet:raw (index, length)

Return part of the packet contents as a byte string.

Parameters

  • index: The beginning of the part of the packet to extract. The index is 0-based. If omitted the default value is 0 (begining of the string)
  • length: The length of the part of the packet to extract. If omitted the remaining contents from index to the end of the string are returned.

Return value:

A string.
Packet:set_icmp6_cksum (check_sum)

Set ICMPv6 checksum.

Parameters

  • check_sum:
Packet:set_icmpv6_option (opt_type, msg)

Set an ICMPv6 option message.

Parameters

  • opt_type:
  • msg:
Packet:set_u16 (index, num)

Set a 16-bit integer at a 0-based byte offset in the packet. (big-endian).

Parameters

  • index: Offset.
  • num: Integer to store.
Packet:set_u32 (index, num)

Set a 32-bit integer at a 0-based byte offset in the packet. (big-endian).

Parameters

  • index: Offset.
  • num: Integer to store.
Packet:set_u8 (index, num)

Set an 8-bit integer at a 0-based byte offset in the packet. (big-endian).

Parameters

  • index: Offset.
  • num: Integer to store.
Packet:tcp_count_checksum ()

Count and save the TCP checksum field.

Packet:tcp_lookup_link ()

Map an MTU to a link type string. Stolen from p0f.

Return value:

A string describing the link type.
Packet:tcp_parse (force_continue)

Parse a TCP packet header.

Parameters

  • force_continue: Whether a short packet causes parsing to fail.

Return value:

Whether the parsing succeeded.
Packet:tcp_parse_options ()

Parse options for TCP header.

Packet:tcp_set_checksum (checksum)

Set the TCP checksum field.

Parameters

  • checksum: Checksum.
Packet:tcp_set_dport (port)

Set the TCP destination port.

Parameters

  • port: Destination port.
Packet:tcp_set_flags (new_flags)

Set the TCP flags field (like SYN, ACK, RST).

Parameters

  • new_flags: Flags, represented as an 8-bit number.
Packet:tcp_set_seq (new_seq)

Set the TCP sequence field.

Parameters

  • new_seq: Sequence.
Packet:tcp_set_sport (port)

Set the TCP source port.

Parameters

  • port: Source port.
Packet:tcp_set_urp (urg_ptr)

Set the urgent pointer field.

Parameters

  • urg_ptr: Urgent pointer.
Packet:tcp_tostring ()

Get a short string representation of the TCP packet.

Return value:

A string representation of the TCP header.
Packet:tostring ()

Get a short string representation of the packet.

Return value:

A string representation of the packet.
Packet:u16 (index)

Get a 16-bit integer at a 0-based byte offset in the packet.

Parameters

  • index: Offset.

Return value:

A 16-bit integer.
Packet:u32 (index)

Get a 32-bit integer at a 0-based byte offset in the packet.

Parameters

  • index: Offset.

Return value:

An 32-bit integer.
Packet:u8 (index)

Get an 8-bit integer at a 0-based byte offset in the packet.

Parameters

  • index: Offset.

Return value:

An 8-bit integer.
Packet:udp_count_checksum ()

Count and save the UDP checksum field.

Packet:udp_parse (force_continue)

Parse a UDP packet header.

Parameters

  • force_continue: Whether a short packet causes parsing to fail.

Return value:

Whether the parsing succeeded.
Packet:udp_set_checksum (checksum)

Set the UDP checksum field.

Parameters

  • checksum: Checksum.
Packet:udp_set_dport (port)

Set the UDP destination port.

Parameters

  • port: Destination port.
Packet:udp_set_length (len)

Set the UDP payload length.

Parameters

  • len: UDP payload length.
Packet:udp_set_sport (port)

Set the UDP source port.

Parameters

  • port: Source port.
Packet:udp_tostring ()

Get a short string representation of the UDP packet.

Return value:

A string representation of the UDP header.
set_u16 (b, i, num)

Set a 16-bit integer at a 0-based byte offset in a byte string (big-endian).

Parameters

  • b: A byte string.
  • i: Offset.
  • num: Integer to store.
set_u32 (b, i, num)

Set a 32-bit integer at a 0-based byte offset in a byte string (big-endian).

Parameters

  • b: A byte string.
  • i: Offset.
  • num: Integer to store.
set_u8 (b, i, num)

Set an 8-bit integer at a 0-based byte offset in a byte string (big-endian).

Parameters

  • b: A byte string.
  • i: Offset.
  • num: Integer to store.
toip (raw_ip_addr)

Convert a four-byte raw string to a dotted-quad IP address string.

Parameters

  • raw_ip_addr: Four-byte string.

Return value:

IP address string.
toipv6 (raw_ipv6_addr)

Convert a 16-byte raw string to an IPv6 address string.

Parameters

  • raw_ipv6_addr: 16-byte string.

Return value:

IPv6 address string.
u16 (b, i)

Get a 16-bit integer at a 0-based byte offset in a byte string.

Parameters

  • b: A byte string.
  • i: Offset.

Return value:

A 16-bit integer.
u32 (b, i)

Get a 32-bit integer at a 0-based byte offset in a byte string.

Parameters

  • b: A byte string.
  • i: Offset.

Return value:

A 32-bit integer.
u8 (b, i)

Get an 8-bit integer at a 0-based byte offset in a byte string.

Parameters

  • b: A byte string.
  • i: Offset.

Return value:

An 8-bit integer.

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