Library packet

Facilities for manipulating raw packets.

Author:

• Marek Majkowski <majek04+nse@gmail.com>

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

Source: https://svn.nmap.org/nmap/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.

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.

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.

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.

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.

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 destination 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 destination 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 (beginning 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.