> For the complete documentation index, see [llms.txt](https://packetgen.gitbook.io/wiki/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://packetgen.gitbook.io/wiki/protocols/ipv6.md). # IPv6 ## IPv6 Header A IPv6 header consists of a set of fields: ``` 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-------+---------------+---------------------------------------+ |VERSION| Traffic Class | Flow Label | +-------+---------------+-------+---------------+---------------+ | Payload Length | Next Header | Hop-Limit | +-------------------------------+---------------+---------------+ | | | Source Address | | (128 bits) | | | +---------------------------------------------------------------+ | | | Destination Address | | (128 bits) | | | +---------------------------------------------------------------+ ``` * 4-bit protocol version (`IPV6#version`). Attended value is 6 for IPv6, * 8-bit traffic class (\`IPV6#traffic\_class), * 20-bit flow label (`IPv6#flow_label`), * 16-bit payload length (`IPV6#length`), size of IPV6 payload, excluding the header, * 8-bit next header (`IPV6#next`) to indicate upper protocol (6 for TCP, and 17 for UDP by example, but this may also be IPv6 options), * 8-bit hop-limit (`IPV6#hop`), * 128-bit source IPV6 address (`IPV6#src`), * 128-bit destination IPV6 address (`IPV6#dst`), * a body (`IPV6#body`) containing data conveyed by IPv6. A IPV6 header may be built this way: ``` pg> PacketGen::Header::IPv6.new(hop: 32, src: '::1', dst: '::1') => ---- PacketGen::Header::IPv6 ----------------------------------------- Int32 u32: 1610612736 (0x60000000) version: 6 tclass: 0 (0x00) flow_label: 0 (0x00000) Int16 length: 0 (0x0000) Int8 next: 0 (0x00) Int8 hop: 32 (0x20) Addr src: ::1 Addr dst: ::1 ``` ## IPv6 Packet A IPv6 packet may be created this way: ```ruby pkt = PacketGen.gen('IPV6', ttl: 32, src: '10.0.0.1', dst: '20.0.0.1', flag_df: true) pkt.is? 'IPVv' # => true pkt.ipv6 # => PacketGen::Header::IPv6 pkt.ipv6.version # => 6 pkt.ipv6.tclass # => Integer pkt.ipv6.flow_label # => Integer pkt.ipv6.length # => 0 pkt.ipv6.next # => Integer pkt.ipv6.hop # => 32 pkt.ipv6.dst # => '::1' pkt.ipv6.src = '::2' pkt.ipv6.src # => '::2' pkt.body = 'This is a body' pkt.length # => 0 ``` As you can see, `length` is not automatically set to correct value. But it may be set easily with `IPv6#calc_length`. `Packet#calc` may be used too: it automatically call `#calc_sum` and `#calc_length` on all headers responding to them: ``` pg> pkt.calc pg> pkt => -- PacketGen::Packet ------------------------------------------------- ---- PacketGen::Header::IPv6 ----------------------------------------- Int32 u32: 1610612736 (0x60000000) version: 6 tclass: 0 (0x00) flow_label: 0 (0x00000) Int16 length: 14 (0x000e) Int8 next: 0 (0x00) Int8 hop: 32 (0x20) Addr src: ::2 Addr dst: ::1 ---- Body ------------------------------------------------------------ 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 ---------------------------------------------------------------------- 54 68 69 73 20 69 73 20 61 20 62 6f 64 79 This is a body ---------------------------------------------------------------------- ``` ### TCP and UDP headers over IPv6 TCP and UDP headers may be added to a IPv6 packet: ```ruby pg> pkt = PacketGen.gen('IPv6', src: '::1', dst: '::1') pg> pkt.add('TCP', dport: 80, sport: 51234) pg> pkt => -- PacketGen::Packet ------------------------------------------------- ---- PacketGen::Header::IPv6 ----------------------------------------- Int32 u32: 1610612736 (0x60000000) version: 6 tclass: 0 (0x00) flow_label: 0 (0x00000) Int16 length: 0 (0x0000) Int8 next: 6 (0x06) Int8 hop: 64 (0x40) Addr src: ::1 Addr dst: ::1 ---- PacketGen::Header::TCP ------------------------------------------ Int16 sport: 51234 (0xc822) Int16 dport: 80 (0x0050) Int32 seqnum: 6082437 (0x005ccf85) Int32 acknum: 0 (0x00000000) Int16 u16: 20480 (0x5000) data_offset: 5 (0x5) reserved: 0 flags: ......... Int16 window: 0 (0x0000) Int16 checksum: 0 (0x0000) Int16 urg_pointer: 0 (0x0000) Options options: ``` See also .