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uint8_t | versionNLength |
| | Version (4 bits) and header length (4 bits). Version=4 for IPv4, length in 32-bit words IPPKT::bVerHdrLen.
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uint8_t | diffServNEcn |
| | Differentiated Services Code Point (6 bits) and Explicit Congestion Notification (2 bits) - used for QoS IPPKT::bTos.
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beuint16_t | totalLength |
| | Total datagram size in bytes including IP header and data payload IPPKT::wLength.
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beuint16_t | identification |
| | Fragment identification field - same for all fragments of a datagram IPPKT::wpktId.
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beuint16_t | flagsNFragmentOffset |
| | Flags (3 bits) and fragment offset (13 bits) - offset in 8-byte units IPPKT::wFlags_Frag.
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uint8_t | timeToLive |
| | Time To Live - typically used as hop count, decremented by each router IPPKT::bTTL.
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uint8_t | protocol |
| | IANA protocol number identifying next-level protocol (TCP=6, UDP=17, ICMP=1) IPPKT::proto.
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beuint16_t | headerChecksum |
| | Header checksum - 16-bit one's complement checksum of IP header only (not data) IPPKT::hCSum.
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beuint32_t | sourceAddress |
| | Source IP address as 4 octets in network byte order IPPKT::ipSrc.
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| |
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beuint32_t | destinationAddress |
| | Destination IP address as 4 octets in network byte order IPPKT::ipDst.
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| |
IP Header Structure (IPv4)
Standard IPv4 packet header as defined in IETF RFC 791 (September 1981) and MIL-STD-1777. This structure represents the 20-byte minimum IP header. IP options, if present, follow this structure and are indicated by a header length value greater than 5.
All multi-byte fields are in network byte order (big-endian) and use the beuint types for automatic endianness handling.
- Note
- The structure is packed to ensure proper alignment with network packet data.
-
Standard header is 20 bytes when no options are present (header length = 5).
-
Maximum header size is 60 bytes (header length = 15) when options are included.
- See also
- IPPKT for the internal representation used within NetBurner stack
