| NetBIOS, NetBEUI, NBF, NBT, NBIPX, SMB, CIFS Networking: NetBIOS to CIFS | ||
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Each SMB frame begins with a standard header. Following a deliminator of "0xFF", there are three bytes "0x53", "0x4d" and "0x42" corresponding to the values "S", "M", "B" which makes identifying SMB frames easier. The three ID bytes are followed by a command byte which is discussed in the section called SMB Command Codes
Table 7. SMB frames (Octets in order transmitted.)
| Field Name | Length | SMB |
|---|---|---|
| Deliminator | 1 | 0xFF |
| ID | 3 | 0x53 "S" |
| 0x4d "M" | ||
| 0x42 "B" | ||
| Command | 1 | 0xNN |
| Error class | 1 | 0xNN |
| Reserved | 1 | reserved |
| Error code | 2 | 0xNN |
| 0xNN | ||
| Flags | 1 | 0xNN |
| Flags 2 / Reserved | 2 | 0xNN |
| 0xNN | ||
| Reserved? 12? | 12 | 0xNN |
| 0xNN | ||
| 0xNN | ||
| 0xNN | ||
| 0xNN | ||
| 0xNN | ||
| 0xNN | ||
| 0xNN | ||
| 0xNN | ||
| 0xNN | ||
| 0xNN | ||
| 0xNN | ||
| authenticated resource identifier / Tree ID | 2 | 0xNN |
| 0xNN | ||
| caller's Process ID | 2 | 0xNN |
| 0xNN | ||
| unathenticated User ID | 2 | 0xNN |
| 0xNN | ||
| Multiplex ID | 2 | 0xNN |
| 0xNN | ||
| count of 16-bit fields Word count | 1 | 0xNN |
| variable no of 16-bit fields byte count | 2 | 0xNN |
| 0xNN | ||
| count of 8-bit fields that follow | 2 | 0xNN |
| 0xNN | ||
| variable number of 8-bit fields | 2 | 0xNN |
| 0xNN |
SMB is very analogous to the NetWare Core Protocol (NCF); there are numerous functions available for accomplishing various tasks. There are very many SMB frames for different functions and all share the same header format; the second field, "command", determines the function and possibly the format of the rest of the frame following the header.
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