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3. protocols/tcp
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5. Zen

67 ../../protocols/tcp.rst:225
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — the first byte indicates the `type` of the option. 50/10000 · 50
68 ../../protocols/tcp.rst:226
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — the second byte indicates the total length of the option (including the first two bytes) in bytes 97/10000 · 97
69 ../../protocols/tcp.rst:227
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — the last bytes are specific for each type of option 51/10000 · 51
70 ../../protocols/tcp.rst:229
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — :rfc:`793` defines the Maximum Segment Size (MSS) TCP option that must be understood by all TCP implementations. This option (type 2) has a length of 4 bytes and contains a 16 bits word that indicates the MSS supported by the sender of the `SYN` segment. The MSS option can only be used in TCP segments having the `SYN` flag set. 329/10000 · 329
71 ../../protocols/tcp.rst:231
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — :rfc:`793` also defines two special options that must be supported by all TCP implementations. The first option is `End of option`. It is encoded as a single byte having value `0x00` and can be used to ensure that the TCP header extension ends on a 32 bits boundary. The `No-Operation` option, encoded as a single byte having value `0x01`, can be used when the TCP header extension contains several TCP options that should be aligned on 32 bit boundaries. All other options [#ftcpoptions]_ are encoded using the TLV format. 523/10000 · 523
72 ../../protocols/tcp.rst:233
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The robustness principle 24/10000 · 24
73 ../../protocols/tcp.rst:235
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The handling of the TCP options by TCP implementations is one of the many applications of the `robustness principle` which is usually attributed to `Jon Postel`_ and is often quoted as `"Be liberal in what you accept, and conservative in what you send"` :rfc:`1122`. 266/10000 · 266
74 ../../protocols/tcp.rst:237
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Concerning the TCP options, the robustness principle implies that a TCP implementation should be able to accept TCP options that it does not understand, in particular in received `SYN` segments, and that it should be able to parse any received segment without crashing, even if the segment contains an unknown TCP option. Furthermore, a server should not send in the `SYN+ACK` segment or later, options that have not been proposed by the client in the `SYN` segment. 466/10000 · 466
75 ../../protocols/tcp.rst:243
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — TCP reliable data transfer 26/10000 · 26
76 ../../protocols/tcp.rst:245
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The original TCP data transfer mechanisms were defined in :rfc:`793`. Based on the experience of using TCP on the growing global Internet, this part of the TCP specification has been updated and improved several times, always while preserving the backward compatibility with older TCP implementations. In this section, we review the main data transfer mechanisms used by TCP. 375/10000 · 375
77 ../../protocols/tcp.rst:247
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — TCP is a window-based transport protocol that provides a bi-directional byte stream service. This has several implications on the fields of the TCP header and the mechanisms used by TCP. The three fields of the TCP header are : 227/10000 · 227
78 ../../protocols/tcp.rst:249
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — `sequence number`. TCP uses a 32 bits sequence number. The `sequence number` placed in the header of a TCP segment containing data is the sequence number of the first byte of the payload of the TCP segment. 206/10000 · 206
79 ../../protocols/tcp.rst:250
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — `acknowledgment number`. TCP uses cumulative positive acknowledgments. Each TCP segment contains the `sequence number` of the next byte that the sender of the acknowledgment expects to receive from the remote host. In theory, the `acknowledgment number` is only valid if the `ACK` flag of the TCP header is set. In practice, almost all [#fackflag]_ TCP segments have their `ACK` flag set. 388/10000 · 388
80 ../../protocols/tcp.rst:251
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — `window`. a TCP receiver uses this 16 bits field to indicate the current size of its receive window expressed in bytes. 119/10000 · 119
81 ../../protocols/tcp.rst:255
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The Transmission Control Block 30/10000 · 30
82 ../../protocols/tcp.rst:257
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — For each established TCP connection, a TCP implementation must maintain a Transmission Control Block (:term:`TCB`). A TCB contains all the information required to send and receive segments on this connection :rfc:`793`. This includes [#ftcpurgent]_ : 250/10000 · 250
83 ../../protocols/tcp.rst:259
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — the local IP address 20/10000 · 20
84 ../../protocols/tcp.rst:260
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — the remote IP address 21/10000 · 21
85 ../../protocols/tcp.rst:261
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — the local TCP port number 25/10000 · 25
86 ../../protocols/tcp.rst:262
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — the remote TCP port number 26/10000 · 26