📄 rfc1350.4up.ps
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5 205 M( 5-3 depicts an ACK packet; the opcode is 4. The block number in) s5 192 M( an ACK echoes the block number of the DATA packet being) s5 179 M( acknowledged. A WRQ is acknowledged with an ACK packet having a) s5 166 M( block number of zero.) s5 49 M(Sollins [Page 7]) s_R%Page: (8) 8%BeginPageSetup_S% N-up sub-page 4/4278 -794 translate0.490859 dup scale/pagenum 8 def/fname (/usr/local/share/doc/rfc/Mirrors/ftp.isi.edu/in-notes/rfc1350.txt) def/fdir (/usr/local/share/doc/rfc/Mirrors/ftp.isi.edu/in-notes/) def/ftail (rfc1350.txt) def% User defined strings:/fmodstr (Wed Jul 08 00:00:00 1992) def/pagenumstr (8) def/user_header_p true def/user_header_left_str (RFC1350) def/user_header_center_str (RFC.net) def/user_header_right_str (Page 8 of 11) def%%EndPageSetupdo_header5 751 M(RFC 1350 TFTP Revision 2 July 1992) s5 712 M( 2 bytes 2 bytes string 1 byte) s5 699 M( -----------------------------------------) s5 686 M( | Opcode | ErrorCode | ErrMsg | 0 |) s5 673 M( -----------------------------------------) s5 647 M( Figure 5-4: ERROR packet) s5 608 M( An ERROR packet \(opcode 5\) takes the form depicted in Figure 5-4. An) s5 595 M( ERROR packet can be the acknowledgment of any other type of packet.) s5 582 M( The error code is an integer indicating the nature of the error. A) s5 569 M( table of values and meanings is given in the appendix. \(Note that) s5 556 M( several error codes have been added to this version of this) s5 543 M( document.\) The error message is intended for human consumption, and) s5 530 M( should be in netascii. Like all other strings, it is terminated with) s5 517 M( a zero byte.) s5 491 M(6. Normal Termination) s5 465 M( The end of a transfer is marked by a DATA packet that contains) s5 452 M( between 0 and 511 bytes of data \(i.e., Datagram length < 516\). This) s5 439 M( packet is acknowledged by an ACK packet like all other DATA packets.) s5 426 M( The host acknowledging the final DATA packet may terminate its side) s5 413 M( of the connection on sending the final ACK. On the other hand,) s5 400 M( dallying is encouraged. This means that the host sending the final) s5 387 M( ACK will wait for a while before terminating in order to retransmit) s5 374 M( the final ACK if it has been lost. The acknowledger will know that) s5 361 M( the ACK has been lost if it receives the final DATA packet again.) s5 348 M( The host sending the last DATA must retransmit it until the packet is) s5 335 M( acknowledged or the sending host times out. If the response is an) s5 322 M( ACK, the transmission was completed successfully. If the sender of) s5 309 M( the data times out and is not prepared to retransmit any more, the) s5 296 M( transfer may still have been completed successfully, after which the) s5 283 M( acknowledger or network may have experienced a problem. It is also) s5 270 M( possible in this case that the transfer was unsuccessful. In any) s5 257 M( case, the connection has been closed.) s5 231 M(7. Premature Termination) s5 205 M( If a request can not be granted, or some error occurs during the) s5 192 M( transfer, then an ERROR packet \(opcode 5\) is sent. This is only a) s5 179 M( courtesy since it will not be retransmitted or acknowledged, so it) s5 166 M( may never be received. Timeouts must also be used to detect errors.) s5 49 M(Sollins [Page 8]) s_R_RS%%Page: (9-12) 3%%BeginPageSetup_S24 818 translate%Page: (9) 9%BeginPageSetup_S% N-up sub-page 1/40 -392 translate0.490859 dup scale/pagenum 9 def/fname (/usr/local/share/doc/rfc/Mirrors/ftp.isi.edu/in-notes/rfc1350.txt) def/fdir (/usr/local/share/doc/rfc/Mirrors/ftp.isi.edu/in-notes/) def/ftail (rfc1350.txt) def% User defined strings:/fmodstr (Wed Jul 08 00:00:00 1992) def/pagenumstr (9) def/user_header_p true def/user_header_left_str (RFC1350) def/user_header_center_str (RFC.net) def/user_header_right_str (Page 9 of 11) def%%EndPageSetupdo_header5 751 M(RFC 1350 TFTP Revision 2 July 1992) s5 712 M(I. Appendix) s5 686 M(Order of Headers) s5 660 M( 2 bytes) s5 647 M( ----------------------------------------------------------) s5 634 M( | Local Medium | Internet | Datagram | TFTP Opcode |) s5 621 M( ----------------------------------------------------------) s5 595 M(TFTP Formats) s5 569 M( Type Op # Format without header) s5 543 M( 2 bytes string 1 byte string 1 byte) s5 530 M( -----------------------------------------------) s5 517 M( RRQ/ | 01/02 | Filename | 0 | Mode | 0 |) s5 504 M( WRQ -----------------------------------------------) s5 491 M( 2 bytes 2 bytes n bytes) s5 478 M( ---------------------------------) s5 465 M( DATA | 03 | Block # | Data |) s5 452 M( ---------------------------------) s5 439 M( 2 bytes 2 bytes) s5 426 M( -------------------) s5 413 M( ACK | 04 | Block # |) s5 400 M( --------------------) s5 387 M( 2 bytes 2 bytes string 1 byte) s5 374 M( ----------------------------------------) s5 361 M( ERROR | 05 | ErrorCode | ErrMsg | 0 |) s5 348 M( ----------------------------------------) s5 322 M(Initial Connection Protocol for reading a file) s5 296 M( 1. Host A sends a "RRQ" to host B with source= A's TID,) s5 283 M( destination= 69.) s5 257 M( 2. Host B sends a "DATA" \(with block number= 1\) to host A with) s5 244 M( source= B's TID, destination= A's TID.) s5 49 M(Sollins [Page 9]) s_R%Page: (10) 10%BeginPageSetup_S% N-up sub-page 2/4278 -392 translate0.490859 dup scale/pagenum 10 def/fname (/usr/local/share/doc/rfc/Mirrors/ftp.isi.edu/in-notes/rfc1350.txt) def/fdir (/usr/local/share/doc/rfc/Mirrors/ftp.isi.edu/in-notes/) def/ftail (rfc1350.txt) def% User defined strings:/fmodstr (Wed Jul 08 00:00:00 1992) def/pagenumstr (10) def/user_header_p true def/user_header_left_str (RFC1350) def/user_header_center_str (RFC.net) def/user_header_right_str (Page 10 of 11) def%%EndPageSetupdo_header5 751 M(RFC 1350 TFTP Revision 2 July 1992) s5 712 M(Error Codes) s5 686 M( Value Meaning) s5 660 M( 0 Not defined, see error message \(if any\).) s5 647 M( 1 File not found.) s5 634 M( 2 Access violation.) s5 621 M( 3 Disk full or allocation exceeded.) s5 608 M( 4 Illegal TFTP operation.) s5 595 M( 5 Unknown transfer ID.) s5 582 M( 6 File already exists.) s5 569 M( 7 No such user.) s5 543 M(Internet User Datagram Header [2]) s5 517 M( \(This has been included only for convenience. TFTP need not be) s5 504 M( implemented on top of the Internet User Datagram Protocol.\)) s5 478 M( Format) s5 452 M( 0 1 2 3) s5 439 M( 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) s5 426 M( +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+) s5 413 M( | Source Port | Destination Port |) s5 400 M( +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+) s5 387 M( | Length | Checksum |) s5 374 M( +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+) s5 335 M( Values of Fields) s5 296 M( Source Port Picked by originator of packet.) s5 270 M( Dest. Port Picked by destination machine \(69 for RRQ or WRQ\).) s5 244 M( Length Number of bytes in UDP packet, including UDP header.) s5 218 M( Checksum Reference 2 describes rules for computing checksum.) s5 205 M( \(The implementor of this should be sure that the) s5 192 M( correct algorithm is used here.\)) s5 179 M( Field contains zero if unused.) s5 153 M( Note: TFTP passes transfer identifiers \(TID's\) to the Internet User) s5 140 M( Datagram protocol to be used as the source and destination ports.) s5 49 M(Sollins [Page 10]) s_R%Page: (11) 11%BeginPageSetup_S% N-up sub-page 3/40 -794 translate0.490859 dup scale/pagenum 11 def/fname (/usr/local/share/doc/rfc/Mirrors/ftp.isi.edu/in-notes/rfc1350.txt) def/fdir (/usr/local/share/doc/rfc/Mirrors/ftp.isi.edu/in-notes/) def/ftail (rfc1350.txt) def% User defined strings:/fmodstr (Wed Jul 08 00:00:00 1992) def/pagenumstr (11) def/user_header_p true def/user_header_left_str (RFC1350) def/user_header_center_str (RFC.net) def/user_header_right_str (Page 11 of 11) def%%EndPageSetupdo_header5 751 M(RFC 1350 TFTP Revision 2 July 1992) s5 712 M(References) s5 686 M( [1] USA Standard Code for Information Interchange, USASI X3.4-1968.) s5 660 M( [2] Postel, J., "User Datagram Protocol," RFC 768, USC/Information) s5 647 M( Sciences Institute, 28 August 1980.) s5 621 M( [3] Postel, J., "Telnet Protocol Specification," RFC 764,) s5 608 M( USC/Information Sciences Institute, June, 1980.) s5 582 M( [4] Braden, R., Editor, "Requirements for Internet Hosts --) s5 569 M( Application and Support", RFC 1123, USC/Information Sciences) s5 556 M( Institute, October 1989.) s5 530 M(Security Considerations) s5 504 M( Since TFTP includes no login or access control mechanisms, care must) s5 491 M( be taken in the rights granted to a TFTP server process so as not to) s5 478 M( violate the security of the server hosts file system. TFTP is often) s5 465 M( installed with controls such that only files that have public read) s5 452 M( access are available via TFTP and writing files via TFTP is) s5 439 M( disallowed.) s5 413 M(Author's Address) s5 387 M( Karen R. Sollins) s5 374 M( Massachusetts Institute of Technology) s5 361 M( Laboratory for Computer Science) s5 348 M( 545 Technology Square) s5 335 M( Cambridge, MA 02139-1986) s5 309 M( Phone: \(617\) 253-6006) s5 283 M( EMail: SOLLINS@LCS.MIT.EDU) s5 49 M(Sollins [Page 11]) s_R_RS%%Trailer%%Pages: 11%%DocumentNeededResources: font Courier Times-Italic %%EOF⌨️ 快捷键说明
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