RFC 478 (rfc478) - Page 2 of 2
FTP server-server interaction - II
Alternative Format: Original Text Document
RFC 478 FTP Server-Server Interaction-II 26 March 1973 +---------------+ | | +----------| USER PROCESS |----------+ | | A | | telnet +---------------+ telnet | | | | +-----------+ +-------------+ | |--------> --------->| | | SERVER |data sockets data socket| SERVER | | B | Sb Sc | C | | |<-------- <---------| | +-----------+ +-------------+ USER A TO SERVER B USER A TO SERVER C __________________ __________________ A->B SOCK HOST-C SKT- Sc A->C SOCK HOST-B SKT- Sb B->A ACK C->A ACK A->B PASV B->A ACK A->B STOR A->C RTRV 1. After the PASV command has been acknowledged, the two data transfer commands can be sent in either order, since the LISTENING action takes place with the PASV command 2. The user knows the socket numbers Sc and Sb to be the data sockets as specified by the protocol. 3. Note that it is not essential for a SOCK command to be sent to the same Host to whom a PASV will be sent. Sending one to him provides security in that the incoming RFC can be checked. RB/nlg [This RFC was put into machine readable form for entry] [into the online RFC archives by Helene Morin, Via Genie 12/1999] Bressler
