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From: solensky@interlan.interlan.COM (Frank Solensky)
Newsgroups: comp.protocols.tcp-ip
Subject: FTP command/data synchronization
Message-ID: <8911071945.AA02611@interlan.interlan.com>
Date: 7 Nov 89 19:45:29 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 33


	Is there any specific requirement that reply codes sent over an
FTP control connection be synchronized with the packets transmitted over
the data connection?  I've checked through both RFCs 1123 and 959 a few times
and have found quotes that imply that they both must be in synch and aren't
expected to be in synch but haven't come up with anything conclusive.
(However, many in the former category seem to be based on an assumption that
the phrase "close(d) the connection" == "send(/received) a FIN").

	When some client FTP program is being used to pull a file across the
net, a time-sequence diagram of what is occuring is this (stream data
connection, using SO_NODELAY):

	FTP client	net traffic		FTP server
	----------	-----------		----------
	GET file
			C-> RETR file (WIN > 0)
						ds = socket()
	opens a socket
			D-> SYN,WIN=0 (et al)
						send() file
						close(ds)
			C<- "226 closing connection" message
			D-> WIN > 0
			D<- data
			D<- FIN

What I'm looking for is some passage in either RFC or some other source that
states this is or is not acceptable.

TIA.						Frank Solensky
						Racal InterLan
or