Xref: utzoo comp.dcom.lans:1395 comp.protocols.tcp-ip:3624
Path: utzoo!attcan!uunet!husc6!mit-eddie!interlan!backman
From: backman@interlan.UUCP (Larry Backman)
Newsgroups: comp.dcom.lans,comp.protocols.tcp-ip
Subject: FTP server question
Message-ID: <535@interlan.UUCP>
Date: 23 May 88 16:24:36 GMT
Reply-To: backman@mercury.UUCP (Larry Backman)
Distribution: na
Organization: MICOM-Interlan, Boxborough, MA (1-800-LAN-TALK)
Lines: 71



	[]

	An FTP puzzle for the protocol whizes on the net.  Consider the
	following two sniffer packets from a long trace:

	Packet 1 contains a FTP servers Hello message without a CR/LF.
	Packet 2 contains the CR/LF.

	RFC 959, section 4.2 of the DDN protocol handbook Page 2-773 and 2-774
	clearly state:

	       "A reply is defined to contain the 3 digit code, followed
		by Space <SP>, followed by one line of text (where some
		maximum line length has been specified), and terminated by the
		Telnet end of line code."


	At first glance, the FTP server is at fault.  However, in their
	defense,  FTP uses TCP, a stream oriented protocol, to ensure 
	reliable delivery.  This means that the data from a stream can 
	come out as one single packet, or in the worst case, dribble out
	as a stream of single bytes.  So in the second case, the split of
	the FTP message, and the TELNET CR/LF is not so bad.

	Needless to say, something bad happens on my end as a result; nothing
	that I can't hack around, but before doing so, I thought the problem
	was interesting enough to solicit some other opinions,


						Larry Backman
						Micom - Interlan

 - - - - - - - - - - - - - - - - Frame 63 - - - - - - - - - - - - - - - - -

SUMMRY  Delta T     Destination   Source        Summary
   63    0.0291  02070100B550 080014302203  FTP R PORT=1230 220 MIND FTP server (EXOS Version 4.5 Mon Sep 8 08...

FTP:  ----- FTP data -----
FTP:  
FTP:  220 MIND FTP server (EXOS Version 4.5 Mon Sep 8 08...
FTP:  

ADDR  HEX                                                ASCII
0000  02 07 01 00 B5 50 08 00  14 30 22 03 08 00 45 00  .....P...0"...E.
0010  00 71 66 A9 00 00 3C 06  15 02 80 A6 80 83 80 A6  .qf...<.........
0020  81 0C 00 15 04 CE 03 12  DD C2 00 A1 51 42 50 18  ............QBP.
0030  10 00 16 27 00 00 32 32  30 20 4D 49 4E 44 20 46  ...'..220 MIND F
0040  54 50 20 73 65 72 76 65  72 20 28 45 58 4F 53 20  TP server (EXOS 
0050  56 65 72 73 69 6F 6E 20  34 2E 35 20 4D 6F 6E 20  Version 4.5 Mon 
0060  53 65 70 20 38 20 30 38  3A 34 31 3A 31 37 20 50  Sep 8 08:41:17 P
0070  44 54 20 31 39 38 36 29  20 72 65 61 64 79 2E     DT 1986) ready.



- - - - - - - - - - - - - - - - Frame 64 - - - - - - - - - - - - - - - - -

SUMMRY  Delta T     Destination   Source        Summary
   64    0.0001  02070100B550 080014302203  FTP R PORT=1230 <0D><0A>

FTP:  ----- FTP data -----
FTP:  
FTP:  <0D><0A>
FTP:  

ADDR  HEX                                                ASCII
0000  02 07 01 00 B5 50 08 00  14 30 22 03 08 00 45 00  .....P...0"...E.
0010  00 2A 66 AA 00 00 3C 06  15 48 80 A6 80 83 80 A6  .*f...<..H......
0020  81 0C 00 15 04 CE 03 12  DE 0B 00 A1 51 42 50 18  ............QBP.
0030  10 00 58 00 00 00 0D 0A  30 20 4D 49              ..X.....0 MI