w8sdz%brl@sri-unix.UUCP (08/08/83)
From: Keith Petersen <w8sdz@brl>
In view of all the discussion about transferring CP/M files
on the Arpanet, I felt that forwarding the following message
would be useful. It's one of the best descriptions of what
FTP is. Appologizes to anyone who received duplicate copies
because of my forwarding.
--Keith
----- Forwarded message # 1:
Received: From Sri-Unix.ARPA by BRL via smtp; 8 Aug 83 3:16 EDT
Received: from Usenet.uucp by SRI-Unix.uucp with rs232; 7 Aug 83 18:25-PDT
Date: 7 Aug 83 12:01:23-PDT (Sun)
To: info-micro @ Brl
From: harpo!eagle!mhuxt!mhuxi!aluxz!glennw @ Ucb-Vax
Subject: FTP help?
Article-I.D.: aluxz.269
I have seen numerous references on the net referring to FTP. It is associated
with INFO-IBMPC and [COLUMBIA-20]. As near as I can determine it is a cache
of public domain software. Can anyone give me an explanation of what FTP
is, how it is used, etc.?
Thanks.
Glenn Wesley
aluxz!glennw
----- Forwarded message # 2:
Received: From Sri-Kl.ARPA by BRL via smtp; 8 Aug 83 12:48 EDT
Date: 8 Aug 1983 09:43-PDT
Sender: BILLW@SRI-KL
Subject: Re: FTP help?
From: BILLW@SRI-KL
To: harpo!eagle!mhuxt!mhuxi!aluxz!glennw@UCB-VAX
Cc: info-micro@BRL
Message-ID: <[SRI-KL] 8-Aug-83 09:43:54.BILLW>
In-Reply-To: The message of 7 Aug 83 12:01:23-PDT (Sun) from harpo!eagle!mhuxt!mhuxi!aluxz!glennw@ucb-vax
Well, you see, on a real network (In this case, the ARPANet/Internet),
you are able to transfer files directly between arbitary hosts on the
internet, using something called the "File Tranfer Protocol" (FTP).
To get a file from, say, the CPM library at Simtel20 to my home system
(SRI-KL), I log in on SRI-KL, run the FTP program and ask it to
connect me to Simtel20. FTP uses the lower level reliable
transmission protocols for the actual data transfer, but the user
program (along with a server program on the other computer) takes care
of things like accounting, access control, file format conversion (eg
text, 8bit, 36bit, page, etc), etc. FTP uses multiple "connections" so
that data transfers can be interupted, for example.
A representative set of low level commands used in the FTP protocol
is USER, PASSWORD, ACCOUNT, STRUCTURE, MODE, TYPE, RETREIVE, STORE,
ALLOCATE, APPEND, DELETE, ABORT, LIST, CHANGE DIRECTORY, STATUS.
The following picture is taken from RFC765 - The FTP protocol specification.
-------------
|/---------\|
|| User || --------
||Interface|<--->| User |
|\----:----/| --------
---------- | V |
|/------\| FTP Commands |/---------\|
||Server|<---------------->| User ||
|| PI || FTP Replies || PI ||
|\--:---/| |\----:----/|
| V | | V |
-------- |/------\| Data |/---------\| --------
| File |<--->|Server|<---------------->| User |<--->| File |
|System| || DTP || Connection || DTP || |System|
-------- |\------/| |\---------/| --------
---------- -------------
Server-FTP User-FTP
NOTES: 1. The data connection may be used in either direction.
2. The data connection need not exist all of the time.
3. PI = Protocol interpreter
4. DTP = Data transfer process
If you think of FTP as a real-time, interactively driven UUCP designed
with transferring files between systems running arbitrary Operating systems
with arbirary file systems, You'll have about the right idea. Some files
mad available for FTP make it to net.sources, however since FTP data rates
vary from about 8K bps accross the country to people on very-distant-host
adaptors or ecus (eg: rutgers), to 300K bps over local ethernets, it isnt
partical to make everything available for FTPing also available for UUCPing.
Bill Westfield
----- End of forwarded messages