[COFF] Today I learned something new about File Transfer Protocol.

[gtaylor at tnetconsulting.net (Grant Taylor)]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain, Size: 1728 bytes --]

Today I learned that File Transfer Protocol supports transferring data 
between two remote systems without passing the data through a 
controlling host.

The end of § 2.3, The FTP Model, of RFC 959, File Transfer Protocol, 
states the following:

"""
In another situation a user might wish to transfer files between two 
hosts, neither of which is a local host. The user sets up control 
connections to the two servers and then arranges for a data connection 
between them.  In this manner, control information is passed to the 
user-PI but data is transferred between the server data transfer 
processes.  Following is a model of this server-server interaction.

                   Control    ------------    Control
                   ---------->| User-FTP |<-----------
                   |          | User-PI  |           |
                   |          |   "C"    |           |
                   V          ------------           V
           --------------                        --------------
           | Server-FTP |   Data Connection      | Server-FTP |
           |    "A"     |<---------------------->|    "B"     |
           -------------- Port (A)      Port (B) --------------
"""

I also learned that FTP uses (a subset of) the Telnet protocol for it's 
control connection.  Yet another reason to dislike it.  (I strongly 
prefer 8-bit clean connections and dislike things that need special 
handling.)



-- 
Grant. . . .
unix || die

-------------- next part --------------
A non-text attachment was scrubbed...
Name: smime.p7s
Type: application/pkcs7-signature
Size: 3982 bytes
Desc: S/MIME Cryptographic Signature
URL: <http://minnie.tuhs.org/pipermail/coff/attachments/20180707/ec76f8f9/attachment.bin>