[ih] FTP RIP

[John Day]

See below.

> On Sep 27, 2020, at 21:54, Grant Taylor via Internet-history <internet-history at elists.isoc.org> wrote:
> 
> On 9/27/20 7:29 PM, Joseph Touch via Internet-history wrote:
>> This thread begs the question of where we’d be had TBL had tried to leverage FTP rather than reinventing the wheel with HTTP.
> 
> I feel like I've dabbled with this in the past.  E.g. retrieved an HTML page via FTP and used ftp:// links in the src parameters for elements.
> 
> I want to say I did similar with Gopher.  Or rather, I created a local file that used a gopher:// link for the source of an image that I knew was on a Gopher server.
> 
> I seem to recall it working surprisingly well.  Though it wasn't practical.
> 
>> I recall an early interview that claimed the rationale was that FTP opened two connections for every transfer and he only wanted one.
> 
> I don't know that that's /completely/ accurate per say.  Yes, there are two connections; control and data.  But I believe the control connection can be re-used for multiple subsequent data connections.

The control connection was a Telnet connection and assumed to be ASCII. The purpose was so that commands did not get blocked behind data. Also, for TIPS, the user FTP process was you. You typed the commands.

The data connection was normally a fixed offset from the Telnet connection. (NCP sockets were simplex, so there was one for each direction.) The data connection was not ASCII. The data connection was assumed to be binary.  The only time the Control connection was used for data transfer was for the MAIL command as opposed to the MLFL command that used the data connection.  For the TIPs, devices like a printer or card reader could be ‘hardwired’ to a given socket. The SOCKet command was used to not use the default data connections.
 
> 
> Firewalling and NATing are two of FTP's Achilles Heals.  Specifically FTPS.

Isn’t that a bit backwards? Since FTP was done decades before either one.
> 
> Aside SFTP (SSH) is significantly different than FTPS (FTP over SSL / TLS).

Unlike HTTP, FTP required a login. FTP is, in a sense, the first application protocol. (Telnet and NCP were ‘in the OS.’ Telnet was a terminal device driver protocol.)
> 
>> It’s been unfortunate how many of FTP’s features had to be (or still remain to be) reinvented in HTTP.
> 
> I learned in the last few years that it's possible to establish FTP connections with two servers and instruct them to exchange data directly between themselves without traversing the common client.  Or at least the protocol supports it.  I'm not aware of it being a common implementation, much less execution.  --  I do think that FTPS may hinder this somewhat.

That has been there since at least 1973. There are no special commands and nothing special for doing that. It is just using the existing commands to do it.

Take care,
John

> 
> 
> 
> -- 
> Grant. . . .
> unix || die
> 
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