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Re: Ftp between two machines but ftp transfer started from a 3:rd one.

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On 9/15/2016 11:09 AM, Martin Gregorie wrote:
> On Thu, 15 Sep 2016 05:55:17 -0700, mike wrote:
>> We are looking into ftp:ing between two machines ( call them A and B)
>> and the the ftp transfer should be started from a third machine ( call
>> it C). Has anyone done this before, using java?
>>
> I do it all the time, but by logging into machine C and starting an SSH
> session on A, from which I run ftp transfers between machines A and B. I
> realise this is probably not what you want, but if you supplied bit more
> detail that would help people to give more relevant advice. Some
> questions:
>
> - what will cause machine C to start the FTP session?
>     IOW will it be manually started?
>     Automatically triggered by some sort of timer?
>     Triggered by some other event?

This capability is build into the FTP protocol.

The trick is the fact that FTP uses two connections: command
and data. That is usually just a hassle. But it is what enable this.

FTP client on C makes command connection to A.
FTP client on C makes command connection to B.
FTP client uses command connection to tell B to listen for data connection.
FTP client uses command connection to tell A to establish data 
connection to B

Arne

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Ftp between two machines but ftp transfer started from a 3:rd one. mike <mikaelpetterson@hotmail.com> - 2016-09-15 05:55 -0700
  Re: Ftp between two machines but ftp transfer started from a 3:rd one. Martin Gregorie <martin@address-in-sig.invalid> - 2016-09-15 15:09 +0000
    Re: Ftp between two machines but ftp transfer started from a 3:rd one. Arne Vajhøj <arne@vajhoej.dk> - 2016-09-15 20:57 -0400
  Re: Ftp between two machines but ftp transfer started from a 3:rd one. Arne Vajhøj <arne@vajhoej.dk> - 2016-09-15 21:07 -0400

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