Path: csiph.com!aioe.org!.POSTED!not-for-mail From: =?UTF-8?Q?Arne_Vajh=c3=b8j?= Newsgroups: comp.lang.java.programmer Subject: Re: Ftp between two machines but ftp transfer started from a 3:rd one. Date: Thu, 15 Sep 2016 20:57:47 -0400 Organization: Aioe.org NNTP Server Lines: 30 Message-ID: References: <84c912e2-5fc1-4d8b-b194-0677f96b0c14@googlegroups.com> NNTP-Posting-Host: 7SK6yTFfqwlIPNBLl3l7Qg.user.gioia.aioe.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Complaints-To: abuse@aioe.org User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.3.0 X-Notice: Filtered by postfilter v. 0.8.2 Xref: csiph.com comp.lang.java.programmer:35618 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