Receive File via SFTP/SSH and automatically forwar

问题:

I'm currently in a situation where I receive flat files via FTP from my clients. A couple of clients have insisted on the need to use SSH Private Key SFTP rather than regular FTP.

What I want to do is setup a web server (preferably in linux/unix but I guess I can do it on a windows server and purchase SFTP server software) that will do the following:

1. Allow me to setup an SFTP directory for each client with unique user/pass. Each directory also has to have the public/private key SSH "stuff" I'm a little new to this but I've googled it.

2. Once the file is completely uploaded by the client, I want to kick off an event that ftp's that file via regular FTP to my Windows cloud.

3. These files can be up to 10mb so the even that ftp's to the other server can't fire until the file is completely uploaded.

Has anyone set something like this up? Any guidance would be appreciated.

Thanks!

回答1:

In Linux, you can use incron to monitor the directory the files will be SFTP'd to and have it trigger your ftp job. It's kind of like cron except that instead of triggering jobs based on time, it does so based on filesystem modifications. In order to only trigger once the entire file has been written, I think you can use IN_CLOSE_WRITE in the inotify mask. Failing this, I suggest configuring events for each of the events individually to echo a message to a log file and see if you can identify one which reliably happens only at the end of the SFTP transfer.

If you're using RedHat, it's not in the standard distribution, but it is in EPEL.

回答2:

On Windows you could use Titan FTP Server Enterprise Edition, which supports SFTP as well as allows you to define various types of events. When the event is triggered, you could kick off anything you need on a per folder/per account basis.

PS. AFAIK, when it comes to SFTP it is either password authentication or public key authentication (SSH key), but not both.

回答3:

In your UNIX server, you can configure SSH to use a custom sftp server that instead of handling SFTP protocol itself, opens a new SSH connection to to the Windows SFTP server using password authentication and forwards the SFTP traffic there.

Writting the proxy is easy with the right tools, for instance, in Perl using the Net::OpenSSH module:

#!/usr/bin/perl
# this is the sftp-proxy-server

use Net::OpenSSH;
my $ssh = Net::OpenSSH->new($windows_server, $user, $passwd);
$ssh->system({ssh_opts => '-s'}, 'sftp');
$ssh->error and die $ssh->error;

You can instruct the SSH server to use that alternative SFTP server changing the configuration in /etc/ssh/sshd_config. For instance:

Subsystem sftp /usr/local/bin/sftp-proxy-server

回答4:

Did you try apache FTP Serveur ?

I think you can do what you need with the ftplet API.

see : http://mina.apache.org/ftpserver-project/index.html