Using Secure Shell FTP (SFTP)

Topics:

Using SFTP from Windows

Before using SFTP with DataMigrator, you need to set up SSH connections without passwords.

For example, if your DataMigrator Server is a on a Linux system called local and you want to retrieve or write files on a server called remote, you should log on to your local system with your user ID, for example, user. Then, you need to generate a key file:

/home/user/$ ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/home/user/.ssh/id_rsa): 
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/user/.ssh/id_rsa.
Your public key has been saved in /home/user/.ssh/id_rsa.pub.
The key fingerprint is:
10:7d:25:cb:ff:1d:c5:f4:1e:dc:7d:44:20:fd:21:56 home@local
/home/user/$

This process creates two files in your .ssh directory: your private key id_rsa and your public key id_rsa.pub. Then, you need to add your public key to the authorized users on the remote server. You can do this using FTP. Enter the name of your remote server for remote.

Note: When you issue the command to create the remote directory (.ssh), it will fail if it already exists. This is not an issue.

/home/user$ ftp remote
Connected to remote (172.19.23.42).
220 (vsFTPd 2.2.2)
Name (remote:user):
331 Please specify the password.
Password: password
230 Login successful.
Remote system type is UNIX.
Using binary mode to transfer files.
ftp> lcd .ssh
Local directory now /home/user/.ssh

ftp> mkdir .ssh
257 "/home/user/.ssh" created
ftp> cd .ssh
250 Directory successfully changed.
ftp> append id_rsa.pub authorized_keys
local: id_rsa.pub remote: authorized_keys
227 Entering Passive Mode (172,19,23,42,91,225).
150 Ok to send data.
226 Transfer complete.
223 bytes sent in 4.2e-05 secs (5.2e+03 Kbytes/sec)
ftp> quit
221 Goodbye.

You can verify if this worked by using SFTP. You should not get prompted for a password.

/home/user/$ sftp user@remote
Connecting to remote...
sftp> quit
/home/user/$

Your connection is now set up. In the Data Management Console, expand the Adapters folder. Then expand the Configured folder. Right-click Delimited Flat File (or Flat File) and click Add Connection. You can now select SFTP as the transfer protocol.

Using SFTP from Windows

While Windows does not include an SFTP client program, there are programs available from both open source and commercial sources that implement the protocol.

One free source is PuTTY, which supplies a collection of utilities including a client program (psftp.exe) with similar functionality. They also provide puttygen.exe for generating private or public key pairs and converting an existing private key to a file in their .ppk format.

To use PuTTY's PSFTP:

Go to the PuTTY Download Page, download the MSI installer, and run it to install and configure their utilities. Alternatively, download psftp.exe and puttygen.exe to a directory in your PATH.
Download a private key to your Windows system or generate a new key using puttygen. Save it to a directory of your choice, for example, C:\putty\id_rsa.ppk.
If necessary, add your public key to ~/.ssh/authorized_keys on the remote server.
Test the connection from the command line using the following lines:
```
drive:\> psftp -v -i "drive:\putty\id_rsa.ppk" user@remote 
Using username "user"
The server's host key is not cached in the registry
...
Store key in cache? (y/n) y
Remote working directory is /home/user
psftp> ls
psftp> quit
```
where:

drive

Is the drive on which the private key is saved.

user

Is your user ID.

remote

Is the name of your remote server.

You should not be prompted for a password or passphrase. However, if you have not previously connected to the server, you will be prompted to store the key in the cache. Reply y and you will not be prompted again. You must do this so that the DataMigrator Server does not receive this prompt.
In your PATH, create a file called sftp.bat with the following lines:
```
@echo off
psftp -i "drive:\putty\id_rsa.ppk" %1 %4 %5 %6 –batch
```
where:

drive

Is the drive on which the private key is saved.

If your DataMigrator Server is running, shut it down and then start it again. You can now configure a connection for a (delimited) flat file for a remote connection using SFTP.

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