Shell Programming and Scripting

As part of our project dev , we need to create a shell script that
COPY FILES FROM A SEPCIFIC DIRETORY OF THE LOCAL SYSTEM INTO A SPECIFIC LOCATION OF A REMOTE SERVER.

Code:

USER1@SERVER1/Dir1/*.* ------- >USER2@SERVER2/Dir2

The main issues with this is requirement are :
1. THERE'S ONLY ONE SPECIFIC USERID (USER1) CONFIGURED TO THE SOURCE SYSTEM WHICH HAS PRIVILDEGES OF FILE TRANSFER FROM SERVER1 TO ANY OTHER REMOTE SERVER, HENCE WHATEVER SESSION MAY THE SHELL SCRIPT RUN IN, IT NEEDS TO SET IN SUCH A WAY SO AS TO EXECUTE THE FILE TRANSFER PROCESS USING THE SESSION OF USER1 ONLY
2.IF I AM USING THE SCP COMMAND , HOW WILL I BE ABLE TO AUTOMATE THE PASSING OF PASSWORDS TO THE SCRIPT ?

Any other alternatives will be higly regarded.

Additonal Info : I am using Korn Shell to build the script.

Thanks
Kumarjit.

Passwords are less secure than setting up a nice long PPKey so the acting user has access to the other user's account. Otherwise, as passwords in ssh scp sftp are read from /dev/tty to discourage this, you need to run scp in something like 'expect' to be able to write the pseudo tty of the scp with the visible password.

Hai DGPickett,

I am a kid in unix,i request you to explain in such a way that i can understud the above published comments..

Thanks & Regards
-----------------
Anil Kumar

'interactive password authentication' means 'password typed by a human being in realtime authentication' and no artificial substitutes for 'human' are acceptable. This is because stored passwords are almost impossible to keep safe.

Fortunately, there's a much better way to automate ssh/scp/sftp passwords -- keys. (Note that ssh, sftp, scp all use the same protocol, and the same keys.) They were designed for this purpose. Just having the right files in the right places on both the client and the server will allow the client to login to the server automatically.

Instead of sending a password, it sends an encrypted key. This key is generated by the ssh-keygen command.

It resides in the ~/.ssh/ directory on both the client and server. The client has the key files themselves. The server just has the key listed in authorized_keys.

If you have the ssh-copy-id command, this will be brief and simple to set up from the client:

Code:

# Just hit enter to all the questions this asks you
$ ssh-keygen -t rsa

$ ssh-copy-id username@host

# Should now login without a password
$ ssh username@host

Yes, the ssh-keygen generates a public and private key. The script installs the public key in the other sytem-user's trusted users file, and you are now connecting passwordlessly. Keys are stored in ~/.ssh/ or ~/.ssh2/ unless it is a mount point, and then it is configured to a different subtree.

There are also trusted keys for the hosts stored at the client side. Now, the client knows it is talking to the same host, and the user knows it is talking to the same user.

(They encode some data with their private keys and the other side decodes it with their public keys, and that data supports a secured session of a limited length until a new session key is generated.)