Copying files from one machine to another without asking for password

Question

I am currently using this command. I am on another machine (ip1)

scp file.txt root@ip2:/home/praveen/test.c /home/praveen

The command will prompt for password.

I use it in some shell scripts, and am calling these scripts from some crontab files. So, I can not enter the password every time. Is there any way to disable password asking or some another way to input password from somewhere, so that I don't need to enter it again.

And I cannot use ssh-keygen, because I have to do the actions for these scripts only. When I use ssh-keygen, it will never prompt me for password again. I don't want this. Rest of the things should work as usual.

Solution 1

It was not clear why you could not use ssh-keygen and the subsequent key exchange. I believe this is the recommended practice.

An alternative would be to use the expect command (online man pages). This can eliminate user intervention in the interactive processes. As the name suggests, it expects a prompt, and responds accordingly as specified to it.

Look at this solution of automating SSH using expect. To quote a few lines:

# Look for passwod prompt
expect "*?assword:*"
# Send password aka $password
send -- "$password\r"

The second line specifies the prompt that appears. In this case, it asks for password. The fourth line sends the password to the server.

Solution 2

You could use ftp, if that's allowed on the remote server. Here's a sample of shell script I used for this purpose

HOST='remote.server.com'
USER='domainname/usrid'   
PASSWD='p@@ssw0rd'
cd /path/to/local/directory/containing/the/file/to/be/transferred
`ftp -n $HOST <<END_SCRIPT
quote USER $USER
quote PASS $PASSWD
cd /diretory/on/remote/server
put file2transfer.dat 
bye    
quit
END_SCRIPT`

Comments

[Marek Zakrzewski]

You need to configure public/private key authentication for your host/client.

[slm]

possible duplicate of SCP from one server to another without password prompt

[Sepahrad Salour]

You asked this question in toolbox.com later and you got the answer I think.

[terdon]

This is not a duplicate, the OP specifically mentions that s/he does not want to use ssh-keygen.

[mike]

Indeed simple. But I don't know where OP works, or if it's private. But having the pw in plaintext in a script or even in his command history seems a little bit unsecure.

[mike]

+1. Never heard of expect. Learned sth!

[slm]

Yes this works, but it's a bad idea. The password is sent in the clear, better to use public/private keys!

[slm]

This also leaks the password in the clear, just like Christos' answer. As @Barun is most definitely aware and just trying to answer your question, any method other than public/private keys is a bad idea.

[Gilles 'SO- stop being evil']

This means writing the password in a file, which is even worse than having a passwordless private key.

[kurtm]

Does it work? Most things that prompt for a password directly use the users tty, which is part of why expect was created in the first place. That is beyond the fact that it's a bad idea to start with.