automatically pass a password to rsync for remote host.

freakinweirdo · 05-24-2011, 06:53 PM

Hi all,

I need to be able to use an rsync command in script that will be run by cron. And it needs to be able to pass a password to rsync so that the remote server it's connecting to will authenticate.

I cannot set up ssh keys between the two servers, it's not an option.
I cannot use any other language other than bash, it's my only option.
I know this is highly insecure, I have no other option.

So far I have this:
rsync --rsh="/usr/bin/ssh -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null -o PreferredAuthentications=password" -raxv /source/dir/* user@remotehost:/target/directory/.

This allows the script to ignore host verification and goes directly to the password prompt. I need the script to fill in this password prompt with the password that is stored in a variable.

I tried using expect, but I honestly don't know the syntax, it just keeps failing. A lot of the examples I'm finding online for expect starts off with a "spawn", which i don't have installed, and not sure if I have the ability to install it yet.

Any thoughts or tips that can help with this?

Thanks in advance.

TobiSGD · 05-24-2011, 07:17 PM

spawn is not an installed program, it is an Expect keyword. IMHO Expect is exactly the way to do it in your case.

freakinweirdo · 05-24-2011, 07:37 PM

Quote:

Originally Posted by TobiSGD

spawn is not an installed program, it is an Expect keyword. IMHO Expect is exactly the way to do it in your case.

Yeah I'm seeing that now. However I'm still unable to get the syntax for expect right.

Created a file as below

Code:

spawn rsync --rsh="/usr/bin/ssh -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null -o PreferredAuthentications=password" -raxv /source/dir/* user@remotehost:/target/directory/.
expect assword
send blarg\n

and executing it like this:

Code:

expect -f tmp
spawn rsync --rsh="/usr/bin/ssh -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null -o PreferredAuthentications=password" -raxv /source/dir/* user@remotehost:/target/directory/.
Missing trailing-" in remote-shell command.
rsync error: syntax or usage error (code 1) at main.c(335) [sender=2.6.8]
send: spawn id exp6 not open
    while executing
"send blarg\n"
    (file "tmp" line 3)

I'm SURE I'm messing something up, I've seen a dozen ways to use execpt online, and can't get any to work. My brain is fried so I'll be revisiting this tomorrow.

freakinweirdo · 05-24-2011, 08:46 PM

alright I couldn't leave it alone, but as luck would have it, I found http://rootprompt.org/article.php3?article=5760, which finally had a working example for me since I've never used expect.

with that, I wrote up this. I couldn't seem to execute it all as a 'string', so wrote it to a file, executed it, then removed it. It's dirty but it will do for now.

Code:

#!/bin/bash

pass=password
expect="""#!/usr/bin/expect -f 

set timeout  -1

spawn rsync -ravx user@host:from/* to/.
expect  \"password:\" { send \"$pass\\n\"}
expect \"#\"
"""

echo "$expect" > /tmp/temp.sh

chmod 777 /tmp/temp.sh

/tmp/temp.sh

echo "result is [$?]"

if [[ $result -eq 0 ]]; then
        echo "Success"
else
        echo "Failure"
fi

rm -f /tmp/temp.sh

I'd like to get it to execute with except -f, but I'll mess with that later, for now it actually works, so I'm not freaking out :-)

Reuti · 05-25-2011, 02:19 PM

Quote:

Originally Posted by freakinweirdo

I cannot set up ssh keys between the two servers, it's not an option.

What about hostbased authentication? Or running rsync in daemon mode on the target machine and expect a password for connections, which you can set in the cron entry by just setting an environment variable. I do it this way like:

Code:

RSYNC_PASSWORD=DXd94hA9
0 3 * * * rsync -aq --delete Gq3fBtvk@10.0.2.1::my_server /backup/my_server