Scp command over ssh without password in script

Question

Here is my problem: I would like to perform scp command after ssh to remote server without typing any passwords. I describe my steps. My first steps were:

ssh-keygen -t rsa and

local@host$ ssh-copy-id -i /root/.ssh/id_rsa.pub remote@host on local machine

Then I did the same on remote machine:

ssh-keygen -t rsa and

remote@host$ ssh-copy-id -i /root/.ssh/id_rsa.pub local@host

After all described above I could do ssh on both machines without typing any password. I could perform scp command on remote machine like scp /home/remote/info.txt.gz local@host:/root/ and everything worked perfectly.

Then I tried to make a script with some actions described below and the last step in my script was scp command that did not work as I expected.

#!/bin/bash
remote_user=$1
remote_host=$2
local_user=$3
local_host=$4

echo "Testing connection to ${host}..."
ssh -n -o NumberOfPasswordPrompts=0 ${remote_user}@${remote_host}
if [ $? -ne 0 ]; then
    echo "FATAL: You don't have passwordless ssh working."
    echo "Try running ssh-keygen"
    exit 1
fi
echo "Okey. Starting the process."
ssh ${remote_user}@${remote_host} netstat -tulpn > /home/${remote_user}/info.txt;uptime |awk '{ print $3 }' >> /home/${remote_user}/info.txt;
if [ $? -ne 0 ]; then
    echo "An error occurred."
else
    echo "File is ready for gzipping!"
fi
gzip /home/${remote_user}/info.txt
if [ $? -ne 0 ]; then
    echo "file was not archived"
else
    echo "Archive is ready!"
fi
echo "Starting copy archive from ${remote_host} to ${local_host}"
scp /home/${remote_user}/info.txt.gz ${local_user}@${local_host}:/root/
if [ $? -ne 0 ]; then
    echo "Error while transferring!"
else
    echo "Copy has been transferred successfully!"
fi

Scp command asked me for password o_O.

When I did all steps in script manually everything worked perfectly but in script scp demanded password. I read a lot through stackexchange and found this answer Using an already established SSH channel. This answer requires Open SSH but my problem can be resolved manually via SSH as I said but in script it did not work. What am I going to do to make scp works without password?

Solution

If below scp command is being run on local_host,then you are trying to scp as local_user to local_host as local_user - ofcourse this would prompt for password, as you had only password less login for remote <-> local users only - not local <-> local

scp /home/${remote_user}/info.txt.gz ${local_user}@${local_host}:/root/

Comments

[Criveti Mihai]

TL;DR. Is your SSH key encrypted (ex: do you type in a password when using your key?). Are you using ssh-agent (or PuTTY Agent on Windows)?

[Eric Renouf]

You know you're executing that scp from the first host right, not from remote_host The only command you're execute on the remote host is netstat -tulpn everything else is on your first host

[David King]

Try adding the -vv flag on the scp command to see if it's even attempting to do key-based auth.

[fuser]

Criveti Mihai, yes I am using Putty Agent on Windows.

[gogoud]

First line of your script should be #!/bin/bash. Did you do all actions as root - or some as another user? I think your scp line last parameter should be ${remote_user}@${remote_host}:/root/ - assuming you really want to save the .gz file at remote's /root which seems a strange location.

[fuser]

I did all actions as root - FOR SURE! Such locations I had given only for example - because we can use in spite of them real host names and ip addresses.

[fuser]

#!/bin/bash it is just my blot. Thanks! I have corrected it.

[roaima]

Your code uses paths such as /home/${remote_user}/ on the local machine all over the place. Is that really intentional?

[fuser]

I tried to use what you said, mtk. Something like this sftp ${local_user}@${local_host} <<EOT put info.txt.tgz quit EOT inspite of scp command but it asked for password again

[ekoeppen]

@fuser some step would be missing. check this post to setup passwordless sftp stackoverflow.com/a/15808596/1135954

[fuser]

Why do I need to set up passwordless sftp If I have already had passwordless ssh?