Rsync with SSH prompting for remote password

Question

I have followed the following guide to setup Rsync with SSH between my local machine and a remote server:

I performed the below as root:

1. rsync -avz -e ssh /home/user/dir [email protected]::Backup/dir -> prompts for password

2. ssh-keygen -> Key generated

3. ssh-copy-id -i ~/.ssh/id_rsa.pub 192.168.200.10 -> confirmation that keys were copied

4. ssh 192.168.200.10 -> Accesses the remote server without promting for password

5. rsync -avz -e ssh /home/user/dir [email protected]::Backup/dir -> Prompts for password

Is it not strange that I can SSH into the remote server without being prompted for the password but do when using rsync?

I can see .ssh/authorized_keys on the remote server.

Where am I doing wrong?

Answer 1

You are mixing two separate connection modes: with a remote shell (-e ssh) and without a remote shell, thru a rsync daemon (identified by the double colon).

The manual states:

CONNECTING TO AN RSYNC SERVER

It is also possible to use rsync without a remote shell as the trans- port. In this case you will connect to a remote rsync server running on TCP port 873.

...... you either use a double colon :: instead of a single colon to separate the hostname from the path, or you use an rsync:// URL.

....... Some paths on the remote server may require authentication. If so then you will receive a password prompt when you connect. You can avoid the password prompt by setting the environment variable RSYNC_PASSWORD to the password you want to use or using the --password-file option. This may be useful when scripting rsync.

Probably the simplest way to obtain passwordless authentication for you is to modify the command above as follows:

   rsync -avz -e ssh /home/user/dir [email protected]:/absolute/path/to/Backup/dir

Answer 2

Your username on your local account is probably not root, which is the username you use with Rsync.

ssh remotehost

…is effectively the same as:

ssh localUserName@remotehost

---

Sorry, I didn't notice that you already said you’re running as root.

I also didn’t notice that you are using the module syntax with two colons (::) after the remote hostname. I don’t think the guide you followed covers connecting to Rsync this way, and that you should be fine if you use the single colon syntax, for example:

rsync -avz -e ssh /home/user/dir [email protected]:/some/path/backups/dir

Answer 3

I had this problem too - I hope this helps. For me, the problem was the syntax required for alternate port ssh. Here are two working examples:

Execute this from the target backup machine, which pulls from source to target backup:

rsync -av --delete -e 'ssh -p 59333 -i /home/user/.ssh/id_rsa' [email protected]:/home/user/Server/ /home/user/Server/

Execute this from the source machine, which sends from source to target backup:

rsync -av --delete -e 'ssh -p 59333 -i /home/user/.ssh/id_rsa' /home/user/Server/ [email protected]:/home/user/Server/

This solution assumes you already exchanged your public key with target and/or vice versa using ssh-copy-id -p 59333. This wonky syntax is not required if you use port 22, in which case you can use the i flag and it will procure the public key from the default location in ~/.ssh/id_rsa.pub. Here is an example without alternate port that also works fine:

Execute this from the target backup machine, which pulls from source to target backup:

sudo rsync -avi --delete [email protected]:/var/www/ /media/sdb1/backups/www/

Execute this from the source machine, which sends from source to target backup:

sudo rsync -avi --delete /media/sdb1/backups/www/ [email protected]:/var/www/

If you are still getting prompted for a password, then you need to check your ssh configuration in /etc/ssh/sshd_config and verify that the users in source and target each have the others' respective public ssh key. I left this amount of detail because the syntax left by two others above still does not work for me.