Scp

To autenticate yourself to anither machine you can use keys. To generate a key pair use

ssh-keygen -t rsa

[root@server .ssh]# ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /root/.ssh/id_rsa.
Your public key has been saved in /root/.ssh/id_rsa.pub.
The key fingerprint is:

Now copy the key to the other machine

[root@server bin]$ scp /path/.ssh/id_rsa.pub remote_user@serverdomain.org:.ssh/authorized_keys

The user is now know on the other machine