Avoid entering the password (SCP without password) when using SCP for remote data transmission)

Assume that the local machine is client and the remote machine is server.
For example, copy/usr/A from the logged-on client (192.168.1.1) to the/usr directory of server (192.168.1.2,
The command is as follows:
SCP-r/usr/A root@192.168.1.2:/usr
Enter the server password and wait for a moment,
After entering the correct password,
Start copying all files under directory A to the server.
If you just copy an object,
The-R parameter is removed, for example:
SCP/usr/A/index.html root@192.168.1.2:/use//
You will find that using commands is a very convenient and quick way. However, if you do not want to enter a password, you need to establish a trust relationship between the two machines.

To establish a security trust relationship between the root of the client and the root of the server:
1. Run the ssh-keygen command on the client to generate a certificate that establishes a security trust relationship.
[Root @ client root] # ssh-keygen-B 1024-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): <-- press ENTER
Enter same passphrase again: <-- press ENTER
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:
49: 9C: 8A: 8f: BC: 19: 5E: 8c: C0: 10: D3: 15: 60: A3: 32: 1C root @ Client
[Root @ client root] #
Note: When the program prompts you to enter passphrase, enter the carriage return, indicating no certificate password.
The above command generates the Private Key Certificate id_rsa and Public Key Certificate id_rsa.pub, which are stored in the/root/. Ssh/subdirectory.
2. copy the Public Key Certificate id_rsa.pub to/root/of the server /. in the ssh/subdirectory, if the/root /. if no authorized_keys exists in SSH/, rename id_rsa.pub to authorized_keys /. if the authorized_keys file already exists in SSH/, add the id_rsa.pub content to the end of the authorized_keys file. [You can use the cat id_dsa.pub> authorized_keys command, or use Vim to open authorized_keys for compilation.]
3. Now we can use SCP for remote data transmission and avoid entering a password.

From: http://blog.csdn.net/dupei/article/details/6177538