ok, guys. I cannot control sshd service on my rhel 5.6
i have two pc , one is client and the other is server.
i wanna write a bash script for increment backup some files on my client and then send the log file to server.
Let me show you guys what i have done :

Client
1: ssh-keygen
2:ssh-copy-id -i ~/.ssh/id_rsa.pub server

and then
scp -B /home/jack/* $SERVER:/tmp/
Address 192.168.4.171 maps to server171.com, but this does not map back to the address - POSSIBLE BREAK-IN ATTEMPT!
Permission denied (publickey,gssapi-with-mic,password).
lost connection

please help me . Thanks so much

Follow the below mentioned steps to enable the ssh/sftp connectivity

1)
Command : ssh-keygen -b 1024 -t <rsa (or) dsa> : This is create a key pair public/private keys.

User Home Dir Perm : 755
.ssh Dir Perm : 700
Public Key File Perm : 644 (or) 640
Private Key File Perm : 600

2) Users Public key needs to be appended in the authorized_keys2 file , This file has to be created if not available inside the .ssh dir.

authorized_keys2 File perm : 644

Similarly remote system Home Dir / .ssh dir and public/private and authorized_keys2 file should also have this permission. Kindly let me know if you need any more details.

thanks your reply. but the first command didnot work in my rhel: ssh-keygen -b 1024 -t rsa