Server_B가 Server_A를 trust하도록 설정하면, Server_A 에서 Server_B로의 ssh, scp
등에 대해 패스워드 입력없이 진행 가능합니다.
Server_B와 Server_A 간에 양방향으로 trust관계를 성립하려면,
아래 Server_B trust Server_A configuration을 양쪽서버 두에서 작업하시면 됩니다.

* Server_B trust Server_A configuration

1. Server_B : /etc/ssh/sshd_config 주석제거
--------------------------------------------------------------------------------
HostKey /etc/ssh/ssh_host_rsa_key
HostKey /etc/ssh/ssh_host_dsa_key

RSAAuthentication yes
PubkeyAuthentication yes
AuthorizedKeysFile      .ssh/authorized_keys

PasswordAuthentication yes
--------------------------------------------------------------------------------

2. Server_B : sshd 재시작
# service sshd restart

3. Server_A : dsa key 생성
# /usr/bin/ssh-keygen -t dsa
--------------------------------------------------------------------------------
Generating public/private dsa key pair.
Enter file in which to save the key (/home/hyukjoo/.ssh/id_dsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/hyukjoo/.ssh/id_dsa.
Your public key has been saved in /home/hyukjoo/.ssh/id_dsa.pub.
The key fingerprint is:
67:3c:3f:cc:5f:00:1e:4b:3d:9e:a9:4f:46:be:9f:ad hyukjoo@Server_A
--------------------------------------------------------------------------------

4. Server_A : Server_B로 dsa key 복사
# scp .ssh/id_dsa.pub hyukjoo@Server_B:

5. Server_B : 복사된 dsa key 를 authorized_keys 에 등록
# cat id_dsa.pub > .ssh/authorized_keys

6. Server_B : 퍼미션 변경및 dsa파일 제거.
# rm -f id_dsa.pub
# chmod 700 .ssh
# chmod 744 .ssh/authorized_keys

7. 테스트
 - Server_A 에서 ssh를 통해 Server_B로 접속
# ssh Server_B

 - scp이용한 Server_A 에서 Server_B의 hyukjoo 계정 홈디렉토리로 filename.txt 복사
# scp filename.txt hyukjoo@Server_B: