Configure secure shell – SSH (step 1) – Linux/Unix

Owned by KrupeshD (Deactivated)
Last updated: Dec 27, 2012Version comment
4 min read

This step can be skipped, if a SSH without a password or passphrase is already configured.Secure shell is the preferred method to transport the Oracle logs from the primary to the standby servers.It is recommended to setup secure shell. However, if remote shell is preferred please see Appendix B – Configure remote shell (rsh).To configure SSH without using a password or passphrase the utility ssh-keygen is run. You have to create a RSA authentication key to be able to log into a remote site from your account. This should be done as the Dbvisit Standby software owner, never as root!

Important:
Ensure the home directories (cd $HOME) of the accounts on the primary and standby servers have the following permissions:

 

[oracle@avisit01]$ ls -al .
drwxr-xr-x 40 oracle dba 4096 Sep 17 02:46

If the permissions are 775 or 777 then ssh may keep asking for a password. Change permission with: chmod 755 .

1. On the primary server as Dbvisit Standby software owner (do not enter passphrase!):

 

[oracle@avisit01]$ ssh-keygen 
Generating public/private dsa key pair. 
Enter file in which to save the key (/oracle/orabase/.ssh/id_dsa): 
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /oracle/orabase/.ssh/id_dsa. 
Your public key has been saved in /oracle/orabase/.ssh/id_dsa.pub. 
The key fingerprint is: 
73:c7:f5:7c:ee:bd:62:7f:0d:51:ed:8a:c7:45:f7:d9 oracle@avisit01
*In this example avisit01 is the primary server and avisit03 is the standby server.
The public/private key pair may either be dsa or rsa
On some implementation of ssh, you have to specify: ssh-keygen -t dsa

 

On Linux the output may be different:

[oracle@avisit01]$ ssh-keygen 
Generating public/private rsa key pair. 
Enter file in which to save the key (/oracle/orabase/.ssh/identity): 
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /oracle/orabase/.ssh/identity. 
Your public key has been saved in /oracle/orabase/.ssh/identity.pub. 
The key fingerprint is: 
a2:88:ad:53:e8:5b:37:a1:82:6d:03:ec:96:c4:6b:df oracle@avisit01
*In this example avisit01 is the primary server and avisit03 is the standby server.
This will generate 2 files under your home directory: .ssh/id_dsa and .ssh/id_dsa.pub
Or generate the following files under your home directory: ssh/id_rsa and .ssh/id_rsa.pub

On Linux the files may be called different: .ssh/identity and .ssh/identity.pub

2. On the standby server as Dbvisit Standby software owner (do not enter passphrase!):

 

[oracle@avisit03]$ ssh-keygen 
Generating public/private dsa key pair. 
Enter file in which to save the key (/oracle/orabase/.ssh/id_dsa): 
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /oracle/orabase/.ssh/id_dsa. 
Your public key has been saved in /oracle/orabase/.ssh/id_dsa.pub. 
The key fingerprint is: 
73:c7:f5:7c:ee:bd:62:7f:0d:51:ed:8a:c7:45:f7:d9 oracle@avisit03
*In this example avisit01 is the primary server and avisit03 is the standby server.
The public/private key pair may either be dsa or rsa

 

On Linux the output may be different:

[oracle@avisit03]$ ssh-keygen 
Generating public/private rsa key pair. 
Enter file in which to save the key (/oracle/orabase/.ssh/identity): 
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /oracle/orabase/.ssh/identity. 
Your public key has been saved in /oracle/orabase/.ssh/identity.pub. 
The key fingerprint is: 
a2:88:ad:53:e8:5b:37:a1:82:6d:03:ec:96:c4:6b:df oracle@avisit03
*In this example avisit01 is the primary server and avisit03 is the standby server.

This will generate 2 files under your home directory: .ssh/id_dsa and .ssh/id_dsa.pub Or generate the following files under your home directory: .ssh/id_rsa and .ssh/id_rsa.pub

On Linuxt he files may be called different: .ssh/identity and .ssh/identity.pub

3. On the standby server create a new empty file called .ssh/authorized_keys

 

[oracle@avisit03]$ cd .ssh 
[oracle@avisit03]$ vi authorized_keys
*In this example avisit01 is the primary server and avisit03 is the standby server.

4. Copy the contents of file .ssh/id_dsa.pub from the primary server to the new file .ssh/authorized_keys on the standby server. The file may be called identity.pub or id_rsa.pub instead of id_dsa.pub.

 

[oracle@avisit01]$ cat id_dsa.pub 
ssh-dss AAAAB3NzaC1kc3MAAACBALj5RhJzSDOvRnTID/P2kblmE9qM2zCrzUa0gDL/fbngdcB8EELeJJi 
LuhR9uM/XyQr+UySGVeMS1jM0uBfQcs/7p3WAEkxncXzGduxlsyO8iyYfr8Kf7ufGPdJq7n15v0hjUMWSa 
w6YcA== oracle@avisit01

5. Ensure the new file .ssh/authorized_keys has the correct permission:

 

[oracle@avisit01]$ chmod 600 authorized_keys

6. On the primary server create a new empty file called .ssh/authorized_keys

 

[oracle@avisit01]$ cd .ssh 
[oracle@avisit01]$ vi authorized_keys
*In this example avisit01 is the primary server and avisit03 is the standby server

7. Copy the contents of file .ssh/id_dsa.pub from the standby server to the new file .ssh/authorized_keys on the primary server. The file may be called identity.pub or id_rsa.pub instead of id_dsa.pub.

 

[oracle@avisit03]$ cat id_dsa.pub 
ssh-dss AAAAB3NzaC1kc3MAAACBALj5RhJzSDOvRnTID/P2kblmE9qM2zCrzUa0gDL/fbngdcB8EELeJJi 
LuhR9uM/XyQr+UySGVeMS1jM0uBfQcs/7p3WAEkxncXzGduxlsyO8iyYfr8Kf7ufGPdJq7n15v0hjUMWSa 
w6YcA== oracle@avisit03

8. Ensure the new file .ssh/authorized_keys has the correct permission:

 

[oracle@avisit01]$ chmod 600 authorized_keys

SSH is now setup and configured. To test:

On the primary server:

 

[oracle@avisit03]$ ssh avisit03 ls -al 
The authenticity of host 'avisit03 (10.1.1.82)' can't be established. 
RSA key fingerprint is 40:bb:ea:96:48:7d:22:fa:36:a6:8e:e7:37:7c:f4:d3. 
Are you sure you want to continue connecting (yes/no)? yes 
Warning: Permanently added 'avisit03,10.1.1.82' (RSA) to the list of known hosts. 
total 896 
drwxr-xr-x 26 oracle dba 4096 Feb 27 18:49 . 
drwxr-xr-x 6 root root 4096 May 30 2006 .. 
rw------ 1 oracle dba 2640 Feb 15 09:39 .ICEauthority 
drwx------ 5 oracle dba 4096 May 21 2006 .Trash 
rw------ 1 oracle dba 120 Feb 15 09:39 .Xauthority 
rw-rr- 1 oracle dba 76 May 24 2006 .alias 
rw------ 1 oracle dba 16019 Jun 1 2006 .bash_history 
… 
…
*In this example avisit01 is the primary server and avisit03 is the standby server

On the standby server:

 

[oracle@avisit03]$ ssh avisit01 ls -al 
The authenticity of host 'avisit01 (10.1.1.81)' can't be established. 
RSA key fingerprint is 40:bb:ea:96:48:7d:22:fa:36:a6:8e:e7:37:7c:f4:d3. 
Are you sure you want to continue connecting (yes/no)? yes 
Warning: Permanently added 'avisit01,10.1.1.81' (RSA) to the list of known hosts. 
total 896 
drwxr-xr-x 26 oracle dba 4096 Feb 27 18:49 . 
drwxr-xr-x 6 root root 4096 May 30 2006 .. 
rw------ 1 oracle dba 2640 Feb 15 09:39 .ICEauthority 
drwx------ 5 oracle dba 4096 May 21 2006 .Trash 
rw------ 1 oracle dba 120 Feb 15 09:39 .Xauthority 
rw-rr- 1 oracle dba 76 May 24 2006 .alias 
rw------ 1 oracle dba 16019 Jun 1 2006 .bash_history 
… 
…
*In this example avisit01 is the primary server and avisit03 is the standby server

Secure shell configuration is now competed.

For more information on SSH, please consult the man pages in Unix or Linux.