ssh

Server configuration
    
[/etc/ssh/sshd_config]
SyslogFacility AUTHPRIV
PasswordAuthentication yes
ChallengeResponseAuthentication no
GSSAPIAuthentication yes
UsePAM yes
X11Forwarding yes
Subsystem       sftp    /usr/libexec/openssh/sftp-server
 
Client server automatic connection
You need an ssh-agent running on your client
Go home

Concept
The file authorized_keys contains the keys list. It may be copied among all servers

server>cd; mkdir .ssh; cd .ssh; touch authorized_keys

Issue this command, when prompted for password press enter twice
#DO NOT OVERWRITE AN EXISTING KEY; ANSWER NO!
client>cd; cd .ssh; ssh-keygen -t rsa; ssh-keygen -t dsa

Enter file in which to save the key(/home/oracle/.ssh/id_rsa): 
Created directory '/home/oracle/.ssh'.
Generating public/private rsa key pair.
Enter passphrase(empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /home/oracle/.ssh/id_rsa.
Your public key has been saved in /home/oracle/.ssh/id_rsa.pub.
The key fingerprint is:
md5 1024 9f:a8:d5:85:51:aa:de:b1:7d:f9:b7:d7:ac:1b:a5:73 oracle@db017ops

client>
  scp $HOME/.ssh/id_rsa.pub oracle@server:/home/oracle/.ssh/id_rsa.pub.tmp
  #Copy and paste the two lines separately
  scp $HOME/.ssh/id_dsa.pub oracle@server:/home/oracle/.ssh/id_dsa.pub.tmp
oracle@db035ops's password: 
id_rsa.pub           100% |*********************************************************************************|   225       00:00    

server>cd; cd .ssh; cat id_rsa.pub.tmp >> authorized_keys; cat id_dsa.pub.tmp >> authorized_keys; rm id_*sa.pub.tmp

Testing
#Do not skip testing, you need to answer "yes" when prompted for new host addition
client> ssh linuxes1 "date;hostname"

Resulting authorized_keys example
ssh-rsa AAA...uantc= oracle@node1.fadalti.com
ssh-dss AAAA...vsHIA== oracle@node1.fadalti.com
 
UNTESTED USER EQUIVALENCE POST PROCESS
exec /usr/bin/ssh-agent $SHELL
/usr/bin/ssh-add