Ssh

From Cheatsheet

login without password

CLIENT ---------> SERVER

on CLIENT generate public key, id_dsa.pub so you can establish a link based on dsa encryption

 ssh-keygen -t dsa -f ~/.ssh/id_dsa -C "yourusername@clients_IP_or_hostname.com"
 cat ~/.ssh/id_dsa.pub | ssh yourusername@servers_IP_or_hostname.com 'cat - >> ~/.ssh/authorized_keys'

now try to login to the server from your client

 ssh yourusername@servers_IP_or_hostname.com

you should get a prompt for a passphrase, then it should log you in. Now logout to get back to your client

 ssh-agent bash
 ssh-add

it will ask you for your passphrase, enter it. Now try to login to the remote host, it should let you in with no password

 ssh yourusername@servers_IP_or_hostname.com

it should just log you in

keep ssh from logging you out

 vi /etc/ssh/sshd_config
   ClientAliveInterval 1500
 apt-get install screen
 screen (start screen)
 ctrl-A c (create new screen inside current screen session)
 ctrl-A n (go to next screen inside screen session)
 ctrl-A p (go to previous screen inside screen session)
 ctrl-A K (kill the current session you're in, exit also works)
 ctrl-A H (log all the stuff you do in screen)
 screen -ls (shows current screen sessions, example: 31619.ttyp2.gigan)
 screen -r 31619.ttyp2.gigan (re-attach to screen session)
 echo $TERM (shows you if this session is inside screen)

you can use

 nohup ./scriptname.sh & 

to run a script in the background and keep it running if ssh logs you out, but you can't re-attach to that console to see what it's doing, you just have to rely on the log files.

 [reference http://www.rackaid.com/resources/linux-tutorials/general-tutorials/using-screen/]