Unix - SSH/SCP

• Check SSH server running:
  

  # cat /etc/rc.conf | grep ssh
  sshd_enable="YES"



• SSH access to a remote machine:
  

  #/$ ssh username@remoteMachine

  
  'remoteMachine' is the DNS resolvable hostname of the remote host. IP address can also be used instead of the remote machine's hostname.


• Securely transfer file over SSH:
  

  #/$ scp -q -C -l 80000 username@remoteMachine:/home/username/test.txt \

  /home/username/. 



• Enable root access over SSH (only if it is essential):
  

  # vi /etc/ssh/sshd_config
  PermitRootLogin yes
  
  # service sshd restart  (or, # /etc/rc.d/sshd restart) 



• Generate and copy SSH keys:
  

  #/$ cd ~
  #/$ ssh-keygen -t rsa
  #/$ scp ~/.ssh/id_rsa.pub remoteMachine:.ssh/authorized_keys 

  
  'RSA' is used here as authentication mechanism. Similarly 'DSA' can also be used.


• Verify whether SSH key is working:
  

  #/$ ssh remoteMachine hostname

  
  Displays remote machine's hostname without a password prompt.


• Monitoring/tracing SSH/SCP activities:
  

  # cat /var/log/auth.log

  Displays detailed log.

Note: Unix commands and file locations used here have been tested on FreeBSD systems.