To connect to a router running DD-WRT firmware perform following:

• Login into router’s web GUI as administrator
• Go to Services > Services and “Enable” SSHd under Secure Shell
  
  
• Go to Administration > Management and “Enable” SSH Management under Remote Access
  
  
• Connect to router’s IP address using your favourite SSH client (i.e. PUTTY) using username: root and password you normally use to login to the web admin GUI.