import paramiko

client = paramiko.SSHClient()
client.load_system_host_keys()
client.set_missing_host_key_policy(paramiko.WarningPolicy())

server_add = "127.0.0.1"
username = "yyy"
password = "xxx"

client.connect(server_add, port=22, username= username, password= password)

stdin, stdout, stderr = client.exec_command("ls")

print stdout.read()