def test_ssh(host, username, password):
    ssh = paramiko.SSHClient()
    ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
    ssh.connect(host, username=username, password=password)

ssh: Could not resolve hostname localhost: Name or service not known

import socket
socket.getaddrinfo('google.com', None)
socket.getaddrinfo('localhost', None)