service-and-banner

nmap -sV target.com
nc target.com 80
telnet target.com 80
whatweb target.com
curl -I http://target.com
wapplazyer http://target.com
echo | nc -nv -w 2 target.com 21

Using Python Socket

import socket
s = socket.socket()
s.connect(("target.com", 80))
s.send(b"HEAD / HTTP/1.1\r\nHost: target.com\r\n\r\n")
print(s.recv(1024))