what ports are open by default?
['20 – FTP (File Transfer Protocol)', '22 – Secure Shell (SSH)', '25 – Simple Mail Transfer Protocol (SMTP)', '53 – Domain Name System (DNS)', '80 – Hypertext Transfer Protocol (HTTP)', '110 – Post Office Protocol (POP3)', '143 – Internet Message Access Protocol (IMAP)', '443 – HTTP Secure (HTTPS)']