Question: what ports are open by default?
Answer: 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)