SSHPORT 22SSH allows humans and bots to log into remote servers.
TNETPORT 23TELNET is an older protocol for logging into remote machines.
FTPPORT 21FTP is a legacy protocol, allowing files to be accessed remotely.
RDPPORT 3389RDP supports logging in with a virtual desktop (usually on Windows).
SMBPORT 445SMB is a remote file access protocol, introduced by Windows.
SIPPORT 5060SIP allows humans and bots to make phone calls.
MAILPORT 25MAIL is the SMTP protocol to send email.
SMTPPORT 587SMTP is this protocol on another port, sometimes requiring authentication.