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.
SMTPPORT 587SMTP is used to send email.
MAILPORT 25MAIL is simply SMTP on a different port, typically not requiring authentication.