SSHSSH allows humans and bots to log into remote servers. (port 22)
TNETTELNET is an older protocol for logging into remote machines. (port 23)
FTPFTP is a legacy protocol, allowing files to be accessed remotely. (port 21)
RDPRDP supports logging in with a virtual desktop, usually on Windows. (port 3389)
SMBSMB is a remote file access protocol, introduced by Windows. (port 445)
SIPSIP allows humans and bots to make phone calls. (port 5060)
HTTPHTTP is the web protocol, and bots probe it for exploitable apps and known vulnerabilities. (ports 80, 443)
SMTPSMTP is the email protocol, which bots exploit to relay spam across the net. (ports 25, 587)