The hosts.allow and hosts.deny files only affect incoming connections to services that read them (whether by being invoked through tcpd, or by otherwise using l

The hosts.allow and hosts.deny files only affect incoming connections to services that read them (whether by being invoked through tcpd, or by otherwise using libwrap. You could prevent Twitter from connecting to your FTP service or whatever, but not prevent other users on your network from contacting Twitter.