On Dreamhost servers one finds many open ports,
$ nmap example.org Starting Nmap 4.68 ( http://nmap.org ) at 2008-10-09 07:18 CST Interesting ports on apache2-adamant.spyro.dreamhost.com (18.104.22.168): PORT STATE SERVICE 21/tcp open ftp 22/tcp open ssh 25/tcp open smtp 80/tcp open http
The above services are well known and understood, but
111/tcp filtered rpcbind 113/tcp open auth 548/tcp open afp 587/tcp open submission 691/tcp open resvc
perhaps are for a few of the websites on the shared server, thus all websites on the server will appear to have them open too, though not apparently a security risk...