how to secure an vmware esxi host on a root server?

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http://serverfault.com – for me, a vmware machine normally has 2 lan interfaces, one connected with the lan or the management computer and the 2nd one connected with the wan interface for public access. so security is ensured by having a firewall in front of the "public network card" of vmware and only making it possible to access the managment interface over the "private network card". but how do i ensure security, if i install vmware esxi 5.0 on normal dedicated root server with multiple public ips, without a firewall in front of the server, without any (for me accessable) routing before the server, without multip (HowTos)