A typical problem on networks is that someone setup a DHCP server by mistake, and the entire network goes down.
Is it possible in VMware to close for port 68 UDP for all clients?
That would ensure that no VM would be able to act as a DHCP server.
Perhaps VMware vShield can do this.. I'm not sure. The built in vSwitches can not filter traffic.
Either way - security measures like these are usually put in place at the edge network. Cisco switches can for example use DHCP snooping to filter and/or rate limit DHCP offers from untrusted switch ports. This implicates that you do not run your DHCP server on the same vmware hosts as the vm's you are trying to block.
I don't think so - I don't believe the vswitches have any packet filtering capability. Sounds like you might need to segregate and firewall your VM network from networks you don't have control over.