nowadays most of the LAN networks use NAT to link all the computers to the internet using only one External IP address. what if have only one computer and i want it to use that external ip address directly on it's interface without using NAT, PAT and PortForwarding as it's nowadays done for global IPV6 adddresses ??? how it can be technically done ??? is there additional devices that should be present to implement this solution or should the router be replaced by another equipment ???

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    It is very simple to connect to the internet without nat... put a firewall like a Cisco ASA in transparent mode and connect to the upstream ISP's CPE. Technically you don't need a firewall, but no person in their right mind should connect a PC directly to the internet without knowing what they're doing and all the associated risks. – Mike Pennington Mar 30 '14 at 1:55
  • @MikePennington the firewall could do the filtering with policies, without doing NAT. For example: you have a public IP configured in the LAN. The firewall has the routing and filtering task, but not the NATting. – Bulki Mar 31 '14 at 10:31
  • @Bulki, I gave him a generic answer that works for many situations... of course, you could implement Topology C that was suggested below... that's basically what you're saying. I never said that my answer was the only answer :-) – Mike Pennington Mar 31 '14 at 10:39

IPv4 or IPv6 doesn't matter, except for the availability of addresses. These are examples using IPv4.

Topology A is what most people do. Topology B is what Mike Pennington said. Topology C is what you can do if you get a few addresses from your ISP.

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  • Note that for IPv6 toplogy "C" is the norm since IPv6 addresses are not in short supply and IPv6 proponents see NAT as highly undesirable. – Peter Green Jan 5 '17 at 14:17

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