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loopback 3 you might be looking for this:
Loopback (also: loop-back) is often used for testing purposes, and refers to the process of routing packets back to their source without processing or modification. An operating system's virtual loopback interface can be used by network applications when sending data to the same machine. The IPv4 address space 127.0.0.0/8 and the IPv6 address ::1/128 are reserved for loopback interfaces, and the most common IPv4 address is 127.0.0.1.
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