Port Forwarding Overview
You can map an external IP address and port with an IP address and port in a private network. This mapping, called port forwarding, is supported on the MS-DPC, MS-100, MS-400, and MS-500 MultiServices PICS. Starting in Junos OS Release 17.4R1, port forwarding is also supported on the MS-MPC and MS-MIC.
Port forwarding allows the destination address and port of a packet to be changed to reach the correct host in a Network Address Translation (NAT) gateway. The translation facilitates reaching a host within a masqueraded, typically private, network, based on the port number on which the packet was received from the originating host. An example of this type of destination is the host of a public HTTP server within a private network. You can also configure port forwarding without translating a destination address. Port forwarding supports endpoint-independent mapping (EIM), endpoint-independent filltering (EIF), and address pooling paired (APP).
Port forwarding works only with the FTP application-level gateway (ALG), and has no support for technologies that offer IPv6 services over IPv4 infrastructure, such as IPv6 rapid deployment (6rd) and dual-stack lite (DS-Lite). Port forwarding supports only dnat-44 and twice-napt-44 on IPv4 networks.
Benefits of Port Forwarding
Allows remote computers, such as public machines on the Internet, to connect to a non-standard port of a specific computer that is hidden within a private network.