Port forwarding allows remote computers to pass data to a specific host or service within a private LAN by routing incoming internet traffic to specific devices. It uses the carrier assigned IP address plus a designated port number to access a specific device on the LAN. Port numbers are registered with the IANA and range from 0 to 49000. Many well-known port numbers used for services include 80 for HTTP, 21 for FTP, 443 for SSL, and 502 for Modbus TCP. The port numbers in the modem are configurable and will pass both TCP and UDP protocols when enabled. The choice of port number is usually based on the software application used to access the end device. A mobile terminated static IP provided by the carrier is recommended for port forwarding applications. Some carriers restrict predefined port number ranges on their network, therefore, it is suggested you check with the carrier before provisioning service. Please click here for instructions on configuring port forwarding rules in a Digi Transport Router.
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