# Gateway and OFR Requirements

The Optimized Fee Relay (OFR) is accessed through a gateway that is running as a docker container in the Solana node server. 

The gateway receives shreds through OFR by communicating with bloXroute's OFR Relay, which uses port `18888` by default.  Please make sure the following UDP ports are open:

| Port        | Direction | Description                                      |
| ----------- | --------- | ------------------------------------------------ |
| UDP – 18888 | Inbound   | Used by the gateway for communication with `OFR` |