Raspberry Pi – Is running a Bitcoin node harmful to my local network?

This depends on the type of node you are running on.

Running a ‘full node’ (full archive node) should not increase your risk, as you do not need to configure your router to accept connections from other nodes on the network.

However, to support the network and run ‘listening nodes’ (supernodes), you will need to configure your router to forward inbound connections on the 8333 or run nodes over the tor network.

This may increase the risk for people trying to access other services running on the computer listening on port 8333. This can be mitigated by running the nodes on dedicated machines to minimize the attack surface. Configuring automatic security updates can also help.

Useful resources: