Are transaction always submitted to non-validator nodes?

Question

Reading the Polkadot docs, I've run into the following statement:

Validators should only run the Polkadot binary, and they should not listen on any port other than the configured p2p port.

So far, what I understand is that when someone submits a transaction, every network participant will have to validate the transaction, so It will eventually reach a validator node. So I was wondering, where does the Polkadot Chrome extension connect to if only the libp2p port is available? Are there sync nodes that only gossip transactions?

Answer 1

The statement you quoted represents a security measure. This is a recommended best-practice because validators are sensitive nodes and attack surfaces must be reduced as much as possible.

Theoretically speaking, there's nothing preventing a validator node having regular RPC methods exposed such that it can be used to submit transactions. However that would be considered a bad security practice.

PolkadotJS (which I assume is what you mean by Chrome extension) sends RPC calls to regular (non-validator) full nodes. By having its p2p port open, the validator will receive transactions via gossip.