@Override
    public void onRequest(ByteBuffer buffer) throws IOException {
        if (mRequestFinished) {
            mLog.w("Drop a buffer due to request has finished.");
            return;
        }
        resolvePolicyIfNecessary(buffer);
        if (mPolicy == POLICY_ALLOWED) {
            mGateway.onRequest(buffer);
        } else if (mPolicy == POLICY_DISALLOWED) {
            super.onRequest(buffer);
        }
    }
This policy doesn't allow data flow to configured virtual gateway.
netbare-core/src/main/java/com/github/megatronking/netbare/NetBareVirtualGateway.java