The online far right ecosystem is heterogeneous, dynamic, and complex, as is the online ecosystem about covid-19. These two ecosystems are intimately intertwined. I will discuss some of the features of each together with their connections, viewed through the lens of network science and data science. In particular, I will discuss a "sentinel node" approach for examining online structure of the far right and covid ecosystems, and use this approach to examine how covid misinformation propagates within and between communities.