Techniques are described that enable users to configure the mirroring of network traffic sent to or received by computing resources associated with a virtual network of computing resources at a service provider network. The mirrored network traffic can be used for many different purposes including, for example, network traffic content inspection, forensic and threat analysis, network troubleshooting, data loss prevention, and the like. Users can configure such network traffic mirroring without the need to manually install and manage network capture agents or other such processes on each computing resource for which network traffic mirroring is desired. Users can cause mirrored network traffic to be stored at a storage service in the form of packet capture (or “pcap”) files, which can be used by any number of available out-of-band security and monitoring appliances including other user-specific monitoring tools and/or other services of the service provider network.