OppBSD is an effort to get the network stack of the actual FreeBSD kernel working in OMNeT++ as a simulation model. In the model, every simulated host (or router) runs its own copy of the FreeBSD kernel’s networking stack, and every host (or router) has its own copy of all state variables of the FreeBSD kernel. Presently, the package covers the full TCP/IP stack including ICMP, ARP, sockets and Ethernet frames. It also allows one to dump internal kernel variables of the tcp control block (e.g., windows sizes, ssthresh, etc.) into an OMNeT++ vector file for later analysis and also provides to dump pcap files for analysis with standard tools like tcpdump or WireShark (formerly known as Ethereal).