The figure belоw illustrаtes аn IPsec cоnfigurаtiоn in the tunnel mode with ESP, in which the IPsec gateways are located at R1 and R2. The IP addresses of H1, H2, R1, and R2 are 172.16.1.10, 172.16.2.20, 200.168.1.100, and 193.68.2.23, respectively. H1 sends an IP datagram to H2. After R1 finishes processing the datagram and forwards it to the next hop, what are the source and destination IP addresses?