nstack is a Linux userspace TCP/IP stack, contributed by Teacher Jserv and students in National Cheng Kung University. It can be useful in specific situations, such as communication among multiple virtual machines or experiments on TCP/IP stack. Current features including TCPv4 Handshake, UDP checksum, Ethernet frame handling, etc. I’ve contributed a Linux kernel-based random number generator, which can be used at generate TCP sequence number. And my recent research focuses on assessing performance and validating correctness of nstack applications. I will (1) show the difference between nstack and Linux native TCP/IP stack, such as performance and framework (2) demonstrate the applications of nstack if my topic is selected.