10.8 Looking Forward
If you’re interested in getting your hands dirty with some complicated network servers, some very common ones are the Apache or nginx web servers and the Postfix email server. In particular, web servers are easy to install and most distributions supply packages. If your machine is behind a firewall or NAT-enabled router, you can experiment with the configuration as much as you’d like without worrying about security.
Throughout the last few chapters, we’ve been gradually moving from kernel space into user space. Only a few utilities discussed in this chapter, such as tcpdump, interact with the kernel. The remainder of this chapter describes how sockets bridge the gap between the kernel’s transport layer and the user-space application layer. It’s more advanced material, of particular interest to programmers, so feel free to skip to the next chapter if you like.