Here’s a chunk from the new edition of Networking for Systems Administrators.
Through your career, people have repeatedly blamed “the firewall.” The word firewall dates from the 1980s, when the concept of network-level access control was both exotic and bizarre. In the last fifty years, access controls have become broader and more complex. Some controls remained in the devices arbitrarily labeled “firewalls,” while others migrated to routers and switches and other devices. What does the word “firewall” mean today?
Like the words “computer” and “security,” it means nothing. Nothing.
Every layer of the network supports access controls. Any of these controls might trouble you. Proxies, network address translation (NAT, see Chapter 3) devices, packet filters (Chapter 5), protocol content filters, all of these can reasonably be called “firewalls.” Your network might have a device that gets called “the firewall,” but any organization’s network has multiple access controls.
The truth is, if I was willing to just slam out a chapter on TLS and X.509, and cut the stuff on 10/100 Ethernet, I’d have a first draft of this book by next week. But nooo, I have to be all stupid and ethical and painstakingly go through the entire book to be sure it’s the best, most up-to-date work I can create. You could support me by sponsoring the book. 16 more print sponsors and I do another challenge coin.