Using a Raspberry Pi for basic network services, Part 4: DNS server

Photo credit: Michael Henzler
Wikimedia Commons, CC BY-SA 4.0

The Raspberry Pi for basic Networking services series:

• Part 1: Introduction
• Part 2: DHCP server
• Part 3: Static IP addresses
• Part 4: DNS

In previous articles, I described how to set up a Raspberry Pi computer to act as a DHCP server and how to configure it to serve static IP addresses. But this is only half of the solution.

If all your computers are only used to access Internet sites, then you may not need anything more, but if you run any services on your LAN, you will want to access them as well as Internet services. Some examples of services I run on my LAN include:

• Printer. My printer has a built-in Ethernet interface and acts as a print server for the entire LAN.
• Web server. Two of my computers are running web server software. I use these for documents that I want to make available to all the computers in my home. In the past, when I ran an Internet-accessible web site, I used my local web servers as a staging area for changes before uploading them to the main server.
• File servers. Several of my computers have file sharing enabled so I can copy files between my computers.
• Remote access. Several computers run different remote access tools including SSH, VNC, X2Go and others. This lets me access everything from anywhere in the house.

When accessing a remote service, you need to provide the machine's name or IP address. If you've got a small LAN, you can just type in the address. Or you can set up hosts files on your computers to assign names to the addresses. But once you get more than a trivial number of devices on your network, those two solutions quickly become unmanageable. As I wrote in part 1, I've got 26 active devices on my LAN and many more that are rarely used. Using hosts files really doesn't work because every computer needs to be updated whenever the content changes and some devices (especially embedded devices like set-top boxes and mobile phones) don't even have a hosts file that can be managed.

But there is a well-established solution to the problem. The solution is to use the DNS protocol.

Using a Raspberry Pi for basic network services, Part 3: Static IP addresses

Photo credit: Michael Henzler
Wikimedia Commons, CC BY-SA 4.0

The Raspberry Pi for basic Networking services series:

• Part 1: Introduction
• Part 2: DHCP server
• Part 3: Static IP addresses
• Part 4: DNS

In part 2 of this series, I described how to set up a DHCP server on a Raspberry Pi so it can allocate and serve dynamic IP addresses. But sometimes you need a static address, where a given device always gets the same well-known address.

One obvious solution is to just disable the DHCP client on the device and manually configure its IP address and other networking credentials. This works well for many devices, especially desktop and laptop computers, but it is not without problems.

Using a Raspberry Pi for basic network services, Part 2: DHCP Server

Photo credit: Michael Henzler
Wikimedia Commons, CC BY-SA 4.0

The Raspberry Pi for basic Networking services series:

• Part 1: Introduction
• Part 2: DHCP server
• Part 3: Static IP addresses
• Part 4: DNS

Every computer on a LAN needs an IP address in order to communicate with anything else. While you can manually configure each device with a hard-coded ("static") address, this can be inconvenient and sometimes difficult. Especially for small IoT devices like smart appliances.

A long time ago, in the 1980's, several different technologies were invented so devices could be configured from a centralized location, without needing explicit on-device configuration of IP addresses and related information. The DHCP protocol was invented in 1993 and remains the most common mechanism in use today.

Yet another reason I don't like consumer networking gear

As those who know me in real life (and those who have been reading between the lines on this blog) know, I am a network professional. I develop software for commercial networking equipment. The really good stuff that phone companies use to make their networks work. So, in addition to having a healthy respect for how complicated a networking problem can get, I've also come to expect a certain level of quality in the equipment I use. Unfortunately, I can't afford to install commercial routing gear in my home. It costs too much, uses too much electricity, generates too much heat, etc.

So, for my home LAN, I use consumer gear like everybody else. Right now, this consists of a Zoom cable-modem/router, two Linksys routers in bridge mode (acting as Wi-Fi access points), and three powerline network adapters to connect them all.

Getting internet working in our new home

We just moved to a new home a few weeks ago. Unfortunately, Verizon FiOS is not available in the new neighborhood. The next town over is just getting wired now, but that’s there, not here. Rumors of local political problems between the town government and Verizon tells me that although FiOS might be available in 6 months, it’s also possible that it won’t be here for 6 years or 60 years. Needless to say, transferring the FiOS service from our old house was not an option. Verizon’s only internet offering for this location is DSL, which isn’t sufficient for my needs (telecommuting, including VoIP through our corporate VPN.)

For TV service, we subscribed to Dish Network. Mostly because the previous owners used it and the dish was already on the roof. That installed quickly and after three weeks I’m quite happy with it. But that’s for TV only. Dish does offer satellite internet service, but the latency inherent in a geostationary satellite link (over half-second round-trip packet times) makes it useless for interactive services like remote-logins and VoIP. Since both my wife and I require interactive services (distance learning, telecommuting, FaceTime, etc.) satellite internet is a no-go.

Which leaves Comcast internet as the only possibility for high bandwidth and low latency. We subscribed to their 25Mbps internet-only service. Due to the fact that we were involved with moving and closing on two houses (buying the new home and selling the old one), I was in no state of mind to research and buy a modem, I elected to rent Comcast’s modem, at least for the first few months, just to keep it simple.

Ericsson Technology: An attempt to motivate and clarify Software-Defined Networking (SDN)

From the YouTube description:

This tech talk is a guest keynote given at Ericsson Research by Scott Shenker, Professor at the University of California in Berkeley, Vice President of the International Computer Science Institute, and co- founder of Nicira Networks. Scott discusses the intellectual and practical weakness of today's foundations of networking, and argues that they can be strengthened by introducing cleaner abstractions, rather than managing the ever-growing complexity of protocols. Software-Defined Networking (SDN) is an instantiation of such abstractions that promises to create a more evolvable architecture for the Internet.

If you're into networking or computer-science theory, you will find this fascinating.