Tag: homelab

Building a homelab – local DNS

This is a second post in a series of my experiences while Building a Homelab. The first post focusing on the history, hardware, and OS can be found here.

Having a number of networked devices at home presents some management overhead. You may find yourself asking, what was the IP address of that one laptop? or just getting plain old tired of looking at IP addresses. One method people often use to manage their network is to assign Domain Name System (DNS) names to their devices. Instead of constantly typing in 192.168.1.1 you could instead assign it the domain name router.home. Entering router.home into your browser then transparently brings you to the same webpage as 192.168.1.1. This not only works for browsing the internet, services such as SSH, FTP, and other places where an IP address would normally be used can likely use the friendlier domain name instead.

So how can this be done? It’s actually quite simple given you have an always-on computer on the same network as the rest of your devices, a router with DNS serving capabilities, or even a DNS provider such as Cloudflare. This article will focus on the DIY solution of running a DNS server on an always on computer.

Before we get to how to set this up, let’s first explain what DNS is and how it works. Feel free to skip over this section if you’re already knowledgeable.

What is DNS?

DNS is a technology used to translate human-friendly domain names to IP addresses. For example, we can ask a DNS server what is the IP address for the domain google.com? The DNS server would then respond with the IP address for google.com: 172.217.1.174. DNS is used for almost every request your computer, phone, smart lightbulbs, and more when it communicates with the internet.

Anyone who runs a website is using DNS whether they know it or not. Usually the basic premise is that each domain name (eg. mysite.com) will have a DNS record which points to an IP address. The IP address is the actual computer on the internet which traffic for mysite.com will be sent to.

An example of DNS being used can be for jonsimpson.ca. This site is hosted on a server that I pay for at DigitalOcean. That server has an IP address of 1.2.3.4 (a fictitious example). I use Cloudflare as the DNS provider for jonsimpson.ca. Anytime a user’s browser wants to go to jonsimpson.ca, it uses DNS to figure out that jonsimpson.ca is located at 1.2.3.4, then the user’s browser opens up a connection with the server at 1.2.3.4 to load this site.

This is quite a simplified definition of DNS as the system is distributed across the world, hierarchical, and involves hundreds of thousands, if not millions, of different entities. Cloudflare provides a more detailed explanation as to how DNS works, and Wikipedia has comprehensive coverage of multiple concerns relating to DNS. But what was explained earlier will provide enough context for this article.

Running a local DNS server

If there’s an always-on computer – whether that’s a spare computer or Raspberry Pi – a DNS server can run on it and provide DNS capabilities for the local network. Dnsmasq is a lightweight but powerful DNS server that has been around for a long time. Many hobbyists use Dnsmasq for their home environments since it’s quite simple to configure and get going. One minimal text file is all that’s needed for configuring a functional DNS service.

I chose to run Dnsmasq on my always-on server in a Docker container. When configuring Dnsmasq, for each device that I wanted to provide a domain name for, I added a line in the configuration mapping its IP address to the name I wanted to give it. For example, my router which lives at 192.168.1.1 was assigned router.home.mysite.com, and my server which lives at 192.168.1.2 was assigned server.home.mysite.com.

I then configured my router’s DHCP to tell all clients to use the DNS provided by the server (contact 192.168.1.2 for DNS), and configure some manually networked devices to explicitly use the DNS provided by the server. Now on all of my devices I can type in server.home.mysite.com anywhere I would type 192.168.1.2 – so much nicer compared to having to type in an entire IP address.

nslookup and dig are both common command line tools to query the Domain Name System. They are often found already available on many Linux and Unix operating systems, or a straightforward install away. Using these tools can help with inspecting and debugging DNS setups. Here’s an example query using nslookup to find google.com:

$ nslookup google.com
Server:          192.168.1.2
Address:        192.168.1.2#53

Non-authoritative answer:
Name:   google.com
Address: 172.217.1.174

The first Server and Address denote the DNS server that was used to find the IP address for google.com. In this case, it was the Dnsmasq DNS server running on my home server. Name and Address at the bottom signify the actual response we’re interested in. In this case, 172.217.1.174 is the IP address I get whenever I go to google.com.

The configuration

I use Docker as a way to simplify the configuration and running of different services. Specifically, I use docker-compose to define the Dnsmasq Docker image to use, which ports should be opened, and where to find its configuration. Here’s the docker-compose.yml file I use:

The docker-compose file defines one dns service that uses the base image of strm/dnsmasq, as its one of the more popular Dnsmasq images available on hub.docker.com. The volume option specifies that we map a config file located alongside the docker-compose.yml file at config/dnsmasq.conf into the container’s filesystem at /etc/dnsmasq.conf. This is done to allow the container to be recreated at any time while keeping the same configuration. Networking-wise, TCP and UDP port 53 are exposed (yes, DNS operates over TCP sometimes). The network-mode is set to the host’s network (Dnsmasq just doesn’t work without this). And lastly, the NET_ADMIN capability so that we can use privileged ports below 1024. The last option restart, (one of my favourite features of docker-compose) is to keep the container running even when the host reboots or the container dies.

All of these docker-compose.yml options can be understood in more detail in Docker’s reference docs.

More importantly, here’s the dnsmasq.conf file I use to actually configure Dnsmasq’s DNS capabilities:

A lot of these settings were based off of the following blog post. Many of these options can be looked up online in the official documentation, therefore I will focus on the ones relevant to this article.

I have my Ubiquity router handle providing DHCP for my network, therefore the no-dhcp-interface=eno1 is set here to not provide any DHCP services to the local network, as eno1 is the interface my server uses to connect to the network.

When Dnsmasq needs to find the DNS record for something that it doesn’t know, it performs a request to an upstream DNS server. server is used for this and can be specified multiple times to provide redundancy in case one of these DNS servers are down. I’ve specified both the Google and Cloudflare DNS servers. In addition to this, the all-servers option results in all defined server entries being queried simultaneously. This has the benefit that one DNS server may respond quicker than the others, resulting a net-faster response to the DNS query.

The most important part of this dnsmasq.conf configuration file are the last lines defined in the file that start with address=. This is Dnsmasq’s way to declare DNS mappings. For example, any device on my network performing a request for server.home.mysite.com will have 192.168.1.2 returned.

The really cool thing with DNS is that subdomains for any of these records return the same IP, unless declared explicitly otherwise. An example of this is blog.apps.site.jonsimpson.ca doesn’t exist in the configuration file, but performing a DNS request for it will return 192.168.1.2. This has the effect that “multiple services” can each have its own domain name, but all be served by the same IP address.

Conclusion

Hopefully this article gives a background about what DNS is, how it can be useful in a home environment, and how to setup and operate a Dnsmasq DNS server. A future post will build on top of the DNS functionality that has been setup here to provide multiple HTTP services running on separate domain names, all served by the same server, for the home network to use.

Building a homelab – a walk through history and investing in new hardware

This is the first post in a series of my experiences while Building a Homelab. The second post focuses on setting up a local DNS server and can be found here.

I’ve had a particular interest in home computers and servers for a long time now. One of my experiences was wiring my childhood home up with CAT-5 ethernet to the rooms with TVs or computers and having them all connected to a 24 port 100 Mbps switch in the crawlspace. This was part of a master plan to provide different computers in the house with internet connection (when WiFi wasn’t as good as it is today), TVs with smart media boxes (think Apple TV, Roku, and the like but 10 years ago), and to tie it all together a home server for serving media storing files.

The magazine Maximum PC was a major source for this inspiration as they had a number of captivating DIY articles for running your own home server, media streaming devices, and home networking. The memory is a bit rough around the edges, but these projects happened around the same time and on my own dollar – all for the satisfaction of having a bleeding edge entertainment system.

Around this time Windows had a product out for a year called Windows Home Server. It was a OS which catered towards consumers and their home needs. Some of the features it had was network file shares for storing files, computer backup and restore, media sharing, and a number of extensions available from the community. I built a $400 box to run this OS and store two hard drives. The network switch in the crawlspace was a perfect place to put this headless server. Over many years this server was successfully used for computer backups, file storage, network bandwidth monitoring, and media serving to a number of PCs and media streaming boxes attached to TVs.

Two of the TVs in the house had these Western Digital TV Live boxes for playing media off of the network. These devices were quite basic at the time where only Youtube, Flickr, and a handful of other services were available – lacking Netflix and the other now popular Internet streaming services. Instead, they were primarily built for streaming media off of the local network – in this case off of the home server file share. My family and I were able to watch movies and TV shows from the comfort of our couch, and on-demand. This was crazy cool at the time as most people were still using physical media (DVD/Blu-ray) and streaming media had not taken off yet. I also vaguely remember hacking one of the boxes to put on a community-built firmware.

Windows Home Server was great at the time since it offered all of this functionality out of the box with simple configuration. I remember playing with BSD-based FreeNAS on old computers and being overwhelmed at all of the extra configuration needed to achieve something that you get out of the box with Windows Home Server. Additionally, the overhead of having to administer FreeNAS while only having a vague knowledge of Linux and BSD at the time wasn’t a selling point.

Now back to current times. I’m in the profession of software development, have been using various Linux distros for personal use on laptops and servers, and would now consider myself a sysadmin enthusiast. Living in my own place, I’ve been using my own Ubuntu-based laptop to run a Plex media server and stream content to my Roku Streaming Stick+ attached to my TV. The laptop’s 1 TB hard drive was filling up. It was also inconvenient to have this laptop constantly on for serving content.

Browsing Reddit, I came across r/homelab, a community of people interested in owning and managing servers for their own fun. Everything from datacenter server hardware to Raspberry PIs, networking, virtualization, operating systems, and applications. This subreddit gave me the idea of purchasing some decommissioned server hardware from eBay. I sat on the idea for a few months. Covid-19 eventually happened and with all my spare time I gave in to buying some hardware.

After a bunch of research on r/homelab about which servers are quiet, energy efficient, extendable, and will last a number of years, I settled on a Dell R520 with 2 x 6 cores at 2.4 Ghz, 48 GB DDR3 RAM, 2 x 1 Gbit NICs and 8 x 3.5″ hard drive bays. I bought a 1 TB SSD as the boot drive and a refurbished 10 TB hard drive for storing data.

The front of the Dell R520, showing the 8 3.5″ drive bays and some of the internals.

Since I intended on running the ZFS filesystem on the data drive, many people gave the heads up that the Host Bus Adaptor (HBA) card (a piece of hardware which connects the SAS/SATA hard drives and SSDs to the motherboard) comes with the default Dell firmware. This default firmware caters towards always running some sort of hardware-based RAID setup, thus hiding the SMART status of all drives. With ZFS, accessing the SMART data for each drive is paramount for data integrity. To get around this limitation with the included HBA card, the homelab community has some unofficial firmware for it which exposes IT mode, basically a way to pass through each drive to the OS – completely bypassing any hardware RAID functionality. Some breath holding later and the HBA card now had the new firmware.

I bought a separate HBA card with the knowledge at the time that the one that comes with the Dell R520 didn’t have any IT mode firmware from the community. I ended up being wrong after a whole lot of investigation. Thankfully I should be able to flash new firmware on this card as well and sell it back on eBay.

A Dell Perc H310 Mini Mono HBA (Host Bus Adaptor) used in Dell servers for interfacing between the motherboard and SAS/SATA drives.

As the hardware was all being figured out, I was also researching and playing with different hypervisors – an operating system made for running multiple operating systems on the same hardware. The homelab community often refers to VMware ESXi, Proxmox VE, and even Unraid. I sampled out the first two, as Unraid didn’t have an ISO available to test with and wasn’t free.

Going through the pain of making a USB stick bootable for an afternoon, I eventually got ESXi installing on the system. Poking around, it was interesting to see that VM storage was handled by having a physical disk formatted to a VMware format specific to storing multiple VMs – vmfs. With the goal of having one of the VMs have full control over a drive formatted with the ZFS filesystem, ESXi provides a feature called hardware passthrough which bypasses virtualization of the physical hardware. One big blocker for myself was the restriction on the free version which limits VMs to a maximum of 8 vCPUs – a waste of resources when having 12 CPUs and not enough VMs to utilize them.

Next, I took a look at Proxmox by loading it up as a VM on ESXi. It was Debian based, which was a plus as I’m comfortable with systemd and Ubuntu systems already. The Proxmox UI appeared like it had quite a few useful features, but didn’t feel like what I needed. I was much more comfortable with the terminal, and these graphical interfaces to manage things felt more like a limitation than a benefit. I could always SSH into Proxmox and manage things there, but there’s always the aspect of learning the intricacies of how this turnkey system was setup. Who knows what was default Debian configured and what was modified by Proxmox. Not to mention, what if Docker or other software was out of date and couldn’t be upgraded? This would be an unnecessary limitation I could avoid if rolling my own.

Lastly, I went back to my roots – Ubuntu Server. I spun up a VM of it on ESXi. Since I’m quite used to the way Ubuntu works it was comfortable knowing what I could do. There were no 8 vCPU limitations with Ubuntu Server as the host OS – I can utilize all of the server’s resources. After some thinking I realized I didn’t have any need to run any VMs at the moment. In the past I’ve managed a number of VMs using QEMU using Ubuntu Server, therefore if the need arises again I can pull it off. The reason why I’m not using any VMs is because I’m using Docker for all of my application needs. I already have a few apps running in Docker containers on my laptop that I’ll eventually transfer over to the server. Next up, ZFS on Linux has been available for a while now in Ubuntu, giving me the confidence that the data drive will be formatted with ZFS without a problem.

The internals of the Dell R520 with the thermal cover removed. Note the row of six fans across the width of the case to keep things cool.

In the end I scrapped the idea of running a hypervisor such as EXSi and running multiple VMs on top of it because my workloads all live in Docker containers instead. Ubuntu Server is more suitable since I am able to configure everything from a SSH console. If I may conjecture why the r/homelab community loves their VMs, it may be because many of the hobbyists are used to using them for their day-jobs. There were a handful of folks who did run their own GUI-less, no-VM setups, but it was the minority.

In the end, Ubuntu Server 20.04 LTS was installed on a 1 TB SSD boot drive. A 10 TB HDD was formatted with ZFS in a single drive configuration. Docker daemon was installed from its official Apt repo, and a number of other non-root processes were installed from Nix and Nixpkgs.

Conclusion

There’s a few more things I want to discuss regarding the home server. Some of those include using Nix and Nixpkgs in a server environment and some of the difficulties, setting up a local DNS server to provide domain name resolution for devices on the network and in Docker containers, a reverse proxy for the webapps running in Docker containers using the Caddy webserver, and some DataDog monitoring.

In the future I have plans to expand the amount of storage while at the same time introducing some redundancy with ZFS RAIDz1, diving into being able to remotely access the local network via VPN or some other secure method, and better monitoring for uptime, ZFS notifications, OS notifications, and the like.