Setting up local domains on a LAN using a Synology NAS

Our goal is to access various resources on a LAN using custom domains such as dsm.homelab.lan (for accessing Synology DSM). We will use a Synology NAS for this, acting as an authoritative DNS server.

1. Install DNS Server on the Synology using Package Center.

2. Open it and create a primary zone. See the configuration below for homelab.lan. Simply replace the primary DNS server by your NAS IP.

   

   Figure 1: Configuration for the primary zone.

   DNS Server should have created the default records below.

   

   Figure 2: Default records for the zone.

   At this point we can already perform a few tests to make sure everything works as intended.

3. Add the NAS as your primary DNS server on your router. In my case, in the DHCP section of my router:

   

   Figure 3: Adding the NAS as a primary DNS server.

4. On one of your GNU/Linux machines (for Windows, you're on your own here 😇), refresh your DNS entries.

   sudo dhclient -r && sudo dhclient
   

   After this step, you should see your NAS IP in the resolv.conf file:

   cat /etc/resolv.conf
   

5. You should now be able to ping ns.homelab.lan, but not homelab.lan.

   ping -c 3 ns.homelab.lan && ping -c 3 homelab.lan
   

   > ping -c 3 ns.homelab.lan && ping -c 3 homelab.lan
   PING ns.homelab.lan (192.168.1.24) 56(84) bytes of data.
   64 bytes from 192.168.1.24: icmp_seq=1 ttl=64 time=1.95 ms
   64 bytes from 192.168.1.24: icmp_seq=2 ttl=64 time=4.95 ms
   64 bytes from 192.168.1.24: icmp_seq=3 ttl=64 time=5.78 ms
   
   --- ns.homelab.lan ping statistics ---
   3 packets transmitted, 3 received, 0% packet loss, time 2003ms
   rtt min/avg/max/mdev = 1.949/4.226/5.784/1.646 ms
   ping: homelab.lan: No address associated with hostname
   

   This is normal. However, you should be able to use the DNS lookup utility dig on both.

   dig ns.homelab.lan
   dig homelab.lan
   

6. Now let's add a DNS record for Synology DSM at dsm.homelab.lan. On the homelab.lan zone, click Edit > Resource record.

   

   Figure 4: Adding a new record to the zone.

   Click Create > A type and fill the dialog like this:

   

   Figure 5: Adding a new record to the zone.

   Save and finish. You should be able to access DSM in a browser by visiting http://dsm.homelab.lan/¹. However, your might see the port in the URL:

   

   Figure 6: Port is still visible in the URL.

7. To redirect a subdomain (like dsm.homelab.lan) to an IP + port, we need a reverse proxy. Click Control Panel > Login Portal > Advanced, and choose Reverse Proxy. Here you can associate a subdomain to a IP + port. In our case:

   

   Figure 7: Adding a reverse proxy entry for Synology DSM.

   The port should not appear anymore when you access http://dsm.homelab.lan/.

8. You can proceed like this for all your services: Docker containers on the NAS, on a Rasperry Pi, etc., as long as you can already access your resource using a local IP and a port.