Sorry. I wrote it for my notes and wasn't necessarily polished for external use.

The basic gist of it is:

1. Reserve your IP range

2. Create the docker network (compatible with MACVLANs)

3. Create the macvlan on your Synology

4. Set up your container with the new network

You shouldn't have conflicts with the DSM ngnix after setting up a macvlan on a Synology.

Saying that, there are a few more steps you have to do to get it working. I've done it successfully on my Synology. Here is a guide I wrote for traefik in my notes. Also see the references for additional explanations.

I apologize for the formatting. I am on my phone.

Introduction

Long story short, Traefik uses ports 80 and 440. On the Synology NAS (from DSM 7 and upwards), those ports are occupied by the OS. There are two options to solve this issue:

Reroute all traffic on 80 and 443 on the router to a new port

Pros: no need for a VLAN (see 2.). Cons: need to expose all services on the Synology via Traefik Create a MAC VLAN + bridge, attach the docker container to it and assign an IP

Pros: Cleaner approach as the docker container gets assigned a new IP Cons: More complicated

This guide will discuss option 2.

Preparation

IP Reservation

Before we begin, some ip configuration is necessary. First you must configure any DHCP service on your network such that it will not assign addresses in a given range. This guide assumes you already have your raspberry pi set up as your DHCP service (and turned DHCP off in your router). Go to your pi-hole admin page and go to settings→DHCP.

Figure: DHCP Settings on the Pi-Hole

Here an IP range of 192.168.2.50-192.168.2.199 has been reserved by the pi-hole to be assigned. This leaves addresses 192.168.2.2-192.168.2.49 and 192.168.2.200-192.168.2.254 to us to use. I shall use the tail end of the range 192.168.2.200-192.168.2.254.

MACVLANs

The following is specifically for those that have a Synology NAS with a single ethernet port. This port should be designated eth0. To be sure, check using the following command:

ip link show

Figure 2: List of IP links available

Note: If you have multiple ethernet ports and have already set up a bond, follow this guide: https://blog.alexis.lc/docker-macvlan-network-synology

We will link our macvlan to this physical port so that information and be routed from outside the NAS to the docker container.

Docker and MACVLANs

Warning! This is the danger zone. If you mess up and/or want to get your network settings back to normal follow these steps. TL;DR: find and press the reset button on the back of your NAS for 4 seconds until you hear a beep, then release.

Now that we have our address range reserved and we know which device we can link our macvlan to, it is time to create our docker network and a macvlan network!

Step 1: Create the necessary docker network:

 docker network create -d macvlan \
  -o parent=eth0 \
  --subnet=192.168.2.0/24 \
 	--gateway=192.168.2.1 \
  --ip-range 192.168.2.200/27 \
 	--aux-address="host=192.168.2.201" \
   dockervlan

--aux-address reserves the address from our subnet (this is the new ip my NAS host will be accessed from on the macvlan network)

--ip-range is the range of IPs that can be assigned by docker

--gateway the gateway docker will use to communicate with the world (this is my router address)

--subnet the macvlan's subnet we will be creating

-o parent specifies the interface through which we want to comminicate

Synology NAS MACVLAN

The next step is to create a MACVLAN that will act as a new host and network and provide new IP addresses to the containers we attach to it.

First create a MACVLAN and add a fictitious MAC address to it. This is so that if you need to start over, you don't have multiple virtual nodes popping up in your router

sudo ip link add link eth0 name macvlan0 address 02:42:C0:A8:02:C9 type macvlan mode bridge

Then assign the reserved host address (aux-address from above) to the MACVLAN

sudo ip addr add 192.168.2.201/32 dev macvlan0

Spin up the MACVLAN

sudo ip link set macvlan0 up

Allow routing to the subnet

sudo ip route add 192.168.2.200/29 dev macvlan0

Now you should see a new host on your network with ip 192.168.2.201 and MAC address 02:42:C0:A8:02:C9

Make sure the synology can get packets to the macvlan subnet

sudo iptables -A INPUT -s 192.168.2.200/29 -j ACCEPT &&
sudo iptables -A OUTPUT -d 192.168.2.200/29 -j ACCEPT &&
sudo iptables -A FORWARD -s 192.168.2.200/29 -j ACCEPT &&
sudo iptables -A FORWARD -d 192.168.2.200/29 -j ACCEPT

Traefik with a new IP

To assign Traefik it's own IP so that the NAS does not interfere with traefik (by taking up ports 80 and 443) add the following to your docker compose:

service: . . networks: default: #eth0 linked network traefik-net: #traefik's network proxy: #proxy network mac_address: "02:42:C0:A8:02:C9" . . . #define networks networks: traefik-net: external: true proxy: external: true default: external: name: "dockervlan"

Note the 3 networks:

default/dockervlan this docker network is the subnet that exists in the router and is linked to eth0. This manages all external communication

proxy socket-proxy docker network (never to be exposed)

traefik-net the network any container will use in order to communicate with traefik

Sources:

https://blog.oddbit.com/post/2018-03-12-using-docker-macvlan-networks/

https://community.synology.com/enu/forum/1/post/133969?page=2&sort=oldest

https://www.reddit.com/r/synology/comments/s5j9d8/howto_vlan_configuration_with_docker/

"Only" having an authenticator doesn't stop malicious containers from reaching outside. Least privileges and network segmentation is the minimum necessary.