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  • Page 1 – Main Setup
    1. Install Docker, Enable SSH & SNMP
    2. SSH into Syno NAS
    3. MariaDB Setup
    4. LibreNMS Setup
    5. Configure LibreNMS
    6. Add your Synology & Other Devices

After Setup / Optional(s)

Change the default admin password

Under Gear Settings Icon (Top right, left of Global Search) > Manage Users

Edit the current admin user and change its default password


Back to the Terminal, we can set up custom settings to LibreNMS to exclude features like Billing and Services etc since we are not using them

cd /volume1/docker/librenms
vi custom.config.php

Google on how to use “vi” as Synology does not have “nano”

Paste in the following example, which is heavily customised for Synology devices, change accordingly to LibreNMS’s documentation


$config['show_locations'] = 1; # Enable Locations on menu
$config['show_locations_dropdown'] = 1; # Enable Locations dropdown on menu
$config['show_services'] = 0; # Enable Services on menu
$config['int_customers'] = 0; # Enable Customer Port Parsing
$config['summary_errors'] = 1; # Show Errored ports in summary boxes on the dashboard
$config['int_transit'] = 0; # Enable Transit Types
$config['int_peering'] = 0; # Enable Peering Types
$config['int_core'] = 0; # Enable Core Port Types
$config['int_l2tp'] = 0; # Enable L2TP Port Types
$config['force_ip_to_sysname'] = true;
$config['enable_bgp'] = 0; # Enable BGP session collection and display
$config['enable_syslog'] = 0; # Enable Syslog
$config['enable_inventory'] = 0; # Enable Inventory
$config['enable_pseudowires'] = 0; # Enable Pseudowires
$config['enable_vrfs'] = 0; # Enable VRFs
$config['enable_sla'] = 0; # Enable Cisco SLA collection and display
$config['bad_if_regexp'][] = '/^lo.*/'; // ignore loopback interface
$config['bad_if_regexp'][] = '/^docker[w]+$/'; // ignore docker interfaces
$config['ignore_mount_regexp'][] = "/^/volume1/@docker/.*/"; // Syno-NAS ignore docker mounts
$config['ignore_mount'][] = "/dev/shm"; // Syno-NAS
$config['ignore_mount_regexp'][] = "//run.*/"; // Syno-NAS
$config['ignore_mount'][] = "/sys/fs/cgroup"; // Syno-NAS
$config['ignore_mount'][] = "/tmp"; // Syno-NAS

After you have edited the custom.config.php to your liking, remember to perform a restart on your docker container to reflect the new settings

docker restart librenms


As alerting will be out of the scope of this tutorial, I’m sure you can explore around and tinker with the settings. Email alerts will be sent out via SMTP with regards to using jarischaefer/docker-librenms’s container

Just to list a few alert transports (or methods if you wish in the tech world) in LibreNMS if you wish to use other transports other than email:

  • Pushover
  • Discord (free)

Discord Notifications

Alerts can be useful as they will notify you when something goes down and sends you a recovery message with elapsed downtime

Please do keep this in mind, if you are planning to monitor devices that often have downtime, it will make sense to have the LibreNMS installed on a location that is 24hours online with a stable Internet connection. If your LibreNMS server or Network goes down, how will it be able to send an alert to you?

My scenario with LibreNMS is that I have two LibreNMS instances installed at two different physical locations

One of the locations suffers from electrical power blackouts and unstable Internet connection, while the other location is located in a city with 24hrs electricity and no Internet downtime

The stable LibreNMS is used to monitor the Router of the unstable location and sends alerts when necessary

While not everyone has access to two or more physical locations, your only choice would be to set up a hosted server Eg: DigitalOcean

Use SVG graphs

LibreNMS can output SVG graphs which has better clarity than png

Settings (Gear icon beside Search bar) >> Global Settings >> Webui Settings >> Graph settings >> graph type


I have run the above commands multiple times previously when I was still testing LibreNMS and configuration, so this should work as intended on a Synology NAS

If you come across any errors, it does not hurt to remove the Docker container, check the docker run command and run it again as it can be confusing with many docker variables

Some quick helpful docker commands

List all containers / Or view them in your DSM Docker app

  • docker ps -a

Check your current Docker gateway (your NAS IP when access from inside Docker)

  • docker inspect bridge

Start container from terminal

  • docker start container-name

Stop container from terminal

  • docker stop container-name

Remove container from terminal

  • docker rm container-name

Start a docker bash from terminal

  • docker exec -it container-name bash

If you decide to remove any of the MariaDB or LibreNMS containers, remember to also remove the existing data from the persistent data folder eg: /volume1/docker/mariadb , /volume1/docker/librenms

  • rm -r foldername/

Be careful when running rm -r with root privileges, ensure you are deleting correct folders.
Eg: rm -r /volume1/ will delete your whole volume1 folder!!! Always make sure you are in the correct folder while running commands. If in doubt, go back to DSM >> File Station and delete folders/files the GUI way

  • # List files in directory
  • rm -r mariadb/
  • rm -r librenms/
Stop, Remove, Delete Containers

Stop, Remove, Delete Containers

Networking issues & a quick 101

From your Syno terminal, ensure your Syno NAS can communicate with other devices (eg: ping). If your NAS is able to communicate with the devices, there are usually no problems with your docker commands as the docker network interface is bridged to your NAS. This usually boils down to device firewall that is blocking UDP port 161

Check Firewalls on Synology and Device(s)

Check your Synology & device firewalls, static routes, router settings etc to allow UDP port 161 SNMP protocol, especially true for remote polling of devices


Router level Site-to-Site VPN users, most of the case the routes are automatically added for you by your Router. If you are using a 3rd party VPN connection on your Syno, please add the relevant static routing for more advanced networks (eg: multiple local subnets)

If you suspect your container is having problems, you can troubleshoot further by running a docker bash terminal (docker exec -it librenms bash), and try to ping your devices and/or perform a snmpwalk

Troubleshooting steps

Aug 24, 2018 Update

  1. Open a LibreNMS container bash
    1. via Synology GUI
    2. via Portainer GUI >> Console
    3. Manually
    4. docker exec -it librenms bash
  2. Ping the device you wish to poll from the container bash
  1. ping
  2. librenms bash troubleshoot ping

    librenms bash troubleshoot ping

  3. If ping is successful, means your Synology and device is able to “talk” with each other. A big part of your network issue has been fixed. Usual cases are when Device A sends out to Device B (received), but Device B doesn’t reply due to Firewall and/or OS restrictions.
    If you are unable to ping your device, you will need to check your Synology, router & device firewalls. Some device firewall by default will block ICMP ping
  • Anyhow, proceed to the next step to test your SNMP udp port 161
      1. Ensure device SNMP is enabled, check community passphrase, check which snmp protocol, v1, v2c, v3 is in use, and perform a snmpwalk on it
        Eg: using v2c
      2. snmpwalk -v 2c -c your-community-passphrase
    1. librenms bash troubleshoot snmpwalk

      librenms bash troubleshoot snmpwalk

    2. If it is successful, you will see a bunch of numbers
    3. If it is unsuccessful, you will see a timeout
      1. Check device snmpd configuration eg: /etc/snmp/snmpd.conf or Windows’s snmpd service and ensure it is allowing connections from certain IPs or set to allow all
      2. Check device firewall configuration is accepting/allowing port udp 161
      3. Enable and Restart snmpd service
      4. Restart device

Synology & Docker Network 101

Context: Default Synology docker networking settings

LibreNMS Docker Behind Synology Network Topology

LibreNMS Docker Behind Synology Network Topology

local-syno-subnet eg:

syno communicate with other devices


docker subnet

Communicating between docker containers can be done via their IPs or “–link” (which is depreciated in docker but is easier to setup and understand in this tutorial)

syno-docker: (bridge gateway)
external-ip(your syno ip):
container1: exposed-port: 1234 internal-port: 88 (eg: -p 1234:88)
container2: exposed-port: 4567 internal-port: 99 (eg: -p 4567:99)

Devices subnet to communicate with docker containers

device to container1 in syno: >>
device to container2 in syno: >>

note that you are still using syno’s ip address instead of the subnet

In layman’s terms, the docker network is running inside your Syno NAS, which only your NAS can “see”. External devices do not know that the docker network exists

When external devices contact the relevant ports on your Syno NAS (1234, 4567), it will forward to the respective docker container IP and ports (88, 99)

Updating Containers

To update containers, there are three methods:


  1. Go to your Docker GUI in DSM
  2. Under the “Registry” tab, search for your image (in this case, jarischaefer)
  3. Click on “Download” and choose your tag (eg: latest)
  4. Wait for the download to complete, a notification will appear in your DSM
  5. Under “Container” tab, stop your current running LibreNMS container. (Right-click or click on the switch)
  6. Right-click on Container >> Action >> Clear
  7. Start LibreNMS container again
  8. The container will be updated with the newly downloaded image with previous “docker run” settings

Portainer  is a great lightweight docker management UI. There’s nothing against Synology’s own GUI docker management environment (sluggish at times…), but I prefer Portainer’s environment as it has more details.

Portainer also has the ability to open a bash console in your containers, all from the web UI!

When you explore through the different sections, you will find that you have many unused images created when you were testing with containers. You can use Portainer to remove the unused images and free some disk space. Moreover, when you see such details, you start to understand more about how Docker works

  1. Install portainer in docker
    • Create the necessary portainer folder in your docker directory eg: /volume1/docker/portainer
    • docker run -d -p 9000:9000 -v /var/run/docker.sock:/var/run/docker.sock -v /volume1/docker/portainer:/data --name portainer portainer/portainer
  2. Login and setup admin user during first install, choose local environment eg: /var/run/docker.sock
  3. Go to the “Containers” section, choose the container you wish to update eg: librenms , and click on “Recreate”


  4. A popup will appear with an option to pull the latest image during recreation

    Ensure “Pull latest image” is on

Note: If your container/image is not being updated, please make sure your container’s image is using the “latest” tag. Eg: jarischaefer/docker-librenms:latest

Reduce/Minimum downtime during an upgrade

Aug 24, 2018 Update

If you were to “Recreate” via Portainer’s GUI, you will experience longer downtime as Portainer will stop the container, and then pull the image. This is not ideal if the image is large or your WAN is not fast enough

To minimise downtime, you can pull the image in advance, and then proceed to “Recreate” via the GUI with the “Pull latest image” switch turned on. This step will be similar to the Manual steps below. This way, your only downtime is the restart of the container

  1. Navigate to “Images” section, choose your LibreNMS container ID
    portainer - librenms image list

    portainer – librenms image list

  2. Ensure the tag you wish to update to and proceed to pull the image
    portainer pull image first

    portainer pull image first

  3. Wait for the pull to complete, and proceed to “Recreate” the image as described previously 😉


Jun 23, 2018 Update – Highly recommend using Portainer management UI as above. Copying/Pasting commands can be a hassle if you run more than 5 containers.

Remember those docker run commands I told you to save earlier?

Applicable to Synology users and other systems (eg: Linux)

  1. SSH into your device
  2. Update the image
    • docker pull jarischaefer/docker-librenms:latest
  3. Stop and remove the current running container
    • docker stop librenms
      docker rm librenms
  4. Paste your previous docker run commands
    • docker run ... ...

After Care & Upgrade

If you encounter problems like this after an upgrade eg: from earlier than v1.43 to newer than 1.43, or in general

LibreNMS Error

LibreNMS Error

Instructions from jarischaefer/docker-librenms

Validate LibreNMS

Validate LibreNMS

Get to LibreNMS’s container bash from Synology Console/Terminal

docker exec -it librenms bash

and run the following to validate your setup

source /etc/librenms_environment
cd /opt/librenms
php validate.php
Validate Results

Validate Results

And then follow, copy/paste LibreNMS’s instructions to fix the problems, which are usually permission errors since we are running LibreNMS in a docker container, which complicates matters but safe to leave it. (Syno has no setfcl)

Continue to Page 3

  • Page 3
    1. Afterword
    2. Archive