• Configuring Cloudflare to secure your Nable instance
  • Known Issues
  • 1. Aquire a domain name, Cloudflare Account and configure Cloudflare's nameservers (NS)
  • 2. Configure NAT rules.
  • 3. SSL/TLS
  • 4. Firewall
  • 5. Access
    • Login Methods
    • Access Policies
      • Main Policy
      • Access Groups
      • Access Policies - Bypass
  • Network
  • Final Step
  • Testing
    • Authentication
    • Agents
    • Finalizing and Potential Issues
      • Agents
      • Monitoring for Issues
      • Break Glass Scenario

Configuring Cloudflare to secure your Nable instance

Credit:

All credit to get this working in the first place goes to the work done by /u/Hefty-Hovercraft: https://www.reddit.com/r/msp/comments/g3iwig/how_we_used_a_free_cloudflare_plan_to_hide_our/

Also tweaks, improvements, and 2021.1+ support credit goes to:

• /u/square-mulberry8261
• /u/m9832
• /u/likwid9
• various members of the https://n-central-community.slack.com/ team

Note: This is confirmed working on self-hosted instances only at this time. This guide will focus on 2021.1 HF5, but should work on previous builds if the version specific steps in this guide are configured correctly.

This is using the free tier from Cloudflare - there is no cost to implement this. There are benefits of going with a paid plan, including additional traffic insight, CNAME redirect, WAF, etc., but this guide will not touch on those features.

This guide will utilize a new domain (hereinafter referred to as "CF Domain") that will be where you point agents and WebUI users. It is possible to keep your existing domain/subdomain name and utilize Cloudflare with a CNAME redirect, but that specific setup will not be covered here.

Known Issues

• 2021.1+: This build added a new "Ecosystem Agent", which uses gRPC to communicate and is currently not working properly with Cloudflare. If you use any of the Nable Integrations like Intune or EDR and are on Nable build 2021.1, you will experience issues and should take that into consideration.

1. Aquire a domain name, Cloudflare Account and configure Cloudflare's nameservers (NS)

If you don't already have a Cloudflare account, go to https://dash.cloudflare.com/sign-up and sign up for a free account. Be sure to configure MFA on the account.

Update the nameservers for your domain to use the provided Cloudflare nameservers:

• See https://support.cloudflare.com/hc/en-us/articles/205195708-Changing-your-domain-nameservers-to-Cloudflare

Once your domain has been updated with Cloudflare's nameservers, log into your Cloudflare admin portal at https://dash.cloudflare.com/ and go to the DNS tab. Configure an A record to point to your Nable server IP. If possible, use a different IP that your existing Nable hostname resolves to.

You should see something similar to this:

2. Configure NAT rules.

If you used a new IP for your CF Domain, open port 80 and 443 to your Nable server. Allow ONLY Cloudflare IPs to connect via this IP. https://www.cloudflare.com/ips/

Skip this step for now if you will be using your existing IP.

3. SSL/TLS

In the Cloudflare admin portal, under SSL/TLS -> Overview, be sure encryption mode is set to Full

Under SSL/TLS -> Edge Certificate:

• Enable Always Use HTTPS
• Set Minimum TLS Version to 1.2
• Enable TLS 1.3
• Enable Automatic HTTPS Rewrites

4. Firewall

Go to Firewall -> Firewall Rules

• Rule 1:
  • Name: Block Known Bots
  • When incoming requests match… "Known Bots" equals "On"
  • Then: Block
  • 
• Rule 2:
  • Name: Block Country
  • When incoming requests match… "Country" does not equal countries you operate in
  • Then: Block
  • 
• Rule 3:
  • Name: Agent & Probe Traffic to NC
  • When: Use edit expression and paste the following: (http.request.uri.path eq "/dms2/services2/ServerMMS2" and http.user_agent eq "Agent-Probe" and http.request.method eq "POST") or (http.request.uri.path eq "/bosh/bosh/" and http.user_agent eq "" and http.request.method eq "POST") or (http.request.uri.path eq "/dms2/services2/ServerEI2" and http.user_agent eq "Mozilla/5.0 (compatible)" and http.request.method eq "POST") or (http.request.uri.path contains "/images/agent/" and http.user_agent eq "") or (http.request.uri.path contains "agentAssetImageMap.txt") or (http.request.uri.path contains "/download/") or (http.request.uri.path eq "/dms2/services2/ServerII2" and http.user_agent eq "Mozilla/5.0 (compatible)" and http.request.method eq "POST") or (http.request.uri.path eq "/FileTransfer/") or (http.request.uri.path eq "/commandprompt/") or (http.request.uri.path contains "/LogRetrieval") or (http.request.uri.path eq "/dms2/services2/ServerMMS2" and http.user_agent eq "gSOAP/2.8" and http.request.method eq "POST") or (http.request.uri.path eq "/dms2/services2/ServerEI2" and http.user_agent contains "MSP%20Anywhere%20Daemon (unknown version)" and http.request.method eq "POST") or (http.request.uri.path eq "/dms2/services2/ServerII2" and http.user_agent contains "MSP%20Anywhere%20Daemon (unknown version)" and http.request.method eq "POST") or (http.request.uri.path eq "/dms2/services2/ServerII2" and http.user_agent eq "CodeGear SOAP 1.3" and http.request.method eq "POST") or (http.request.uri.path eq "/dms2/services2/ServerII2" and http.user_agent eq "Mozilla/4.0 (compatible; MSIE 6.0; MS Web Services Client Protocol 4.0.30319.42000)" and http.request.method eq "POST") or (http.request.uri.path eq "/dms2/hello") or (http.request.uri.path eq "/dms2/services2/ServerII2" and http.user_agent contains "Take%20Control%20Viewer%20for%20N-central/1 CFNetwork/" and http.request.method eq "POST") or (http.request.uri.path eq "/dms2/services2/ServerMMS2" and http.user_agent contains "Mozilla/4.0 (compatible; MSIE 6.0; MS Web Services Client Protocol" and http.request.method eq "POST")
  • Then: Allow
• Rule 4:
  • Name: WebUI
  • When: Use edit expression and paste the following. Be sure to replace YOURSONAMEHERE with your Nable SO Name: (http.request.uri.path eq "/") or (http.request.uri.path contains "/login/") or (http.request.uri.path contains "/dojoroot/") or (http.request.uri.path contains "/favicon.ico") or (http.request.uri.path contains "/cdn-cgi/access/authorized") or (http.request.uri.path contains "/images/") or (http.request.uri.path contains "/stylesheets/") or (http.request.uri.path contains "/js/") or (http.request.uri.path contains "/angular/") or (http.request.uri.path contains "/fonts/") or (http.request.uri.path contains "/rest/") or (http.request.uri.path eq "/assetDiscoveryEditDeviceAction1.do") or (http.request.uri.path eq "/dms/services/ServerUI") or (http.request.uri.path eq "/dms2/services2/ServerUI2") or (http.request.uri.path eq "/UIFileTransfer") or (http.request.uri.path contains "/missingPatchesReportAction.do") or (http.request.uri.path eq "/so/YOURSONAMEHERE") or (http.request.uri.path eq "/detailedAssetAction.do") or (http.request.uri.path eq "/deepLinkAction.do") or (http.request.uri.path contains "/downloadFileServlet.download") or (http.request.uri.path contains "/configurationSummaryAction.do") or (http.request.uri.path contains "/IndexAction.action") or (http.request.uri.path contains ".action") or (http.request.uri.path contains "/reportAction.do") or (http.request.uri.path contains "/chartRendererAction.do") or (http.request.uri.path contains "/patchInventoryReportAction.do") or (http.request.uri.path contains "/dms/") or (http.request.uri.path eq "/dms2/services2/ServerII2" and http.user_agent contains "Mozilla/4.0 (compatible; MSIE 6.0; MS Web Services Client Protocol" and http.request.method eq "POST") or (http.request.method eq "GET" and http.request.uri.path eq "/login") or (http.request.uri.path eq "/dms2/hello") or (http.request.uri.path contains "/webstart") or (http.request.uri.path eq "/dms2/services2/ServerII2" and http.user_agent eq "Embarcadero SOAP 1.4" and http.request.method eq "POST")
  • Then Allow
• Rule 5:
  • Name: Block everything else
  • When incoming requests match… "URI" does not contain "randomfailstring"
  • Then: Block
  • 

5. Access

Login Methods

Navigate to the Access tab in the Cloudflare admin page. By default you should have One-Time Pin as an option for Login Methods, but you should add an Identity provider like Azure AD or another SAML compatible IdP. This will be used to allow your internal team/techs to authenticate with Cloudflare and access your Nable server login page. This guide will not go into depth on configuring a IdP, pleae see https://developers.cloudflare.com/access/about/quick-start for additional information.

If you require users outside your IdP be able to access Nable (ie Clients who access their machines), you can configure a public IdP like Facebook, or create an Access Group and utilize the One-Time Pin function. We will touch on this later.

Access Policies

First, create your access policies to let your users access the WebUI.

Main Policy

For Nable 2020.1 and OLDER:

• Name: Main Policy
  • Leave the application domain subdomain and path values blank
  • Click ‘Add New Policy’, name it ‘Technicians’ and set to Allow
  • Include ‘Emails Ending in’ @ yourmsp.com (whatever your IdP email suffix is)
  • Configure Session Duration to be 12 hours
  • Save and close the Access Policy

For Nable 2021.1 and NEWER:

• Main Policy
  • Name: Leave the application domain subdomain blank, and enter login for the path
  • Click ‘Add New Policy’, name it ‘Technicians’ and set to Allow
  • Include ‘Emails Ending in’ @ yourmsp.com (whatever your IdP email suffix is)
  • Configure Session Duration to be 12 hours
  • Save and close the Access Policy

Access Groups

For both versions of Nable, if you would like to allow specific external email addresses to be able to login sing One-Time PINs:

• Create an Access Group called "Client Access - Nable" or similar
• Include: Emails
  • Enter the email addresses you would like to allow into the group
• Go back to your Main Policy, and in addition to your existing "Technicians" policy, add a new policy called "Client Access - Nable" or similar.
  • Set this Policy to Allow
  • Include the Access Group you just created

This is an example Main Policy for a 2021.1 that is configured to allow both IdP users and an Access Group to access the Nable WebUI:

Access Policies - Bypass

For both versions of Nable, create additional Accesss Policies for each of the following, entering each as the path of the policy. The policy should be configured for Bypass for Everyone on each.

• /bosh/bosh/
• /commandprompt/
• /dms/
• /dms/services/ServerMMS/
• /dms/services/ServerUI
• /dms2/hello
• /dms2/services2/ServerEI2/
• /dms2/services2/ServerII2/
• /dms2/services2/ServerMMS2/
• /dms2/services2/ServerUI2
• /download/
• /FileTransfer/
• /fonts/
• /images
• /images/agent/
• /indexIntegrationExternalPageAction.action
• /LogRetrieval/
• /rest/dashboard
• /rest/device-active-incident/
• /rest/lan-devices
• /services/ServerMMS/
• /tunnel/request.tunnel
• /UIFileTransfer

Here is an example of one of the above paths configured in it's policy:

For Nable 2021.1 and NEWER Only:

This step is optional, but no loss of functionality has been discovered yet.

Nable 2021.1+ brought a new built-in Envoy proxy to the Nable server, which redirects to /login automatically when accessing the site. Unfortunately for our use, this also leaves our root CF Domain accessible to scraping, and able to be easily identified as an Nable server. We can reduce our exposure by enabling a redirect on the page:

• Create a bypass policy for the root of your Application Domain (subdomain and path both blank):
  • 
• Navigate to Rules, and create a new Page Rule to redirect the root of your new CF Domain to /login:
  • 

Network

Ensure WebSockets is enabled under the Network tab (this appears to be the default).

Final Step

For Nable 2021.1 and NEWER, we need to disable a security setting that will cause issues (sessions resetting, etc.).

• In your Nable server, Navigate to the System Level (Red).
• Go to Administration -> Mail and Network Settings -> Network Security
• Change the "HANDLING IP-BASED UI LOGIN ATTACKS" setting to "Off"

Testing

At this point we are now ready to test.

Authentication

Navigate to your CF Domain, you should be prompted with the Cloudflare authentication page:

Ensure your IdP authentication works correctly. You should be brought directly to your Nable server login screen after authenticating.

Agents

To start testing agent connectivity, go to or create a test/demo Customer in your Nable:

• Go to Administration -> Defaults -> Agent and Probe Settings
• Add your new CF Domain to the top of the Server Address fields, check the box to propagate
• Ensure you port number is 443, check propagate if you change this
• Change BOSH traffic to Only send BOSH traffic over port 443 and check the box to propagate
• Click Save

You should see traffic start to appear in your Cloudflare Firewall Rules:

Important: It is possible for traffic to appear in the Firewall Rules while the agent is still actually communicating with the old Nable server address. Even if you remove the old server address from the Agent and Probe Settings, the agents appear cache the old name if they have communication issues with the new server address. A few options to confirm traffic is going completely through Cloudflare:

• Block traffic to your old Nable hostname/IP on the agent end
• Block the IP the agent is connecting from at your server end
• Check the file C:\Program Files (x86)\N-able Technologies\Windows Agent\config\ServerConfig.xml on an agent you updated. The <ServerIP> key should be your new server address.
  • Here is a simple PS Script that can output with an AMP to monitor your agents:

[xml]$xmlInput= Get-Content -Path "C:\Program Files (x86)\N-able Technologies\Windows Agent\config\ServerConfig.xml"
$ServerIP = $xmlInput.ServerConfig.ServerIP
$BackupServerIP = $xmlInput.ServerConfig.BackupServerIP

Finalizing and Potential Issues

Agents

Once you have confirmed your test agents are communicating with Nable via Cloudflare successfully, you can start rolling out the new Agent/Probe Communication settings to additional Customers. Keep in mind you will eventually need to lock down/disable your old Nable server IP (if you are using a new IP) or lock down your existing IP to only Cloudflare IPs (if your CF Domain and your old Nable server address share the same IP). Once you do this, any offline device that has not pulled down the new config will be dead in the water so to speak.

One option to avoid this would be to add your new CF Domain as a backup server address NOW, once you have confirmed basic functionality and before you have committed to migrating every agent over to the CF Domain. Then work with your clients to get any offline or spare machines checking ASAP. As long as the CF Domain is somewhere in that Server Address list, it should be able to check in when it gets powered on again.

Another option would be to keep your client offices WAN IPs whitelisted on your Nable IP NAT rules for a few weeks/months, to allow on-site devices to always check in and pull down the new Agent Communication settings.

Monitoring for Issues

Once you have some traffic flowing through Cloudflare, it is very important to check for any legitimate WebUI or Agent traffic getting blocked. This guide has been created largly using trial and error, so it is possible additional changes need to be made. If you find something needs to be added, please share!

Break Glass Scenario

It would be wise to keep your old Nable hostname configured as a backup Server Address in your Agent/Probe Communication settings. In the event Cloudflare had an outage, or this configuration stopped working you could point that hostname to your Nable server IP. You would need to allow all IPs to connect (not just Cloudflare's) but your agents would be able to check back in.