User:John/FreedomBox/Network architecture

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Some notes about fbx network architecture. The goal is to make sure the user has secure access to their FreedomBox globally (on their LAN and from the Internet) before further network configuration continues (via plinth etc). This is the Out-Of-The-Box (OOTB) user experience that must happen before further access to FreedomBox services is provided.

Examples

In the use cases below the following configuration settings are used. Note that a table like this would be a good thing to ship on a physical card that comes with FreedomBox hardware. The user will need to know the value for some (not all) of these settings so they can configure their network services appropriately.

THINK: could we ship an "app" that helped users figure out some/all of these values?

THINK: which of these settings can we validate before applying?

Setting Value User needs to know?
User's internet router LAN IP 192.168.0.1 yes, but we can suggest
User's LAN subnet mask 255.255.255.0 yes, but we can suggest
User's LAN config web client IP 192.168.0.37 no
User's fbx LAN DHCP IP 192.168.0.123 not if freedombox.local MDNS works
User's fbx LAN static IP 192.168.0.2 yes
User's domain name example.com yes
User's FreedomBox name fbx.example.com we recommend 'fbx'
User's public IP address 139.218.130.78 yes, but we can offer to detect
User's internet DNS resolver 1.1.1.1 yes, but we can suggest

Use case

User wants to register their fbx on their existing domain name on their static home IP address

Note: these notes are just a bit of a brain dump at the moment. I will tidy them up to try and keep things manageable for the user.

Prerequisites:

  • user has a domain name registered (example.com)
  • user has DNS hosting and nameservers configured
  • user has access to do web based configuration of their DNS settings
    • note: in future we might be able to do for them via API from DNS hosting services
      • we could enumerate a list of supported providers (possibility for paid placement)

Out of scope:

  • no IPv6 configuration yet (we can add later)

Process:

  1. tell user to access http://freedombox.local/ (*not* https://freedombox.local/) after pluging in power and network then booting
  2. get the user to pick an IP address, subnet mask, and gateway for their fbx on their LAN
    • they will currently have a DHCP allocated address but as we can't ensure that IP will be constant/reserved (it's probably not) we want a static IP instead
  3. reconfigure fbx with nominated static IP address (192.168.0.2), netmask (255.255.255.0) and gateway (192.168.0.1)
    • don't release the DHCP address (192.168.0.123), the server will have two IP addresses during this process
  4. when static IP address settings are valid/successful (we could do a HTTP redirect dance to confirm):
    1. add firewall rule to block port 8080 access from all addresses other than current client IP address (192.168.0.37)
      • the rest of the configuration will need to be completed from the same client
      • this could be relaxed to blocking only gateway/router
    2. HTTP redirect over to the static IP address on port 8080 at e.g. http://192.168.0.2:8080/
  5. get the user to pick a DNS resolver service:
    • 1.1.1.1 and 1.0.0.1
    • 8.8.8.8 also an option
    • we could have a database of ISPs and their DNS servers
    • DNS resolver is another possibility for paid placement
    • could enter manually (and find in router config)
  6. ask the user to tell us thier domain name, e.g. 'example.com'
  7. ask user to pick a hostname at their domain, we recommend 'fbx'.
    • note that what we want is one single global unambiguous well-branded hostname for this fbx and something in the form 'fbx.example.com' is ideal
    • note that support for other domain aliases such as 'www.example.com' or 'blog.example.com' etc can be added later at the user's option
  8. tell the user to add an A record for 'fbx' for their public IP address.
    • we could offer to auto-detect public IP address
  9. configure our local Bind9 service:
    1. with DNS resolver nominated above (1.1.1.1)
    2. with a zone for 'fbx.example.com' and default A record of 192.168.0.2
      • a zone for the whole example.com could potentially be added later on, for now we just need fbx.example.com
  10. configure our Bind9 resolver on the router:
    1. tell user to configure router DNS proxy to point to 192.168.0.2
    2. tell user to configure broadband router DHCP server with DNS server 192.168.0.1 (that's probably current default)
    3. tell user to configure non-DHCP hosts with DNS server 192.169.0.1 (that's probably current default)
    4. tell user to add /etc/hosts (or equiv) for 192.168.0.2 fbx.example.com for any LAN hosts not using our Bind9 resolver (ideally there are no such hosts)
      • if hosts file is being used instead of DNS this might affect alias configurations if those are added later on, ideal the LAN DNS will be used in preference to hosts files
  11. tell user to configure router to point port 80 and port 443 at 192.168.0.2
    • ideally use "DMZ" configuration and just point all ports to 192.168.0.2
  12. THINK: do we want to offer to do port 80 probe to check router configuration?
  13. get a domain validated certificate from Let's Encrypt
    • public DNS should point to our home IP address
    • home IP address should NAT port 80 to our fbx
    • thus Let's Encrypt domain verification can complete
  14. configure Apache to use newly generated Let's Encrypt certificate
  15. HTTP redirect user to https://fbx.example.com/ and do the rest of the system configuration in plinth
    • we have successfully configured the FreedomBox to be accessible at https://fbx.example.com/ from both the user's LAN and from the public Internet
  16. now that we have secure comms between client browser and fbx server we can ask the user for the username/password for their account
    • might want to enforce this account config comes from the client browser (192.168.0.37)

User wants to register their fbx on a new domain name on their static home IP address

User wants to register their fbx on their existing domain name on their dynamic home IP address

User wants to register their fbx on a new domain name on their dynamic home IP address

Config

Email

We might use the default RDNS name as the hostname of our mail server and the hostname for our MX records.

fail2ban

If web services are behind a reverse proxy blocking IP addresses will be problematic, so maybe just don't do that? Needs some thought.

Processes

nmap discovery

Help user discover their fbx IPv4 address using an nmap command such as:

nmap -p 80 --open -sV 192.168.0.0/24

DHCP server status

Help user discover their fbx IPv4 address by reviewing the status of their DHCP server (often in the commodity internet router) and looking for 'freedombox' in the hostname or otherwise just trying allocated IP addresses to "see if they work".

Picking a DNS resolver

So we could go one of two ways when configuring our DNS resolvers:

  • fbx -> router -> internet
  • router -> fbx -> internet

The 'internet' resolvers could be one of:

  • user's ISP DNS servers
  • 1.1.1.1 and 1.0.0.1
  • 8.8.8.8
  • something else

Then we could either:

  1. make our fbx the DNS server on the LAN, which will defer to the router.
  2. make our router the DNS server on the LAN, which will defer to the fbx.

If we make the fbx the DNS server then we need to update the DHCP settings on the router to point the DNS server to our fbx.

If we make the router then DNS server then we need to update the DNS server settings on the router to point to our fbx.

Since it's six one way and half a dozen the other the way we will recommend is having the router be the primary LAN DNS server and the fbx as the DNS proxy to the internet. So that's router -> fbx -> internet. That means that we need to configure the DNS server on the router to be our fbx IP address (192.168.0.2 in our example). Because our fbx will defer to the actual DNS server we can offer choices (potentially paid placement) such as those listed as 'internet' DNS servers above (1.1.1.1).

HTTP redirect dance

Note: don't do this until you're reasonably certain your static IP address settings are valid. So that means check if an IP address is in use before configuring it as the static IP address.