isle/docs/operator/firewalls.md

Configuring Firewalls

When providing resources on your host, whether network or storage, you will need to ensure that your host's firewall is configured correctly to do so.

To make matters even more confusing, there are actually two firewalls at play: the host's firewall, and Isle's own VPN firewall.

Your host's firewall filters all traffic across all network interfaces, while Isle's VPN firewall filters traffic only across the network interfaces it creates itself. This means there is some duplication of responsibility across the two, and so configuring both is required for providing resources.

isle does not automatically configure your host's firewall to any extent!

Configuring the Host Firewall

By default Isle's VPN firewall will reject all inbound traffic on VPN interfaces. This is a safe default, and so for simplicity it is recommended to configure the host firewall to allow all traffic on Isle networks. To do this on Linux using iptables, for example, you would add something like this to your iptables configuration:

-A INPUT --source <network CIDR> --jump ACCEPT

being sure to replace the network CIDR with the one for your network.

If you don't feel comfortable allowing Isle to deal with all packet filtering, you will need to manually determine and add the ports for each service to your host's firewall. You will need to manually specify any configured storage allocation ports if this is the approach you take.

Configuring the VPN Firewall

See the Configuring Networks document for notes on how to configure Isle networks. This guide assumes configuration using the CLI.

Isle uses the nebula project to provide its VPN layer. Nebula ships with its own builtin firewall, which only applies to connections coming in over the VPN interfaces which it creates for Isle. This firewall can be manually configured using the isle vpn firewall set of sub-commands, or using the configuration file.

The isle vpn firewall sub-commands are used to configure the VPN's firewall. Without any flags the isle vpn firewall show command will display the currently active firewall.

Isle will automatically open inbound ports on its firewall for services it provides, for example those necessary for storage allocations. When viewing open ports using isle vpn firewall show these automatically opened ports will appear separately under the internal_inbound section and are not configurable by the user.

isle vpn firewall show
# outbound:
#     - index: 0
#       port: any
#       proto: any
#       host: any
# inbound:
#     - index: 0
#       port: any
#       proto: icmp
#       host: any
#     - index: 1
#       port: "22"
#       proto: tcp
#       host: my-laptop
# internal_inbound:
#     - port: "3901"
#       proto: tcp
#       host: any
#     - port: "3900"
#       proto: tcp
#       host: any

When making changes to the firewall, all changes are first applied to a staging version of the firewall. The staged version can be viewed by adding the --staged flag to the show sub-command.

isle vpn firewall remove --from inbound --indexes 1

isle vpn firewall show --staged
# outbound:
#     - index: 0
#       port: any
#       proto: any
#       host: any
# inbound:
#     - index: 0
#       port: any
#       proto: icmp
#       host: any

isle vpn firewall add --to inbound --port 53 --proto udp --host any

isle vpn firewall show --staged
# outbound:
#     - index: 0
#       port: any
#       proto: any
#       host: any
# inbound:
#     - index: 0
#       port: any
#       proto: icmp
#       host: any
#     - index: 1
#       port: "53"
#       proto: udp
#       host: any

Once the staged firewall is in the desired state, it can be applied using the commit sub-command.

isle vpn firewall commit

If you wish to instead discard all staged changes you can use the reset sub-commmand.

isle vpn firewall reset