# Configuring Firewalls

When providing resources on your host, whether
[network](./contributing-a-public-address.md) or
[storage](./contributing-storage.md), 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 the VPN firewall.

## Host Firewall

The host you are running isle on will almost definitely have a firewall
running, separate from the VPN firewall. If you wish to provide services for
your Isle network from your host, you will need to allow their ports in your
host's firewall.

**isle does _not_ automatically configure your host's firewall to any extent!**

One option is to open your host to all traffic from your Isle network, and
allow the VPN firewall to be fully responsible for filtering traffic. 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.

## VPN Firewall

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

Any storage allocations which are defined will have their network ports
automatically added to the VPN firewall by Isle. This means that you only need
to configure the VPN firewall if you are hosting services for your isle network
besides storage.

[nebula]: https://github.com/slackhq/nebula
[nebulafirewall]: https://nebula.defined.net/docs/config/firewall
[configfile]: ./configuring-networks.md

### Configuring the VPN Firewall

See the [Configuring Networks](./configuring-networks.md) document for notes on
how to configure Isle networks. This guide assumes configuration using the CLI.

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.

```bash
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
```

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.

```bash
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.

```bash
isle vpn firewall commit
```

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

```bash
isle vpn firewall reset
```