mikaela.github.io/n/firewalld.md

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# Quick note on firewalld usage
This is practically [/ufw](/ufw), but fore Firewalld which Fedora comes with.
The blog post also predates me having a /n directory here.
**_After done, run `sudo firewall-cmd --reload`_**
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- [Zones](#zones)
- [Protocols](#protocols)
- [Services](#services)
- [Ports](#ports)
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## Zones
firewalld zones are privilege of NetworkManager users, this tends to be
a systemd-networkd household. Then again I don't believe in absolutely trusted
zones.
Zone would be specified by `--zone=home` in the commands. The other zone I
could imagine using is `public`.
## Protocols
```bash
sudo firewall-cmd --add-protocol=ipv6-icmp --permanent
```
- Tells computers when things go wrong with IPv6 network. See also [Neil Alexander: Understanding ICMP and why you shouldn't just block it outright](https://neilalexander.dev/2017/04/16/understanding-icmp).
- _Motivation for being here is [20/20 in IPv6-test.com](https://ipv6-test.com)._
## Services
```bash
sudo firewall-cmd --add-service=ssh --permanent
sudo firewall-cmd --add-service=mosh --permanent
sudo firewall-cmd --add-service=ntp --permanent
sudo firewall-cmd --add-service=syncthing --permanent
sudo firewall-cmd --add-service=mdns --permanent
```
- I trust Chrony (ntp) to not allow it to be used from outside of LAN
as `firewalld` is apparently not designed with limiting source
addresses in mind.
- `syncthing` is the client, not to be confused with `syncthing-gui`
or `syncthing-relay`.
## Ports
```bash
sudo firewall-cmd --permanent --add-port=9001/udp
sudo firewall-cmd --permanent --add-port=6771/udp
```
- `9001/udp` is Yggdrasil automatic peering, although link-local and
unlikely to be recognised by predefined rules.
- `6771/udp` is [Bittorrent Local Peer Discovery](http://bittorrent.org/beps/bep_0014.html)