Merge pull request #228 from 3hhh/anon

anonymize MAC & hostname: misc fixes
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Ivan 2022-11-12 15:02:43 +00:00 committed by GitHub
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@ -25,6 +25,7 @@ These steps should be done inside a template to be used to create a NetVM as it
Write the settings to a new file in the `/etc/NetworkManager/conf.d/` directory, such as `00-macrandomize.conf`. Write the settings to a new file in the `/etc/NetworkManager/conf.d/` directory, such as `00-macrandomize.conf`.
The following example enables Wi-Fi and Ethernet MAC address randomization while scanning (not connected), and uses a randomly generated but persistent MAC address for each individual Wi-Fi and Ethernet connection profile. The following example enables Wi-Fi and Ethernet MAC address randomization while scanning (not connected), and uses a randomly generated but persistent MAC address for each individual Wi-Fi and Ethernet connection profile.
It was inspired by the [official NetworkManager example](https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/blob/main/examples/nm-conf.d/30-anon.conf).
~~~ ~~~
[device] [device]
@ -34,12 +35,18 @@ wifi.scan-rand-mac-address=yes
wifi.cloned-mac-address=stable wifi.cloned-mac-address=stable
ethernet.cloned-mac-address=stable ethernet.cloned-mac-address=stable
connection.stable-id=${CONNECTION}/${BOOT} connection.stable-id=${CONNECTION}/${BOOT}
#use random IPv6 addresses per session / don't leak MAC via IPv6 (cf. RFC 4941):
#the below settings are optional (see the explanations below)
ipv6.addr-gen-mode=stable-privacy
ipv6.ip6-privacy=2 ipv6.ip6-privacy=2
ipv4.dhcp-client-id=stable
ipv6.dhcp-duid=stable-uuid
~~~ ~~~
* `stable` in combination with `${CONNECTION}/${BOOT}` generates a random address that persists until reboot. * `cloned-mac-address=stable` in combination with `connection.stable-id=${CONNECTION}/${BOOT}` generates a random MAC address that persists until reboot. You could use `connection.stable-id=random` instead, which generates a random MAC address each time a link goes up.
* `random` generates a random address each time a link goes up. * `ipv6.ip6-privacy=2` will cause a random IPv6 address to be used during every session. If you want to use an IPv6 address based on the already random MAC address, choose `ipv6.ip6-privacy=0`. Leaving this setting at the default is not recommended as it is basically undefined.
* `ipv6.addr-gen-mode=stable-privacy` is a default explicitly set by current versions of `NetworkManager` when creating new connection profiles. Setting it globally just makes sure that previously created connection profiles will use the same setting.
* `ipv4.dhcp-client-id=stable` and `ipv6.dhcp-duid=stable-uuid` instruct `NetworkManager` instruct `NetworkManager` to use a DHCP client identifier based upon the random MAC address. According to the current `NetworkManager` documentation the default is undefined. So it makes sense to set one explicitly.
To see all the available configuration options, refer to the man page: `man nm-settings` To see all the available configuration options, refer to the man page: `man nm-settings`
@ -53,17 +60,10 @@ You can check the MAC address currently in use by looking at the status pages of
DHCP requests _may_ also leak your hostname to your LAN. Since your hostname is usually `sys-net`, other network users can easily spot that you're using Qubes OS. DHCP requests _may_ also leak your hostname to your LAN. Since your hostname is usually `sys-net`, other network users can easily spot that you're using Qubes OS.
Unfortunately `NetworkManager` currently doesn't provide an option to disable that leak globally ([Network Manager bug 584](https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/issues/584)). However, the alternatives below exist. Unfortunately `NetworkManager` currently doesn't provide an option to disable that leak globally ([NetworkManager bug 584](https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/issues/584)).
### Prevent hostname sending However the `NetworkManager` versions as of Qubes OS 4.1 were found to not leak the hostname as long as the file `/etc/hostname` does **not** exist. This behaviour may be subject to change in future `NetworkManager` versions though.
So please always double check whether your hostname is leaked or not on e.g. your home router, via `wireshark` or `tcpdump`.
`NetworkManager` can be configured to use `dhclient` for DHCP requests. `dhclient` has options to prevent the hostname from being sent. To do that, add a file to your `sys-net` template (usually the Fedora or Debian base template) named e.g. `/etc/NetworkManager/conf.d/dhclient.conf` with the following content: If you want to decide per connection, `NetworkManager` provides an option to not send the hostname:
```
[main]
dhcp=dhclient
```
Afterwards edit `/etc/dhcp/dhclient.conf` and remove or comment out the line starting with `send host-name`. If the file does not exist, you may be fine already.
In any case it makes sense to double check your results on e.g. your home router, `wireshark` or `tcpdump`.
If you want to decide per connection, `NetworkManager` also provides an option to not send the hostname:
Edit the saved connection files at `/rw/config/NM-system-connections/*.nmconnection` and add the `dhcp-send-hostname=false` line to both the `[ipv4]` and the `[ipv6]` section. Edit the saved connection files at `/rw/config/NM-system-connections/*.nmconnection` and add the `dhcp-send-hostname=false` line to both the `[ipv4]` and the `[ipv6]` section.