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anonymize MAC & hostname / cleanups/updates
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docs/privacy/anonymizing-your-mac-address.md
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@ -3,26 +3,9 @@ Anonymizing your MAC Address
============================
Although it is not the only metadata broadcast by network hardware, changing the default [MAC Address](https://en.wikipedia.org/wiki/MAC_address) of your hardware could be [an important step in protecting privacy](https://tails.boum.org/contribute/design/MAC_address/#index1h1).
Currently, Qubes OS *does not* automatically "anonymize" or spoof the MAC Address, so unless this gets implemented by default you can randomize your MAC Address with the following guide.
## Upgrading and configuring Network Manager in Qubes
Newer versions of Network Manager have options for randomizing MAC addresses, and can handle the entire process across reboots, sleep/wake cycles and different connection states.
In particular, versions 1.4.2 and later should be well suited for Qubes. Qubes R4.0's default sys-net should have 1.8.2-4 by default.
However, use of the NetworkManager GUI to set these options is **unreliable** - there are numerous reports of changes not being saved for particular cards or interfaces.
You should check carefully that any settings you make in the GUI are saved, before relying on this method.
If the settings are not saved, you can use the method described below using a config file.
Network Manager 1.4.2 or later is available from the Fedora 25 repository as well as the Debian 10 repository.
Check that Network Manager version is now at least 1.4.2:
~~~
$ sudo NetworkManager -V
1.4.2
~~~
Qubes OS 4.1 and higher already anonymize all Wifi MAC addresses [by default](https://github.com/QubesOS/qubes-core-agent-linux/blob/master/network/nm-31-randomize-mac.conf) - they change during every Wifi session.
So there is **no need** to apply any of the below instructions if you're only interested in Wifi connections. Users requiring Ethernet MAC address anonymization may want to read on.
## Randomize a single connection
@ -68,7 +51,7 @@ You can check the MAC address currently in use by looking at the status pages of
## Anonymize your hostname
DHCP requests 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 ([Gnome Bug 768076](https://bugzilla.gnome.org/show_bug.cgi?id=768076)). However the below alternatives exist.
@ -79,48 +62,8 @@ Unfortunately `NetworkManager` currently doesn't provide an option to disable th
[main]
dhcp=dhclient
```
Afterwards edit `/etc/dhcp/dhclient.conf` and remove or comment out the line starting with `send host-name`.
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.
### Randomize the hostname
Alternatively you may use the following code to assign a random hostname to a VM during each of its startup. Please follow the instructions mentioned in the beginning to properly install it.
```.bash
#!/bin/bash
set -e -o pipefail
#
# Set a random hostname for a VM session.
#
# Instructions:
# 1. This file must be placed and made executable (owner: root) inside the template VM of your network VM such that it will be run before your hostname is sent over a network.
# In a Fedora template, use `/etc/NetworkManager/dispatcher.d/pre-up.d/00_hostname`.
# In a Debian template, use `/etc/network/if-pre-up.d/00_hostname`.
# 2. Execute `sudo touch /etc/hosts.lock` inside the template VM of your network VM.
# 3. Execute inside your network VM:
# `sudo bash -c 'mkdir -p /rw/config/protected-files.d/ && echo -e "/etc/hosts\n/etc/hostname" > /rw/config/protected-files.d/protect_hostname.txt'`
#NOTE: mv is atomic on most systems
if [ -f "/rw/config/protected-files.d/protect_hostname.txt" ] && rand="$RANDOM" && mv "/etc/hosts.lock" "/etc/hosts.lock.$rand" ; then
name="PC-$rand"
echo "$name" > /etc/hostname
hostname "$name"
#NOTE: NetworkManager may set it again after us based on DHCP or /etc/hostname, cf. `man NetworkManager.conf` @hostname-mode
#from /usr/lib/qubes/init/qubes-early-vm-config.sh
if [ -e /etc/debian_version ]; then
ipv4_localhost_re="127\.0\.1\.1"
else
ipv4_localhost_re="127\.0\.0\.1"
fi
sed -i "s/^\($ipv4_localhost_re\(\s.*\)*\s\).*$/\1${name}/" /etc/hosts
sed -i "s/^\(::1\(\s.*\)*\s\).*$/\1${name}/" /etc/hosts
fi
exit 0
```
Assuming that you're using `sys-net` as your network VM, your `sys-net` hostname should now be `PC-[number]` with a different `[number]` each time your `sys-net` is started.
Please note that the above script should _not_ be added to [/rw/config/rc.local](https://www.qubes-os.org/doc/config-files/)) as that is executed only _after_ the network fully started.