Admin Guide: Using Liquid with WireGuard VPN and Tails Clients

Liquid using WireGuard and Tails

Work in progress

---

Liquid can be used in an isolated environment accessible using a WireGuard VPN only. Moreover, a slightly more paranoid setup is using Tails accessing this isolated service.

Consider the generic instruction to use Liquid on VPN, first.

Setting up the server-side WireGuard VPN

Based on top of the WireGuard Quick Start you may want to use the WireGuard installer provided by angristan at GitHub. Some unofficial WireGuard Documentation is very useful for more advanced setups.

Install WireGuard

sudo apt install wireguard

Create a private/public key pair using:

cd /etc/wireguard
umask 077
wg genkey | tee privatekey | wg pubkey > publickey

Create a configuration file at /etc/wireguard/wg0.conf using a private IP range like 10.11.12.0/24:

[Interface]
Address = 10.11.12.1/32
SaveConfig = true
PostUp = iptables -t nat -I POSTROUTING -o eth0 -j MASQUERADE
PreDown = iptables -t nat -D POSTROUTING -o eth0 -j MASQUERADE
ListenPort = 51820
PrivateKey = **private server key**

[Peer]
PublicKey = **public client key**
AllowedIPs = 10.11.12.2/32

Start and stop using wg-quick

# start
sudo wg-quick up wg0
# stop
sudo wg-quick down wg0

Adding clients

You'll need the public key for every peer and assign an individual IP used on the client side. On the client install WireGuard and create a configuration file /etc/wireguard/wg0.conf:

[Interface]
PrivateKey = **private client key**
Address = 10.11.12.2/32

[Peer]
PublicKey = **public server key**
AllowedIPs = 10.11.12.0/24
Endpoint = **public server ip**:51820
PersistentKeepalive = 25

Add the client peer on the server side using:

# add peer
sudo wg set wg0 peer **public client key** allowed-ips 10.11.12.2
# remove peer
sudo wg set wg0 peer **public client key** remove

Provision Tails to be a peer

Assuming: an existing Tails Persistence layer, a configured Administration user and an enabled Unsafe Browser, start installing WireGuard using sudo apt update && sudo apt install wireguard, first. Answer Install Every Time when prompted. Add a client config as above.

Allow incoming and outgoing udp packets by editing /etc/ferm/ferm.conf:

domain ip {
    table filter {
        chain INPUT {
            policy DROP;

            daddr (**public server ip**/32) {
                proto udp ACCEPT;
            }
# ...
        chain OUTPUT {
            policy DROP;

            daddr (**public server ip**/32) {
                proto udp ACCEPT;
            }
# ...
}

Apply changes with service ferm restart.

Additional configs for local DNS and Certificates using the Unsafe Browser

Add local DNS setting applying a patch to /usr/local/sbin/usafe-browser:

--- /usr/local/sbin/unsafe-browser	2022-12-19 09:43:26.000000000 +0000
+++ unsafe-browser	2023-01-12 12:24:06.980003349 +0000
@@ -152,6 +152,8 @@
 echo '127.0.0.42 firefox.settings.services.mozilla.com' \
      >> "${CHROOT}"/etc/hosts
 
+echo '10.11.12.1      **servername**.home.arpa hoover.**servername**.home.arpa dokuwiki.**servername**.home.arpa rocketchat.**servername**.home.arpa nextcloud.**servername**.home.arpa codimd.**servername**.home.arpa wikijs.**servername**.home.arpa' >> "${CHROOT}"/etc/hosts
+
 echo "* Starting Unsafe Browser"
 # Do not localize the 5th argument: it becomes WM_CLASS and then GNOME
 # displays the localized app name found in the matching .desktop file;