snippets/linux/wireguard-instant.sh

#!/bin/bash

### References
# https://wiki.archlinux.org/title/WireGuard

### Installation
# Install wireguard tools and QR-Code generator
apt-get install --yes wireguard qrencode

### Variables
network='192.168.130.1/24'
confdir='/etc/wireguard'

### Create key material
cd $confdir
wgkeypair() { wg genkey | (umask 0077 && tee   $1.key) | wg pubkey > $1.pub; }
wgpsk()     { wg genpsk | (umask 0077 && cat > $1.psk) } 
wgkeypair host
peers="dspx4 zino2"
for peer in $peers; do wgkeypair $peer && wgpsk $peer; done

### Configuration
# Setup wireguard network interface
ip link add dev wg0 type wireguard
ip addr add $network dev wg0
wg set wg0 listen-port 51871 private-key $confdir/host.key 

wgsetpeer() {
peer=$1
ip=$2
wg set wg0                                 \
   peer           `cat $confdir/$peer.pub` \
   preshared-key  $confdir/$peer.psk       \
   allowed-ips    $ip
ip link set wg0 up

cat >$confdir/$peer.conf <<EOL
# Client config for $peer
[Interface]
PrivateKey = `cat $confdir/$peer.key`
Address = $ip
DNS = 8.8.8.8
 
[Peer]
PublicKey = `cat $confdir/host.pub`
AllowedIPs = 0.0.0.0/0
Endpoint = blue.s-up.net:51871
PersistentKeepalive = 15
PresharedKey = `cat $confdir/$peer.psk`
EOL

qrencode  -t ANSIUTF8 -r $confdir/$peer.conf
}

wgsetpeer dspx4 192.168.130.2

# https://www.cyberciti.biz/faq/how-to-set-up-wireguard-firewall-rules-in-linux/
iptables -t nat -I POSTROUTING 1 -s 192.168.130.0/24 -o ens3 -j MASQUERADE
iptables -I INPUT 1 -i wg0 -j ACCEPT
iptables -I FORWARD 1 -i ens3 -o wg0 -j ACCEPT
iptables -I FORWARD 1 -i wg0 -o ens3 -j ACCEPT
iptables -I INPUT 1 -i eth0 -p udp --dport 51871 -j ACCEPT
sysctl -w net.ipv4.ip_forward=1