WireGuard extras

• This how-to describes the most common WireGuard tuning scenarios adapted for OpenWrt.
• Follow WireGuard server for server setup and WireGuard client for client setup.
• Follow WireGuard protocol for protocol-specific interface options.
• Follow Random generator to overcome low entropy issues.

• WireGuard for mobile/desktop/server
• WireGuard documentation
• WireGuard configuration examples

Install the necessary packages if you want to manage VPN settings and view VPN status using web interface.

# Install packages
opkg update
opkg install luci-proto-wireguard luci-app-wireguard
/etc/init.d/rpcd restart

• Navigate to LuCI → Network → Interfaces to configure WireGuard.
• Navigate to LuCI → Status → WireGuard Status to view WireGuard status.

Preserve default route to restore WAN connectivity when VPN is disconnected.

# Preserve default route
uci set network.wan.metric="100"
uci set network.wan6.metric="100"
uci commit network
/etc/init.d/network restart

Periodically re-resolve inactive peer hostnames for VPN peers with dynamic IP addresses.

# Periodically re-resolve inactive peers
cat << "EOF" >> /etc/crontabs/root
* * * * * /usr/bin/wireguard_watchdog
EOF
uci set system.@system[0].cronloglevel="9"
uci commit system
/etc/init.d/cron restart

Resolve the race condition with sysntpd service.

# Resolve race conditions
cat << "EOF" >> /etc/crontabs/root
* * * * * date -s 2030-01-01; /etc/init.d/sysntpd restart
EOF
uci set system.@system[0].cronloglevel="9"
uci commit system
/etc/init.d/cron restart

Implement plain routing between server side LAN and client side LAN assuming that:

• 192.168.1.0/24 - server side LAN
• 192.168.2.0/24 - client side LAN

Add route to client side LAN on VPN server.

uci set network.wgclient.route_allowed_ips="1"
uci add_list network.wgclient.allowed_ips="192.168.2.0/24"
uci commit network
/etc/init.d/network restart

Add route to server side LAN on VPN client.

uci set network.wgserver.route_allowed_ips="1"
uci add_list network.wgserver.allowed_ips="192.168.1.0/24"
uci commit network
/etc/init.d/network restart

Consider VPN network as private and assign VPN interface to LAN zone on VPN client.

uci del_list firewall.wan.network="vpn"
uci add_list firewall.lan.network="vpn"
uci commit firewall
/etc/init.d/firewall restart

Provide IPv6 site-to-site connectivity assuming that:

• fdf1:e8a1:8d3f:1::/64 - server side LAN
• fdf1:e8a1:8d3f:2::/64 - client side LAN

Add route to client side LAN on VPN server.

uci set network.lan.ip6assign="64"
uci set network.lan.ip6hint="1"
uci set network.vpn.ip6prefix="fdf1:e8a1:8d3f::/48"
uci add_list network.wgclient.allowed_ips="fdf1:e8a1:8d3f:2::/64"
uci commit network
/etc/init.d/network restart

Add route to server side LAN on VPN client.

uci set network.lan.ip6assign="64"
uci set network.lan.ip6hint="2"
uci set network.vpn.ip6prefix="fdf1:e8a1:8d3f::/48"
uci add_list network.wgserver.allowed_ips="fdf1:e8a1:8d3f:1::/64"
uci commit network
/etc/init.d/network restart

If you do not need to redirect all traffic to VPN. Disable gateway redirection on VPN client.

uci del_list network.wgserver.allowed_ips="0.0.0.0/0"
uci del_list network.wgserver.allowed_ips="::/0"
uci commit network
/etc/init.d/network restart

If VPN gateway is not your LAN gateway. Implement plain routing between LAN network and VPN network assuming that:

• 192.168.1.0/24 - LAN network
• 192.168.1.2/24 - VPN gateway
• 192.168.9.0/24 - VPN network

Add port forwarding for VPN server on LAN gateway.

uci -q delete firewall.wg
uci set firewall.wg="redirect"
uci set firewall.wg.name="Redirect-WireGuard"
uci set firewall.wg.src="wan"
uci set firewall.wg.src_dport="51820"
uci set firewall.wg.dest="lan"
uci set firewall.wg.dest_ip="192.168.1.2"
uci set firewall.wg.family="ipv4"
uci set firewall.wg.proto="udp"
uci set firewall.wg.target="DNAT"
uci commit firewall
/etc/init.d/firewall restart

Add route to VPN network via VPN gateway on LAN gateway.

uci -q delete network.vpn
uci set network.vpn="route"
uci set network.vpn.interface="lan"
uci set network.vpn.target="192.168.9.0/24"
uci set network.vpn.gateway="192.168.1.2"
uci commit network
/etc/init.d/network restart

Utilize DNS over VPN to prevent DNS leak.

Disable peer DNS and configure a VPN-routed DNS provider on OpenWrt client.

Modify the VPN connection using NetworkManager on Linux desktop client.

nmcli connection modify id VPN_CON ipv4.dns-search ~. ipv6.dns-search ~. ipv4.dns-priority -50 ipv6.dns-priority -50

Prevent traffic leak on OpenWrt client isolating VPN interface in a separate firewall zone.

uci rename firewall.@forwarding[0]="lan_wan"
uci set firewall.lan_wan.enabled="0"
uci -q delete firewall.vpn
uci set firewall.vpn="zone"
uci set firewall.vpn.name="vpn"
uci set firewall.vpn.input="REJECT"
uci set firewall.vpn.output="ACCEPT"
uci set firewall.vpn.forward="REJECT"
uci set firewall.vpn.masq="1"
uci set firewall.vpn.mtu_fix="1"
uci add_list firewall.vpn.network="vpn"
uci del_list firewall.wan.network="vpn"
uci -q delete firewall.lan_vpn
uci set firewall.lan_vpn="forwarding"
uci set firewall.lan_vpn.src="lan"
uci set firewall.lan_vpn.dest="vpn"
uci commit firewall
/etc/init.d/firewall restart

Set up multi-client VPN server. Generate client keys and profiles. Configure VPN peers.

# Configuration parameters
WG_IDS="wgserver wgclient wglaptop wgmobile"
WG_PKI="."
WG_IF="vpn"
WG_PORT="$(uci get network.${WG_IF}.listen_port)"
WG_ADDRS="$(uci get network.${WG_IF}.addresses)"
WG_ADDR="${WG_ADDRS%% *}"
WG_ADDR6="${WG_ADDRS##* }"
 
# Fetch WAN IP address
. /lib/functions/network.sh
network_flush_cache
network_find_wan NET_IF
network_get_ipaddr NET_ADDR "${NET_IF}"
WG_SERV="${NET_ADDR}"
 
# Fetch FQDN from DDNS client
NET_FQDN="$(uci -q get "$(uci -q show ddns \
| sed -n -e "/\.enabled='1'$/s//.lookup_host/p" \
| sed -n -e "1p")")"
if [ -n "${NET_FQDN}" ]
then WG_SERV="${NET_FQDN}"
fi
 
# Generate client keys
umask go=
mkdir -p ${WG_PKI}
for WG_ID in ${WG_IDS#* }
do
if [ ! -e "${WG_PKI}/${WG_ID}.pub" ]
then wg genkey \
| tee ${WG_PKI}/${WG_ID}.key \
| wg pubkey > ${WG_PKI}/${WG_ID}.pub
fi
if [ ! -e "${WG_PKI}/${WG_ID}.psk" ]
then wg genpsk > ${WG_PKI}/${WG_ID}.psk
fi
done
 
# Generate client profiles
WG_SFX="1"
for WG_ID in ${WG_IDS#* }
do
let WG_SFX++
cat << EOF > ${WG_PKI}/${WG_ID}.conf
[Interface]
Address = ${WG_ADDR%.*}.${WG_SFX}/24, ${WG_ADDR6%:*}:${WG_SFX}/64
PrivateKey = $(cat ${WG_PKI}/${WG_ID}.key)
DNS = ${WG_ADDR%/*}, ${WG_ADDR6%/*}
[Peer]
PublicKey = $(cat ${WG_PKI}/${WG_IDS%% *}.pub)
PresharedKey = $(cat ${WG_PKI}/${WG_ID}.psk)
PersistentKeepalive = 25
AllowedIPs = 0.0.0.0/0, ::/0
Endpoint = ${WG_SERV}:${WG_PORT}
EOF
done
ls ${WG_PKI}/*.conf
 
# Back up client profiles
cat << EOF >> /etc/sysupgrade.conf
/root
EOF
 
# Add VPN peers
WG_SFX="1"
for WG_ID in ${WG_IDS#* }
do
let WG_SFX++
uci -q delete network.${WG_ID}
uci set network.${WG_ID}="wireguard_${WG_IF}"
uci set network.${WG_ID}.public_key="$(cat ${WG_PKI}/${WG_ID}.pub)"
uci set network.${WG_ID}.preshared_key="$(cat ${WG_PKI}/${WG_ID}.psk)"
uci add_list network.${WG_ID}.allowed_ips="${WG_ADDR%.*}.${WG_SFX}/32"
uci add_list network.${WG_ID}.allowed_ips="${WG_ADDR6%:*}:${WG_SFX}/128"
done
uci commit network
/etc/init.d/network restart

Perform OpenWrt backup. Extract client profiles from the archive and import them to your clients.

Automated VPN server installation and client profiles generation.

opkg update
opkg install curl
URL="https://openwrt.org/_export/code/docs/guide-user/services/vpn/wireguard"
cat << EOF > wireguard-server.sh
$(curl "${URL}/server?codeblock=0")
$(curl "${URL}/server?codeblock=1")
$(curl "${URL}/server?codeblock=2")
$(curl "${URL}/server?codeblock=3")
sleep 10
$(curl "${URL}/extras?codeblock=14")
EOF
sh wireguard-server.sh