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 when using site-to-site connection.

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

Disable gateway redirection on VPN client configured with PBR.

uci -q delete network.wgserver.route_allowed_ips
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

Provide DNS for VPN clients in P2P topology on OpenWrt server.

Utilize DNS over VPN to prevent DNS leak on VPN client.

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
$(pwd ${WG_PKI})
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 libustream-mbedtls
URL="https://openwrt.org/_export/code/docs/guide-user/services/vpn/wireguard"
cat << EOF > wireguard-server.sh
$(uclient-fetch -O - "${URL}/server?codeblock=0")
$(uclient-fetch -O - "${URL}/server?codeblock=1")
$(uclient-fetch -O - "${URL}/server?codeblock=2")
$(uclient-fetch -O - "${URL}/server?codeblock=3")
sleep 10
$(uclient-fetch -O - "${URL}/extras?codeblock=15")
EOF
sh wireguard-server.sh