WireGuard
From the WireGuard project homepage:
- WireGuard is an extremely simple yet fast and modern VPN that utilizes state-of-the-art cryptography. It aims to be faster, simpler, leaner, and more useful than IPsec, while avoiding the massive headache. It intends to be considerably more performant than OpenVPN. WireGuard is designed as a general purpose VPN for running on embedded interfaces and super computers alike, fit for many different circumstances. Initially released for the Linux kernel, it is now cross-platform (Windows, macOS, BSD, iOS, Android) and widely deployable.
A rough introduction to the main concepts used in this article can be found on WireGuard's project homepage. WireGuard is in the Linux kernel since March 2020.
Installation
Install the wireguard-tools package for userspace utilities.
Alternatively, various network managers provide support for WireGuard, provided that peer keys are available. See #Persistent configuration for details.
Graphical clients
- Qomui — OpenVPN GUI with advanced features and support for multiple providers.
Usage
The commands below demonstrate how to set up a basic tunnel between two or more peers with the following settings:
| External (public) addresses | Internal IP addresses | Port | ||||
|---|---|---|---|---|---|---|
| Domain name | IPv4 address | IPv6 address | IPv4 address | IPv6 address | ||
| Peer A | 198.51.100.101 | 2001:db8:a85b:70a:ffd4:ec1b:4650:a001 | 10.0.0.1/24 | fdc9:281f:04d7:9ee9::1/64 | UDP/51871 | |
| Peer B | peer-b.example | 203.0.113.102 | 2001:db8:40f0:147a:80ad:3e88:f8e9:b002 | 10.0.0.2/24 | fdc9:281f:04d7:9ee9::2/64 | UDP/51902 |
| Peer C | dynamic | dynamic | 10.0.0.3/24 | fdc9:281f:04d7:9ee9::3/64 | UDP/51993 | |
The external addresses should already exist. For example, if ICMP echo requests are not blocked, peer A should be able to ping peer B via its public IP address(es) and vice versa.
The internal addresses will be new addresses, created either manually using the ip(8) utility or by network management software, which will be used internally within the new WireGuard network. The following examples will use 10.0.0.0/24 and fdc9:281f:04d7:9ee9::/64 as the internal network. The /24 and /64 in the IP addresses is the CIDR.
Key generation
Create a private and public key for each peer. If connecting dozens of peers optionally consider a vanity keypair to personalize the Base64 encoded public key string. See #Vanity keys.
To create a private key run:
$ (umask 0077; wg genkey > peer_A.key)
To create a public key:
$ wg pubkey < peer_A.key > peer_A.pub
Alternatively, do this all at once:
$ wg genkey | (umask 0077 && tee peer_A.key) | wg pubkey > peer_A.pub
One can also generate a pre-shared key to add an additional layer of symmetric-key cryptography to be mixed into the already existing public-key cryptography, for post-quantum resistance. A pre-shared key should be generated for each peer pair and should not be reused. For example, three interconnected peers, A, B, and, C will need three separate pre-shared keys, one for each peer pair.
Generate a pre-shared key for each peer pair using the following command:
$ wg genpsk > peer_A-peer_B.psk $ wg genpsk > peer_A-peer_C.psk $ wg genpsk > peer_B-peer_C.psk
Vanity keys
Currently, WireGuard does not support comments or attaching human-memorable names to keys. This makes identifying the key's owner difficult particularly when multiple keys are in use. One solution is to generate a public key that contains some familiar characters (perhaps the first few letters of the owner's name or of the hostname etc.), wireguard-vanity-addressAUR does this.
Manual configuration
Peer setup
Manual setup is accomplished by using ip(8) and wg(8).
Peer A setup:
In this example peer A will listen on UDP port 51871 and will accept connection from peer B and C.
# ip link add dev wg0 type wireguard # ip addr add 10.0.0.1/24 dev wg0 # ip addr add fdc9:281f:04d7:9ee9::1/64 dev wg0 # wg set wg0 listen-port 51871 private-key /path/to/peer_A.key # wg set wg0 peer PEER_B_PUBLIC_KEY preshared-key /path/to/peer_A-peer_B.psk endpoint peer-b.example:51902 allowed-ips 10.0.0.2/32,fdc9:281f:04d7:9ee9::2/128 # wg set wg0 peer PEER_C_PUBLIC_KEY preshared-key /path/to/peer_A-peer_C.psk allowed-ips 10.0.0.3/32,fdc9:281f:04d7:9ee9::3/128 # ip link set wg0 up
PEER_X_PUBLIC_KEY should be the contents of peer_X.pub.
The keyword allowed-ips is a list of addresses that will get routed to the peer. Make sure to specify at least one address range that contains the WireGuard connection's internal IP address(es).
Peer B setup:
# ip link add dev wg0 type wireguard # ip addr add 10.0.0.2/24 dev wg0 # ip addr add fdc9:281f:04d7:9ee9::2/64 dev wg0 # wg set wg0 listen-port 51902 private-key /path/to/peer_B.key # wg set wg0 peer PEER_A_PUBLIC_KEY preshared-key /path/to/peer_A-peer_B.psk endpoint 198.51.100.101:51871 allowed-ips 10.0.0.1/32,fdc9:281f:04d7:9ee9::1/128 # wg set wg0 peer PEER_C_PUBLIC_KEY preshared-key /path/to/peer_B-peer_C.psk allowed-ips 10.0.0.3/32,fdc9:281f:04d7:9ee9::3/128 # ip link set wg0 up
Peer C setup:
# ip link add dev wg0 type wireguard # ip addr add 10.0.0.3/24 dev wg0 # ip addr add fdc9:281f:04d7:9ee9::3/64 dev wg0 # wg set wg0 listen-port 51993 private-key /path/to/peer_C.key # wg set wg0 peer PEER_A_PUBLIC_KEY preshared-key /path/to/peer_A-peer_C.psk endpoint 198.51.100.101:51871 allowed-ips 10.0.0.1/32,fdc9:281f:04d7:9ee9::1/128 # wg set wg0 peer PEER_B_PUBLIC_KEY preshared-key /path/to/peer_B-peer_C.psk endpoint peer-b.example:51902 allowed-ips 10.0.0.2/32,fdc9:281f:04d7:9ee9::2/128 # ip link set wg0 up
Additional routes
To establish connections more complicated than point-to-point, additional setup is necessary.
Point-to-site
To access the network of a peer, specify the network subnet(s) in allowed-ips in the configuration of the peers who should be able to connect to it. E.g. allowed-ips 10.0.0.2/32,fdc9:281f:04d7:9ee9::2/128,192.168.35.0/24,fd7b:d0bd:7a6e::/64.
Make sure to also set up the routing table with ip-route(8). E.g.:
# ip route add 192.168.35.0/24 dev wg0 # ip route add fd7b:d0bd:7a6e::/64 dev wg0
Site-to-point
If the intent is to connect a device to a network with WireGuard peer(s), set up routes on each device so they know that the peer(s) are reachable via the device.
Enable IP forwarding on the peer through which other devices on the network will connect to WireGuard peer(s):
# sysctl -w net.ipv4.ip_forward=1 # sysctl -w net.ipv6.conf.all.forwarding=1
See sysctl#Configuration for instructions on how to set the sysctl parameters on boot.
Site-to-site
To connect two (or more) networks, apply both #Point-to-site and #Site-to-point on all sites.
Routing all traffic over WireGuard
DNS
To use a peer as a DNS server, add its WireGuard tunnel IP address(es) to /etc/resolv.conf. For example, to use peer B as the DNS server:
/etc/resolv.conf
nameserver fdc9:281f:04d7:9ee9::2 nameserver 10.0.0.2
Basic checkups
Invoking the wg(8) command without parameters will give a quick overview of the current configuration.
As an example, when peer A has been configured we are able to see its identity and its associated peers:
# wg
interface: wg0 public key: UguPyBThx/+xMXeTbRYkKlP0Wh/QZT3vTLPOVaaXTD8= private key: (hidden) listening port: 51871 peer: 9jalV3EEBnVXahro0pRMQ+cHlmjE33Slo9tddzCVtCw= endpoint: 203.0.113.102:51902 allowed ips: 10.0.0.2/32, fdc9:281f:04d7:9ee9::2 peer: 2RzKFbGMx5g7fG0BrWCI7JIpGvcwGkqUaCoENYueJw4= endpoint: 192.0.2.103:51993 allowed ips: 10.0.0.3/32, fdc9:281f:04d7:9ee9::3
At this point one could reach the end of the tunnel. If the peers do not block ICMP echo requests, try pinging a peer to test the connection between them.
Using ICMPv4:
$ ping 10.0.0.2
Using ICMPv6:
$ ping fdc9:281f:04d7:9ee9::2
After transferring some data between peers, the wg utility will show additional information:
# wg
interface: wg0 public key: UguPyBThx/+xMXeTbRYkKlP0Wh/QZT3vTLPOVaaXTD8= private key: (hidden) listening port: 51871 peer: 9jalV3EEBnVXahro0pRMQ+cHlmjE33Slo9tddzCVtCw= endpoint: 203.0.113.102:51902 allowed ips: 10.0.0.2/32, fdc9:281f:04d7:9ee9::2 latest handshake: 5 seconds ago transfer: 1.24 KiB received, 1.38 KiB sent peer: 2RzKFbGMx5g7fG0BrWCI7JIpGvcwGkqUaCoENYueJw4= allowed ips: 10.0.0.3/32, fdc9:281f:04d7:9ee9::3
Persistent configuration
Persistent configuration can be achieved using wg-quick@.service, which is shipped with wireguard-tools, or using a network manager. Network managers that support WireGuard are systemd-networkd, netctl[2], NetworkManager and ConnMan[3].
-
netctl relies on wg(8) from wireguard-tools and
/etc/wireguard/interfacename.confconfiguration files for establishing WireGuard connections. - ConnMan has a very limited support for WireGuard. It can connect to only one peer.[4]
wg-quick
wg-quick(8) configures WireGuard tunnels using configuration files from /etc/wireguard/interfacename.conf.
The current WireGuard configuration can be saved by utilizing the wg(8) utility's showconf command. For example:
# wg showconf wg0 > /etc/wireguard/wg0.conf
To start a tunnel with a configuration file, use
# wg-quick up interfacename
or use the systemd service—wg-quick@interfacename.service. To start the tunnel at boot, enable the unit.
- Users configuring the WireGuard interface using wg-quick, should make sure that no other network management software tries to manage it. To use NetworkManager and to not configure WireGuard interfaces with it, see #Routes are periodically reset.
-
wg-quick adds additional configuration options to the configuration file format thus making it incompatible with wg(8) § CONFIGURATION FILE FORMAT. See the wg-quick(8) § CONFIGURATION man page for the configuration values in question. A wg-compatible configuration file can be produced by using
wg-quick strip. - wg-quick does not provide a way to instruct resolvconf to set the WireGuard interface as private. Even if there are search domains specified, all DNS queries from the system, not just those that match the search domains, will be sent to the DNS servers which are set in the WireGuard configuration.
Peer A setup:
/etc/wireguard/wg0.conf
[Interface] Address = 10.0.0.1/24, fdc9:281f:04d7:9ee9::1/64 ListenPort = 51871 PrivateKey = PEER_A_PRIVATE_KEY MTU = 1420 [Peer] PublicKey = PEER_B_PUBLIC_KEY PresharedKey = PEER_A-PEER_B-PRESHARED_KEY AllowedIPs = 10.0.0.2/32, fdc9:281f:04d7:9ee9::2/128 Endpoint = peer-b.example:51902 [Peer] PublicKey = PEER_C_PUBLIC_KEY PresharedKey = PEER_A-PEER_C-PRESHARED_KEY AllowedIPs = 10.0.0.3/32, fdc9:281f:04d7:9ee9::3/128
- To route all traffic through the tunnel to a specific peer, add the default route (
0.0.0.0/0for IPv4 and::/0for IPv6) toAllowedIPs. E.g.AllowedIPs = 0.0.0.0/0, ::/0. wg-quick will automatically take care of setting up correct routing and fwmark[5] so that networking still functions. - To use a peer as a DNS server, set
DNS = wireguard_internal_ip_address_of_peerin the[Interface]section. Search domains are also set with theDNS =option. Separate all values in the list with commas.
Peer B setup:
/etc/wireguard/wg0.conf
[Interface] Address = 10.0.0.2/24, fdc9:281f:04d7:9ee9::2/64 ListenPort = 51902 PrivateKey = PEER_B_PRIVATE_KEY MTU = 1420 [Peer] PublicKey = PEER_A_PUBLIC_KEY PresharedKey = PEER_A-PEER_B-PRESHARED_KEY AllowedIPs = 10.0.0.1/32, fdc9:281f:04d7:9ee9::1/128 Endpoint = 198.51.100.101:51871 [Peer] PublicKey = PEER_C_PUBLIC_KEY PresharedKey = PEER_B-PEER_C-PRESHARED_KEY AllowedIPs = 10.0.0.3/32, fdc9:281f:04d7:9ee9::3/128
Peer C setup:
/etc/wireguard/wg0.conf
[Interface] Address = 10.0.0.3/24, fdc9:281f:04d7:9ee9::3/64 ListenPort = 51993 PrivateKey = PEER_C_PRIVATE_KEY MTU = 1420 [Peer] PublicKey = PEER_A_PUBLIC_KEY PresharedKey = PEER_A-PEER_C-PRESHARED_KEY AllowedIPs = 10.0.0.1/32, fdc9:281f:04d7:9ee9::1/128 Endpoint = 198.51.100.101:51871 [Peer] PublicKey = PEER_B_PUBLIC_KEY PresharedKey = PEER_B-PEER_C-PRESHARED_KEY AllowedIPs = 10.0.0.2/32, fdc9:281f:04d7:9ee9::2/128 Endpoint = peer-b.example:51902
systemd-networkd
systemd-networkd has native support for setting up WireGuard interfaces. An example is provided in the systemd.netdev(5) § EXAMPLES man page.
- Routing all DNS over WireGuard (i.e.
Domains=~.) will prevent the DNS resolution of endpoints. - systemd-networkd does not automatically create routes for subnets specified in AllowedIPs. See systemd issue 14176. This will not affect the connectivity between peers since they exist in the subnet that is specified with the
Address=option in the .network file.
Peer A setup:
/etc/systemd/network/99-wg0.netdev
[NetDev] Name=wg0 Kind=wireguard Description=WireGuard tunnel wg0 [WireGuard] ListenPort=51871 PrivateKey=PEER_A_PRIVATE_KEY [WireGuardPeer] PublicKey=PEER_B_PUBLIC_KEY PresharedKey=PEER_A-PEER_B-PRESHARED_KEY AllowedIPs=10.0.0.2/32 AllowedIPs=fdc9:281f:04d7:9ee9::2/128 Endpoint=peer-b.example:51902 [WireGuardPeer] PublicKey=PEER_C_PUBLIC_KEY PresharedKey=PEER_A-PEER_C-PRESHARED_KEY AllowedIPs=10.0.0.3/32 AllowedIPs=fdc9:281f:04d7:9ee9::3/128
/etc/systemd/network/99-wg0.network
[Match] Name=wg0 [Network] Address=10.0.0.1/24 Address=fdc9:281f:04d7:9ee9::1/64
- To use a peer as a DNS server, specify its WireGuard tunnel's IP address(es) in the .network file using the
DNS=option. For search domains use theDomains=option. See systemd.network(5) § [NETWORK] SECTION OPTIONS for details. - To use a peer as the only DNS server, then in the .network file's
[Network]section setDNSDefaultRoute=trueand add~.toDomains=option. - To route additional subnets add them as
[Route]sections in the .network file. For example:
/etc/systemd/network/99-wg0.network
... [Route] Destination=192.168.35.0/24 Scope=link [Route] Destination=fd7b:d0bd:7a6e::/64 Scope=link
# chown root:systemd-network /etc/systemd/network/99-*.netdev # chmod 0640 /etc/systemd/network/99-*.netdev
Peer B setup:
/etc/systemd/network/99-wg0.netdev
[NetDev] Name=wg0 Kind=wireguard Description=WireGuard tunnel wg0 [WireGuard] ListenPort=51902 PrivateKey=PEER_B_PRIVATE_KEY [WireGuardPeer] PublicKey=PEER_A_PUBLIC_KEY PresharedKey=PEER_A-PEER_B-PRESHARED_KEY AllowedIPs=10.0.0.1/32 AllowedIPs=fdc9:281f:04d7:9ee9::1/128 Endpoint=198.51.100.101:51871 [WireGuardPeer] PublicKey=PEER_C_PUBLIC_KEY PresharedKey=PEER_B-PEER_C-PRESHARED_KEY AllowedIPs=10.0.0.3/32 AllowedIPs=fdc9:281f:04d7:9ee9::3/128
/etc/systemd/network/99-wg0.network
[Match] Name=wg0 [Network] Address=10.0.0.2/24 Address=fdc9:281f:04d7:9ee9::2/64
Peer C setup:
/etc/systemd/network/99-wg0.netdev
[NetDev] Name=wg0 Kind=wireguard Description=WireGuard tunnel wg0 [WireGuard] ListenPort=51993 PrivateKey=PEER_C_PRIVATE_KEY [WireGuardPeer] PublicKey=PEER_A_PUBLIC_KEY PresharedKey=PEER_A-PEER_C-PRESHARED_KEY AllowedIPs=10.0.0.1/32 AllowedIPs=fdc9:281f:04d7:9ee9::1/128 Endpoint=198.51.100.101:51871 [WireGuardPeer] PublicKey=PEER_B_PUBLIC_KEY PresharedKey=PEER_B-PEER_C-PRESHARED_KEY AllowedIPs=10.0.0.2/32 AllowedIPs=fdc9:281f:04d7:9ee9::2/128 Endpoint=peer-b.example:51902
/etc/systemd/network/99-wg0.network
[Match] Name=wg0 [Network] Address=10.0.0.3/24 Address=fdc9:281f:04d7:9ee9::3/64
systemd-networkd: routing all traffic over WireGuard
In this example Peer B connects to peer A with public IP address. Peer B routes all its traffic over WireGuard tunnel and uses Peer A for handling DNS requests.
Peer A setup
/etc/systemd/network/99-wg0.netdev
[NetDev] Name=wg0 Kind=wireguard Description=WireGuard tunnel wg0 [WireGuard] ListenPort=51871 PrivateKey=PEER_A_PRIVATE_KEY [WireGuardPeer] PublicKey=PEER_B_PUBLIC_KEY PresharedKey=PEER_A-PEER_B-PRESHARED_KEY AllowedIPs=10.0.0.2/32
/etc/systemd/network/99-wg0.network
[Match] Name=wg0 [Network] Address=10.0.0.1/24
Assumes ufw, but you could do the same with iptables by using the rules outlined in the Server config section:
$ ufw route allow in on wg0 out on enp5s0
/etc/ufw/before.rules
*nat :POSTROUTING ACCEPT [0:0] -A POSTROUTING -s 10.0.0.0/24 -o enp5s0 -j MASQUERADE COMMIT
Peer B setup:
/etc/systemd/network/99-wg0.netdev
[NetDev] Name=wg0 Kind=wireguard Description=WireGuard tunnel wg0 [WireGuard] ListenPort=51902 PrivateKey=PEER_B_PRIVATE_KEY FirewallMark=0x8888 [WireGuardPeer] PublicKey=PEER_A_PUBLIC_KEY PresharedKey=PEER_A-PEER_B-PRESHARED_KEY AllowedIPs=0.0.0.0/0 Endpoint=198.51.100.101:51871
/etc/systemd/network/50-wg0.network
[Match] Name=wg0 [Network] Address=10.0.0.2/24 DNS=10.0.0.1 DNSDefaultRoute=true Domains=~. [RoutingPolicyRule] FirewallMark=0x8888 InvertRule=true Table=1000 Priority=10 [Route] Gateway=10.0.0.1 GatewayOnLink=true Table=1000
Netctl
Netctl has native support for setting up WireGuard interfaces. A typical set of WireGuard netctl profile configuration files would look like this:
Peer A setup:
/etc/netctl/wg0
Description="WireGuard tunnel on peer A"
Interface=wg0
Connection=wireguard
WGConfigFile=/etc/wireguard/wg0.conf
IP=static
Address=('10.0.0.1/24')
/etc/wireguard/wg0.conf
[Interface] ListenPort = 51871 PrivateKey = PEER_A_PRIVATE_KEY [Peer] PublicKey = PEER_B_PUBLIC_KEY AllowedIPs = 10.0.0.2/32 Endpoint = peer-b.example:51902 [Peer] PublicKey = PEER_C_PUBLIC_KEY AllowedIPs = 10.0.0.3/32
Peer B setup:
/etc/netctl/wg0
Description="WireGuard tunnel on peer B"
Interface=wg0
Connection=wireguard
WGConfigFile=/etc/wireguard/wg0.conf
IP=static
Address=('10.0.0.2/24')
/etc/wireguard/wg0.conf
[Interface] ListenPort = 51902 PrivateKey = PEER_B_PRIVATE_KEY [Peer] PublicKey = PEER_A_PUBLIC_KEY AllowedIPs = 10.0.0.1/32 Endpoint = peer-a.example:51871 [Peer] PublicKey = PEER_C_PUBLIC_KEY AllowedIPs = 10.0.0.3/32
Peer C setup:
/etc/netctl/wg0
Description="WireGuard tunnel on peer C"
Interface=wg0
Connection=wireguard
WGConfigFile=/etc/wireguard/wg0.conf
IP=static
Address=('10.0.0.3/24')
/etc/wireguard/wg0.conf
[Interface] ListenPort = 51993 PrivateKey = PEER_C_PRIVATE_KEY [Peer] PublicKey = PEER_A_PUBLIC_KEY AllowedIPs = 10.0.0.1/32 Endpoint = peer-a.example:51871 [Peer] PublicKey = PEER_B_PUBLIC_KEY AllowedIPs = 10.0.0.2/32 Endpoint = peer-b.example:51902
Then start and/or enable wg0 interface on every participating peer as needed, ie.
# netctl start wg0
To implement persistent site-to-peer, peer-to-site or site-to-site type of connection with WireGuard and Netctl, just add appropriate Routes= line into the netctl profile config file and add this network to AllowedIPs in the WireGuard profile, eg. Routes=('192.168.10.0/24 dev wg0') in the /etc/netctl/wg0 and AllowedIPs=10.0.0.1/32, 192.168.10.0/24 in /etc/wireguard/wg0.conf and then do not forget to enable IP forwarding.
NetworkManager
NetworkManager has native support for setting up WireGuard interfaces. For all details about WireGuard usage in NetworkManager, read Thomas Haller's blog post—WireGuard in NetworkManager.
# nmcli connection import type wireguard file /etc/wireguard/wg0.conf
The following examples configure WireGuard via the keyfile format .nmconnection files. See nm-settings-keyfile(5) and nm-settings(5) for an explanation on the syntax and available options.
Peer A setup:
/etc/NetworkManager/system-connections/wg0.nmconnection
[connection] id=wg0 type=wireguard interface-name=wg0 [wireguard] listen-port=51871 private-key=PEER_A_PRIVATE_KEY private-key-flags=0 [wireguard-peer.PEER_B_PUBLIC_KEY] endpoint=peer-b.example:51902 preshared-key=PEER_A-PEER_B-PRESHARED_KEY preshared-key-flags=0 allowed-ips=10.0.0.2/32;fdc9:281f:04d7:9ee9::2/128; [wireguard-peer.PEER_C_PUBLIC_KEY] preshared-key=PEER_A-PEER_C-PRESHARED_KEY preshared-key-flags=0 allowed-ips=10.0.0.3/32;fdc9:281f:04d7:9ee9::3/128; [ipv4] address1=10.0.0.1/24 method=manual [ipv6] address1=fdc9:281f:04d7:9ee9::1/64 method=manual
- To route all traffic through the tunnel to a specific peer, add the default route (
0.0.0.0/0for IPv4 and::/0for IPv6) towireguard-peer.PEER_X_PUBLIC_KEY.allowed-ips. E.g.wireguard-peer.PEER_B_PUBLIC_KEY.allowed-ips=0.0.0.0/0;::/0;. Special handling of the default route in WireGuard connections is supported since NetworkManager 1.20.0. - To use a peer as a DNS server, specify its WireGuard tunnel's IP address(es) with the
ipv4.dnsandipv6.dnssettings. Search domains can be specified with theipv4.dns-search=andipv6.dns-search=options. See nm-settings(5) for more details. For example, using the keyfile format:
... [ipv4] ... dns=10.0.0.2; dns-search=corp; ... [ipv6] ... dns=fdc9:281f:04d7:9ee9::2; dns-search=corp; ...
To use a peer as the only DNS server, set a negative DNS priority (e.g. dns-priority=-1) and add ~. to the dns-search= settings.
Peer B setup:
/etc/NetworkManager/system-connections/wg0.nmconnection
[connection] id=wg0 type=wireguard interface-name=wg0 [wireguard] listen-port=51902 private-key=PEER_B_PRIVATE_KEY private-key-flags=0 [wireguard-peer.PEER_A_PUBLIC_KEY] endpoint=198.51.100.101:51871 preshared-key=PEER_A-PEER_B-PRESHARED_KEY preshared-key-flags=0 allowed-ips=10.0.0.1/32;fdc9:281f:04d7:9ee9::1/128; [wireguard-peer.PEER_C_PUBLIC_KEY] preshared-key=PEER_B-PEER_C-PRESHARED_KEY preshared-key-flags=0 allowed-ips=10.0.0.3/32;fdc9:281f:04d7:9ee9::3/128; [ipv4] address1=10.0.0.2/24 method=manual [ipv6] address1=fdc9:281f:04d7:9ee9::2/64 method=manual
Peer C setup:
/etc/NetworkManager/system-connections/wg0.nmconnection
[connection] id=wg0 type=wireguard interface-name=wg0 [wireguard] listen-port=51993 private-key=PEER_C_PRIVATE_KEY private-key-flags=0 [wireguard-peer.PEER_A_PUBLIC_KEY] endpoint=198.51.100.101:51871 preshared-key=PEER_A-PEER_C-PRESHARED_KEY preshared-key-flags=0 allowed-ips=10.0.0.1/32;fdc9:281f:04d7:9ee9::1/128; [wireguard-peer.PEER_B_PUBLIC_KEY] endpoint=peer-b.example:51902 preshared-key=PEER_B-PEER_C-PRESHARED_KEY preshared-key-flags=0 allowed-ips=10.0.0.2/32;fdc9:281f:04d7:9ee9::2/128; [ipv4] address1=10.0.0.3/24 method=manual [ipv6] address1=fdc9:281f:04d7:9ee9::3/64 method=manual
Specific use-case: VPN server
The purpose of this section is to set up a WireGuard "server" and generic "clients" to enable access to the server/network resources through an encrypted and secured tunnel like OpenVPN and others. The "server" runs on Linux and the "clients" can run on any number of platforms (the WireGuard Project offers apps on both iOS and Android platforms in addition to Linux, Windows and MacOS). See the official project install link for more.
Server
On the peer that will act as the "server", first enable IPv4 forwarding using sysctl:
# sysctl -w net.ipv4.ip_forward=1
To make the change permanent, add net.ipv4.ip_forward = 1 to /etc/sysctl.d/99-sysctl.conf.
A properly configured firewall is HIGHLY recommended for any Internet-facing device.
If the server has a public IP configured, be sure to:
- Allow UDP traffic on the specified port(s) on which WireGuard will be running (for example allowing traffic on
51820/UDP). - Setup the forwarding policy for the firewall if it is not included in the WireGuard config for the interface itself
/etc/wireguard/wg0.conf. The example below should have the iptables rules and work as-is.
If the server is behind NAT, be sure to forward the specified port(s) on which WireGuard will be running (for example, 51820/UDP) from the router to the WireGuard server.
Key generation
Generate key pairs for the server and for each client as explained in #Key generation.
Server config
Create the "server" config file:
/etc/wireguard/wg0.conf
[Interface] Address = 10.200.200.1/24 ListenPort = 51820 PrivateKey = SERVER_PRIVATE_KEY # substitute eth0 in the following lines to match the Internet-facing interface # if the server is behind a router and receives traffic via NAT, these iptables rules are not needed PostUp = iptables -A FORWARD -i %i -j ACCEPT; iptables -A FORWARD -o %i -j ACCEPT; iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE PostDown = iptables -D FORWARD -i %i -j ACCEPT; iptables -D FORWARD -o %i -j ACCEPT; iptables -t nat -D POSTROUTING -o eth0 -j MASQUERADE [Peer] # foo PublicKey = PEER_FOO_PUBLIC_KEY PresharedKey = PRE-SHARED_KEY AllowedIPs = 10.200.200.2/32 [Peer] # bar PublicKey = PEER_BAR_PUBLIC_KEY PresharedKey = PRE-SHARED_KEY AllowedIPs = 10.200.200.3/32
Additional peers ("clients") can be listed in the same format as needed. Each peer requires the PublicKey to be set. However, specifying PresharedKey is optional.
Notice that the Address has a netmask of /24 and the clients on AllowedIPs /32. The clients only use their IP and the server only sends back their respective address.
The interface can be managed manually using wg-quick(8) or using a systemd service managed via systemctl(1).
The interface may be brought up using wg-quick up wg0 respectively by starting and potentially enabling the interface via wg-quick@interface.service, e.g. wg-quick@wg0.service. To close the interface use wg-quick down wg0 respectively stop wg-quick@interface.service.
Client config
Create the corresponding "client" config file(s):
foo.conf
[Interface] Address = 10.200.200.2/32 PrivateKey = PEER_FOO_PRIVATE_KEY DNS = 10.200.200.1 [Peer] PublicKey = SERVER_PUBLICKEY PresharedKey = PRE-SHARED_KEY Endpoint = my.ddns.example.com:51820 AllowedIPs = 0.0.0.0/0, ::/0
bar.conf
[Interface] Address = 10.200.200.3/32 PrivateKey = PEER_BAR_PRIVATE_KEY DNS = 10.200.200.1 [Peer] PublicKey = SERVER_PUBLICKEY PresharedKey = PRE-SHARED KEY Endpoint = my.ddns.example.com:51820 AllowedIPs = 0.0.0.0/0, ::/0
Using the catch-all AllowedIPs = 0.0.0.0/0, ::/0 will forward all IPv4 (0.0.0.0/0) and IPv6 (::/0) traffic over the VPN.
NetworkManager-wait-online.service and users of systemd-networkd may need to enable the systemd-networkd-wait-online.service to wait until devices are network-ready before attempting a WireGuard connection.Testing the tunnel
Once a tunnel has been established, one can use netcat to send traffic through it to test out throughput, CPU usage, etc.
On one side of the tunnel, run nc in listen mode and on the other side, pipe some data from /dev/zero into nc in sending mode.
In the example below, port 2222 is used for the traffic (be sure to allow traffic on port 2222 if using a firewall).
On one side of the tunnel listen for traffic:
$ nc -vvlnp 2222
On the other side of the tunnel, send some traffic:
$ dd if=/dev/zero bs=1024K count=1024 | nc -v 10.0.0.203 2222
Status can be monitored using wg directly.
# wg
interface: wg0 public key: UguPyBThx/+xMXeTbRYkKlP0Wh/QZT3vTLPOVaaXTD8= private key: (hidden) listening port: 51820 peer: 9jalV3EEBnVXahro0pRMQ+cHlmjE33Slo9tddzCVtCw= preshared key: (hidden) endpoint: 192.168.1.216:53207 allowed ips: 10.0.0.0/0 latest handshake: 1 minutes, 17 seconds ago transfer: 56.43 GiB received, 1.06 TiB sent
Tips and tricks
Store private keys in encrypted form
It may be desirable to store private keys in encrypted form, such as through use of pass. Just replace the PrivateKey line under [Interface] in the configuration file with:
PostUp = wg set %i private-key <(su user -c "export PASSWORD_STORE_DIR=/path/to/your/store/; pass WireGuard/private-keys/%i")
where user is the Linux username of interest. See the wg-quick(8) man page for more details.
Endpoint with changing IP
After resolving a server's domain, WireGuard will not check for changes in DNS again.
If the WireGuard server is frequently changing its IP-address due DHCP, Dyndns, IPv6, etc., any WireGuard client is going to lose its connection, until its endpoint is updated via something like wg set "$INTERFACE" peer "$PUBLIC_KEY" endpoint "$ENDPOINT".
Also be aware, if the endpoint is ever going to change its address (for example when moving to a new provider/datacenter), just updating DNS will not be enough, so periodically running reresolve-dns might make sense on any DNS-based setup.
Luckily, wireguard-tools provides an example script /usr/share/wireguard-tools/examples/reresolve-dns/reresolve-dns.sh, that parses WG configuration files and automatically resets the endpoint address.
One needs to run the /usr/share/wireguard-tools/examples/reresolve-dns/reresolve-dns.sh /etc/wireguard/wg.conf periodically to recover from an endpoint that has changed its IP.
One way of doing so is by updating all WireGuard endpoints once every thirty seconds[6] via a systemd timer:
/etc/systemd/system/wireguard_reresolve-dns.timer
[Unit] Description=Periodically reresolve DNS of all WireGuard endpoints [Timer] OnCalendar=*:*:0/30 [Install] WantedBy=timers.target
/etc/systemd/system/wireguard_reresolve-dns.service
[Unit] Description=Reresolve DNS of all WireGuard endpoints Wants=network-online.target After=network-online.target [Service] Type=oneshot ExecStart=/bin/sh -c 'for i in /etc/wireguard/*.conf; do /usr/share/wireguard-tools/examples/reresolve-dns/reresolve-dns.sh "$i"; done'
Afterwards enable and start wireguard_reresolve-dns.timer
Generate QR code
If the client is a mobile device such as a phone, qrencode can be used to generate client's configuration QR code and display it in terminal:
$ qrencode -t ansiutf8 -r client.conf
Enable debug logs
When using the Linux kernel module on a kernel that supports dynamic debugging, debugging information can be written into the kernel ring buffer (viewable with dmesg and journalctl) by running:
# modprobe wireguard # echo module wireguard +p > /sys/kernel/debug/dynamic_debug/control
Reload peer (server) configuration
In case the WireGuard peer (mostly server) adding or removing another peers from its configuration and wants to reload it without stopping any active sessions, one can execute the following command to do it:
# wg syncconf ${WGNET} <(wg-quick strip ${WGNET})
Where $WGNET is WireGuard interface name or configuration base name, for example wg0 (for server) or client (without the .conf extension, for client).
Troubleshooting
Routes are periodically reset
Users of NetworkManager should make sure that it is not managing the WireGuard interface(s). For example, create the following configuration file:
/etc/NetworkManager/conf.d/unmanaged.conf
[keyfile] unmanaged-devices=type:wireguard
Broken DNS resolution
When tunneling all traffic through a WireGuard interface, the connection can become seemingly lost after a while or upon new connection. This could be caused by a network manager or DHCP client overwriting /etc/resolv.conf.
By default wg-quick uses resolvconf to register new DNS entries (from the DNS keyword in the configuration file). This will cause issues with network managers and DHCP clients that do not use resolvconf, as they will overwrite /etc/resolv.conf thus removing the DNS servers added by wg-quick.
The solution is to use networking software that supports resolvconf.
Users of NetworkManager should know that it does not use resolvconf by default. It is recommended to use systemd-resolved. If this is undesirable, install openresolv and configure NetworkManager to use it: NetworkManager#Use openresolv.
Low MTU
Due to too low MTU (lower than 1280), wg-quick may have failed to create the WireGuard interface. This can be solved by setting the MTU value in WireGuard configuration in Interface section on client.
/foo.config
[Interface] Address = 10.200.200.2/24 MTU = 1420 PrivateKey = PEER_FOO_PRIVATE_KEY DNS = 10.200.200.1
Key is not the correct length or format
To avoid the following error, put the key value in the configuration file and not the path to the key file.
# wg-quick up wg0
[#] ip link add wg0 type wireguard [#] wg setconf wg0 /dev/fd/63 Key is not the correct length or format: `/path/example.key' Configuration parsing error [#] ip link delete dev wg0
Unable to establish a persistent connection behind NAT / firewall
By default, WireGuard peers remain silent while they do not need to communicate, so peers located behind a NAT and/or firewall may be unreachable from other peers until they reach out to other peers themselves (or the connection may time out). Adding PersistentKeepalive = 25 to the [Peer] settings of a peer located behind a NAT and/or firewall can ensure that the connection remains open.
# Set the persistent-keepalive via command line (temporarily)
[#] wg set wg0 peer $PUBKEY persistent-keepalive 25
Loop routing
Adding the endpoint IP to the allowed IPs list, the kernel will attempt to send handshakes to said device binding, rather than using the original route. This results in failed handshake attempts.
As a workaround, the correct route to the endpoint needs to be manually added using
ip route add <endpoint ip> via <gateway> dev <network interface>
e.g. for peer B from above in a standard LAN setup:
ip route add 203.0.113.102 via 192.168.0.1 dev eth0
To make this route persistent, the command can be added as PostUp = ip route ... to the [Interface] section of wg0.conf. However, on certain setups (e.g. using wg-quick@.service in combination with NetworkManager) this might fail on resume. Furthermore, this only works for a static network setup and fails if gateways or devices change (e.g. using ethernet or wifi on a laptop).
Using NetworkManager, a more flexible solution is to start WireGuard using a dispatcher script. As root, create
/etc/NetworkManager/dispatcher.d/50-wg0.sh
#!/bin/sh case $2 in up) wg-quick up wg0 ip route add <endpoint ip> via $IP4_GATEWAY dev $DEVICE_IP_IFACE ;; pre-down) wg-quick down wg0 ;; esac
If not already running, start and enable NetworkManager-dispatcher.service.
Also, make sure that NetworkManager is not managing routes for wg0 (see above).