WireGuard

From ArchWiki
Jump to: navigation, search

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 plans to be cross-platform and widely deployable. It is currently under heavy development, but already it might be regarded as the most secure, easiest to use, and simplest VPN solution in the industry.
Warning: WireGuard has not undergone proper degrees of security auditing and the protocol is still subject to change.[1]

Installation

Install the wireguard-tools package.

Usage

To create a public and private key on a peer:

$ wg genkey | tee privatekey | wg pubkey > publickey

Below commands will demonstrate how to setup a basic tunnel between two peers with the following settings:

Peer A Peer B
External IP address 10.10.10.1/24 10.10.10.2/24
Internal IP address 10.0.0.1/24 10.0.0.2/24
wireguard listening port UDP/48574 UDP/39814

The external addresses should already exist. For example, peer A should be able to ping peer B via ping 10.10.10.2, and vice versa. The internal addresses will be new addresses created by the ip commands below and will be shared internally within the new WireGuard network. The /24 in the IP addresses is the CIDR.

Peer A setup

This peer will listen on UDP port 48574 and will accept connection from peer B by linking its public key with both its inner and outer IPs addresses.

# ip link add dev wg0 type wireguard
# ip addr add 10.0.0.1/24 dev wg0
# wg set wg0 listen-port 48574 private-key ./privatekey
# wg set wg0 peer [Peer B public key] persistent-keepalive 25 allowed-ips 10.0.0.2/32 endpoint 10.10.10.2:39814
# ip link set wg0 up

[Peer B public key] should have the same format as EsnHH9m6RthHSs+sd9uM6eCHe/mMVFaRh93GYadDDnM=. allowed-ips is a list of addresses that peer A will be able to send traffic to. allowed-ips 0.0.0.0/0 would allow sending traffic to any address.

Peer B setup

As with Peer A, whereas the wireguard daemon is listening on the UDP port 39814 and accept connection from peer A only.

# ip link add dev wg0 type wireguard
# ip addr add 10.0.0.2/24 dev wg0
# wg set wg0 listen-port 39814 private-key ./privatekey
# wg set wg0 peer [Peer A public key] persistent-keepalive 25 allowed-ips 10.0.0.1/32 endpoint 10.10.10.1:48574
# ip link set wg0 up

Basic checkups

Invoking the wg command without parameter 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:

 peer-a$ wg
 interface: wg0
   public key: UguPyBThx/+xMXeTbRYkKlP0Wh/QZT3vTLPOVaaXTD8=
   private key: (hidden)
   listening port: 48574
 
 peer: 9jalV3EEBnVXahro0pRMQ+cHlmjE33Slo9tddzCVtCw=
   endpoint: 10.10.10.2:39814
   allowed ips: 10.0.0.2/32

At this point one could reach the end of the tunnel:

 peer-a$ ping 10.0.0.2

Persistent configuration

The config can be saved by utilizing showconf

# wg showconf wg0 > /etc/wireguard/wg0.conf
# wg setconf wg0 /etc/wireguard/wg0.conf

Example peer configuration

/etc/wireguard/wg0.conf
[Interface]
PrivateKey = [CLIENT PRIVATE KEY]

[Peer]
PublicKey = [SERVER PUBLICKEY]
AllowedIPs = 10.0.0.0/24, 10.123.45.0/24, 1234:4567:89ab::/48
Endpoint = [SERVER ENDPOINT]:51820
PersistentKeepalive = 25

Setup a VPN server

Wireguard comes with a tool to quickly create and tear down VPN servers and clients, wg-quick. Note that the config file used here is not a valid config file that can be used with wg setconf, and that you'll possibly have to change at least the interface from eth0 to the one you use.

Server

/etc/wireguard/wg0server.conf
[Interface]
Address = 10.0.0.1/24  # This is the virtual IP address, with the subnet mask we will use for the VPN
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
ListenPort = 51820
PrivateKey = [SERVER PRIVATE KEY]

[Peer]
PublicKey = [CLIENT PUBLIC KEY]
AllowedIPs = 10.0.0.2/32  # This denotes the clients IP with a /32: the client only has ONE IP.

In order for the iptables rules to work, IPv4 forwarding should be enabled:

# sysctl net.ipv4.ip_forward=1

To make the change permanent, add net.ipv4.ip_forward = 1 to /etc/sysctl.d/99-sysctl.conf.

Bring the interface up by using wg-quick up wg0server, and use wg-quick down wg0server to bring it down.

Client (tunnel all traffic)

/etc/wireguard/wg0.conf
[Interface]
Address = 10.0.0.2/24  # The client IP from wg0server.conf with the same subnet mask
PrivateKey = [CLIENT PRIVATE KEY]
DNS = 10.0.0.1

[Peer]
PublicKey = [SERVER PUBLICKEY]
AllowedIPs = 0.0.0.0/0, ::0/0
Endpoint = [SERVER ENDPOINT]:51820
PersistentKeepalive = 25

Bring this interface up by using wg-quick up wg0, and use wg-quick down wg0 to bring it down.

To bring this up automatically one can use systemctl enable wg-quick@wg0

If you use NetworkManager, it may be necessary to also enable NetworkManager-wait-online.service systemctl enable NetworkManager-wait-online.service

or if you're using systemd-networkd, to enable systemd-networkd-wait-online.service systemctl enable systemd-networkd-wait-online.service

to wait until devices are network ready before attempting wireguard connection.

Troubleshooting

DKMS module not available

If the following command does not list any module after you installed wireguard-dkms,

$ modprobe wireguard && lsmod | grep wireguard

or if creating a new link returns

# ip link add dev wg0 type wireguard
RTNETLINK answers: Operation not supported

you probably miss the linux headers.

These headers are available in linux-headers or linux-lts-headers depending of the kernel installed on your system.

Routes are periodically reset

Make sure that NetworkManager is not managing your Wireguard interface:

/etc/NetworkManager/conf.d/unmanaged.conf
[keyfile]
unmanaged-devices=interface-name:wg0

Connection loss with NetworkManager

On desktop, connection loss can be experienced when all the traffic is tunnelled through a Wireguard interface: typically, the connection is seemingly lost after a while or upon new connection to an access point.

By default wg-quick uses a resolvconf provider such as openresolv to register new DNS entries (i.e. DNS keyword in the configuration file). However NetworkManager does not use resolvconf by default: every time a new DHCP lease is acquired, NetworkManager overwrites the global DNS addresses with the DHCP-provided ones which might not be available through the tunnel.

Using resolvconf

If resolvconf is already used by the system and you still experience connection loss, make sure NetworkManager is configured to use it: NetworkManager#Use_openresolv.

Using dnsmasq

See Dnsmasq#openresolv for configuration.

Using systemd-resolved

At the time of writing (Sept. 2018), the resolvconf-compatible mode offered by systemd-resolvconf does not work with wg-quick. However systemd-resolved can still be used by wg-quick through the PostUp hook. First make sure that NetworkManager is configured with systemd-resolved: NetworkManager#systemd-resolved and then alter the tunnel configuration:

/etc/wireguard/wg0.conf
[Interface]
Address = 10.0.0.2/24  # The client IP from wg0server.conf with the same subnet mask
PrivateKey = [CLIENT PRIVATE KEY]
PostUp = resolvectl domain %i "~."; resolvectl dns %i 10.0.0.1; resolvectl dnssec %i yes

[Peer]
PublicKey = [SERVER PUBLICKEY]
AllowedIPs = 0.0.0.0/0, ::0/0
Endpoint = [SERVER ENDPOINT]:51820
PersistentKeepalive = 25

Setting "~." as a domain name is necessary for systemd-resolved to give priority to the newly available DNS server.

No PostDown key is necessary as systemd-resolved automatically revert all parameters when wg0 is torn down.

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 your config 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 your username. See the wg-quick(8) man page for more details.