WireGuard - ArchWiki

Jump to content

# WireGuard

From ArchWiki

Related articles

- Linux Containers/Using VPNs
- Rosenpass

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 has been included in the Linux kernel since late 2019.

## 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

- wireguird — A linux GTK GUI client for WireGuard.

  https://github.com/UnnoTed/wireguird || wireguirdAUR

- wireguard-gui — A wireguard client GUI for Linux made with nextauri.

  https://github.com/0xle0ne/wireguard-gui || wireguard-gui-binAUR

### Command-line tools

- wg_tool — Tool to manage wireguard configs for server and users.

  https://github.com/gene-git/wg_tool || wg_toolAUR

- wg-client — Linux client with both command line and GUI.

  https://github.com/gene-git/wg-client || wg-clientAUR

- wg2nd — A tool to convert WireGuard configurations from wg-quick(8) format into systemd-networkd compatible configurations.

  https://git.flu0r1ne.net/wg2nd/about || wg2ndAUR

## Basic configuration

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

Tip The same UDP port can be used for all peers.

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)

Note It is recommended to only allow reading and writing access for the owner. The above alters the umask temporarily within a sub-shell to ensure that access (read/write permissions) is restricted to the owner.

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 (make sure to use `umask 0077` for this as well):

    $ 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-address, or alternatively wicuvanityAUR, do this.

For example:

    $ wireguard-vanity-address --in 8 leslie

    searching for 'leslie' in pubkey[0..10], one of every 214748364 keys should match
    one core runs at 2.69e6 keys/s, CPU cores available: 16
    est yield: 5.0 seconds per key, 200.10e-3 keys/s
    hit Ctrl-C to stop
    private wEoVMj92P+E3fQXVf9IixWJqpCqcnP/4OfvrB1g3zmY=  public LEsliEny+aMcWcRbh8Qf414XsQHSBOAFk3TaEk/aSD0=
    private EAOwlGGqpHVbZ9ehaCspdBJt+lkMcCfkwiA5T5a4JFs=  public VlesLiEB5BFd//OD2ILKXviolfz+hodG6uZ+XjoalC8=
    private UDWG4VWI+RzAGzNSnlC+0X4d3nk9goWPs/NRC5tX524=  public 9lESlieIFOlJFV6dG7Omao2WS+amWgshDdBYn8ahRjo=

### Peer setup

Manual setup is accomplished by using ip(8) and wg(8).

Note These examples use the pre-shared keys which were introduced as optional in #Key generation. If not using them, simply ignore the corresponding parts in the commands.

Peer A setup:

In this example, peer A will listen on UDP port 51871 and will accept connection from peers 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

Tip To cleanly tear down the connection as well as deleting the interface, run

    # ip link delete dev wg0

everywhere the previous commands were used.

### 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

## Additional routes

To establish connections more complicated than point-to-point, additional setup is necessary.

This article or section needs expansion.

Reason: Add a scenario: only peer A has a public IP address (i.e. endpoint), peers B and C (which are generally behind a NAT) connect to peer A with `PersistentKeepalive`, connections from peer B to peer C and vice versa are routed via peer A. Configuration: peers B and C have `10.0.0.0/24` in `AllowedIPs` for peer A, peer A must enable packet forwarding and masquerading via firewall rules, e.g. `iptables -A FORWARD -i wg+ -j ACCEPT` and `iptables -t nat -A POSTROUTING -s 10.0.0.0/24 -o wg0 -j MASQUERADE`. (Discuss in Talk:WireGuard)

### 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

This article or section needs expansion.

Reason: Add `ip route` examples; add alternative using NAT; mention the situation when the site-peer is the network's gateway. (Discuss in Talk:WireGuard)

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.

Tip Deploy routes network-wide by configuring them in the router. E.g., using DHCP option 121.

After that, enable IP forwarding on the peer through which other devices on the network will connect to WireGuard peer(s).

### 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

To route everything over the WireGuard tunnel, use:

    # ip route add default dev wg0 table 2468
    # wg set wg0 fwmark 1234
    # ip rule add not fwmark 1234 table 2468 pref 10

In the first line, the default route is added to an alternative routing table (table 2468). The only purpose of this alternative routing table is to hand packets over to the wg0 interface.

In the second line, all outgoing packets handled by the wg0 interface are marked with a firewall mark.

In the third line, packets lacking this firewall mark are directed to the alternative routing table 2468, which routes them to the wg0 interface. `pref 10` indicates that this rule has priority 10. To list all rules with their corresponding priority, use `ip rule show`. These rules determine which routing table will be employed for a certain packets.

This implementation's main strength lies in its avoidance of using any endpoint. This is advantageous because WireGuard endpoints can roam. It is possible to define WireGuard peers without an endpoint.

The local access network will be inaccessible in this implementation. To whitelist LAN use:

    # ip rule add suppress_prefixlength 0 table main pref 5

It's fairly straightforward to add things to the whitelist using ip-rule(8). For instance, to give a certain user permission to send queries outside the WireGuard tunnel, use:

    # ip rule add uidrange 955-955 table main pref 5

955 is the user ID of the user. The user IDs of all users can be found in `/etc/passwd`.

## 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

Note If a peer will act as a DNS server, make sure to use its WireGuard tunnel address(es) as the DNS server address(es) instead of another of its addresses from allowed IPs. Otherwise DNS lookups may fail.

## 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[1], NetworkManager and ConnMan[2].

Note

- netctl relies on wg(8) from wireguard-tools and `/etc/wireguard/interfacename.conf` configuration files for establishing WireGuard connections.
- ConnMan has a very limited support for WireGuard. It can connect to only one peer.[3]

### 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.

Note

- 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

    [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 (`0.0.0.0/0` for IPv4 and `::/0` for IPv6) to `AllowedIPs`. E.g. `AllowedIPs = 0.0.0.0/0, ::/0`. wg-quick will automatically take care of setting up correct routing and fwmark[4] so that networking still functions.
- To use a peer as a DNS server, set `DNS = wireguard_internal_ip_address_of_peer` in the `[Interface]` section. Search domains are also set with the `DNS =` 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

    [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

    [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.

Note Routing all DNS over WireGuard (i.e. `Domains=~.`) will prevent the DNS resolution of endpoints. Unless the peer domain is configured to be resolved on a specific network link.

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
    RouteTable=main

    [WireGuardPeer]
    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

    [WireGuardPeer]
    PublicKey=PEER_C_PUBLIC_KEY
    PresharedKey=PEER_A-PEER_C-PRESHARED_KEY
    AllowedIPs=10.0.0.3/32,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 the `Domains=` option. See systemd.network(5) § [NETWORK] SECTION OPTIONS for details.
- To use a peer as the only DNS server set `DNSDefaultRoute=true` and `Domains=~.` in the `[Network]` section of .network file's.
- To automatically create routes for everything in `AllowedIPs`, add `RouteTable=main` to the `[WireGuard]` or `[WireGuardPeer]` sections in the .netdev file. Alternatively, additional routes can be specified manually using `[Route]` sections in the .network file.

Warning In order to prevent the leaking of private and preshared keys, it is recommended to set the permissions of the .netdev file:

    # chown root:systemd-network /etc/systemd/network/99-wg*.netdev
    # chmod 0640 /etc/systemd/network/99-wg*.netdev

Alternatively, the keys can be stored in separate files and referenced with `PrivateKeyFile=`, `PresharedKeyFile=` and `PublicKeyFile=`, or they can be stored encrypted using systemd-creds. See #Using systemd credentials for private keys (systemd-networkd).

Tip To use the WireGuard interface name or IP addresses in nftables rules via systemd-networkd's NFTSet option, specify the addresses in `[Address]` sections instead of the `[Network]` section. E.g.:

    /etc/systemd/network/99-wg0.network

    ...
    [Address]
    Address=10.0.0.1/24
    NFTSet=address:inet:my_table:wg_ipv4_address
    NFTSet=prefix:inet:my_table:wg_ipv4_prefix
    NFTSet=ifindex:inet:my_table:wg_ifindex

    [Address]
    Address=fdc9:281f:04d7:9ee9::1/64
    NFTSet=address:inet:my_table:wg_ipv6_address
    NFTSet=prefix:inet:my_table:wg_ipv6_prefix
    NFTSet=ifindex:inet:my_table:wg_ifindex

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
    RouteTable=main

    [WireGuardPeer]
    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

    [WireGuardPeer]
    PublicKey=PEER_C_PUBLIC_KEY
    PresharedKey=PEER_B-PEER_C-PRESHARED_KEY
    AllowedIPs=10.0.0.3/32,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
    RouteTable=main

    [WireGuardPeer]
    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

    [WireGuardPeer]
    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

    /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 a public IP address. Peer B routes all its traffic over the 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
    RouteTable=main

    [WireGuardPeer]
    PublicKey=PEER_B_PUBLIC_KEY
    PresharedKey=PEER_A-PEER_B-PRESHARED_KEY
    AllowedIPs=10.0.0.2/32,fd31::2/128

    /etc/systemd/network/99-wg0.network

    [Match]
    Name=wg0

    [Network]
    Address=10.0.0.1/32
    Address=fd31::1/128
    IPMasquerade=both

Note The `IPMasquerade=both` option enables IP forwarding on the WireGuard interface for both IPv4 and v6, sets up firewall rules for IP masquerading for it in order for Peer A to provide working internet to Peer B. Additionally:

- Enable IP forwarding for the interface that is used for connecting to the Internet (i.e. add `IPv4Forwarding=yes` to its .network file).
- Make sure that the firewall does not block forwarding.
- Configure the local DNS server to accept connections to the WireGuard interface IP address. For systemd-resolved see systemd-resolved#Additional listening interfaces.
- To automatically create routes for everything in `AllowedIPs`, add `RouteTable=main` to the `[WireGuard]` or `[WireGuardPeer]` sections in the .netdev file.

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,::/0
    # Endpoint=[2a01::1]:51871
    Endpoint=198.51.100.101:51871
    RouteTable=1000

In the netdev configuration, the most interesting lines are `RouteTable=1000` and `FirewallMark=0x8888`. The `RouteTable` line specifies that a new routing table with id `1000` is created for the WireGuard interface, and no rules are set on the main routing table.

The `FirewallMark` simply marks all packets send and received by this WireGuard interface with the number `0x8888`, which can be used to define policy rules on these packets.

    /etc/systemd/network/50-wg0.network

    [Match]
    Name=wg0

    [Network]
    Address=10.0.0.2/32
    Address=fd31::2/128
    DNS=10.0.0.1
    DNS=fd31::1
    DNSDefaultRoute=true
    Domains=~.

    [RoutingPolicyRule]
    Family=both
    FirewallMark=0x8888
    InvertRule=true
    Table=1000
    Priority=10

    # Exempt the endpoint IP address so that wireguard can still connect to it.
    [RoutingPolicyRule]
    To=198.51.100.101/32
    Priority=5

    [RoutingPolicyRule]
    To=2a01::1/128
    Priority=5

We define two routing policies here. For all packets not marked with `0x8888` (i.e. all non-WireGuard/regulal traffic), we specify that the routing table `1000` must be used (which is the WireGuard routing table). This rule routes all traffic through WireGuard.

We exempt our endpoint with a higher priority by routing it through the main table (`Table=main` is default).

Exempting specific addresses

In order to exempt specific addresses (such as private LAN addresses) from routing over the WireGuard tunnel, add them to another `RoutingPolicyRule` with a higher priority.

    /etc/systemd/network/50-wg0.network

    ...
    [RoutingPolicyRule]
    To=192.168.0.0/24
    Priority=9
    ...

Route for specific user

It may be desirable to route WAN traffic over the tunnel only for a specific user, for example, the transmission user in order to use the tunnel for torrent traffic.

    /etc/systemd/network/99-wg0.network

    ...
    [RoutingPolicyRule]
    Table=1000
    User=transmission
    Priority=30001
    Family=both

    [RoutingPolicyRule]
    Table=main
    User=transmission
    SuppressPrefixLength=0
    Priority=30000
    Family=both
    ...

The higher priority rule (`30000`), matches all traffic generated by the transmission user and routes it through the main table (no WireGuard) but only using rules with a prefix length larger than `0`. This excludes the default catch-all rule. Therefore, only traffic matching specific rules (such as those defining the subnet of your local home network) of the main table are routed through the main table.

The lower priority rule (`30001`), matches all traffic generated by the transmission user and routes it through table `1000` which is the WireGuard table.

Note These rules are to be put instead of the two rules defined at the start of this section to route all traffic through WireGuard.

Testing

Test the proxy with

    # ipv4
    $ curl -4 zx2c4.com/ip

    # ipv6
    $ curl -6 zx2c4.com/ip

Check systemd-networkd log for any error and warning messages.

    $ journalctl -u systemd-networkd.service

Invoke the `wg` command from wireguard-tools.

### 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 the wg0 interface on every participating peer as needed, i.e.

    # 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 configuration file and add this network to `AllowedIPs` in the WireGuard profile, e.g. `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.

Tip NetworkManager can import a wg-quick configuration file. E.g.:

    # nmcli connection import type wireguard file /etc/wireguard/wg0.conf

#### NMConnection file

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 (`0.0.0.0/0` for IPv4 and `::/0` for IPv6) to `wireguard-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.dns` and `ipv6.dns` settings. Search domains can be specified with the `ipv4.dns-search=` and `ipv6.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

#### nmcli

From NetworkManager 1.56, nmcli(1) has trivial support for editing Wireguard peer details instead of needing to edit the `.nmconnection` files directly on disk in order to fully configure a Wireguard connection. However, the syntax for these operations is much the same as writing a `.nmconnection` file directly; see above for further details.

Examples:

Add a single peer with two AllowedIP entries. Note that the list of IP addresses doesn't end with the `;` separator, but it will be appended when written to the `.nmconnection` file on disk.

    # nmcli c modify NM_WIREGUARD_CONNECTION_ID wireguard.peers "PEER_PUBLIC_KEY allowed-ips=3fff:1:4:9::/64;3fff::2112/128"

Add multiple peers, each with a single AllowedIP, one with a preshared-key and an endpoint, and the other with a persistent-keepalive. Note how the peers are split by a `,` not a `;` as with the allowed IPs.

    # nmcli c modify NM_WIREGUARD_CONNECTION_ID wireguard.peers "PEER_A_PUBLIC_KEY allowed-ips=192.0.2.0/24 endpoint=wg.example.com preshared-key=PEER_A_PRESHARED_KEY,PEER_B_PUBLIC_KEY allowed-ips=192.0.2.12/32 persistent-keepalive=25"

## Specific use-case: VPN server

This article or section is a candidate for merging with #wg-quick.

Notes: Same use case. (Discuss in Talk:WireGuard)
Note Usage of the terms "server" and "client" were purposefully chosen in this section specifically to help new users/existing OpenVPN users become familiar with the construction of WireGuard's configuration files. WireGuard documentation simply refers to both of these concepts as "peers."

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.

Tip Instead of using wireguard-tools for server/client configuration, one may also use systemd-networkd native WireGuard support.

### Server

This article or section is a candidate for merging with #Site-to-point.

Notes: Same use case. (Discuss in Talk:WireGuard)

On the peer that will act as the "server", first enable IPv4 forwarding.

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 configuration 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 configuration

Create the "server" configuration 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
    # the FORWARD rules will always be needed since traffic needs to be forwarded between the WireGuard
    # interface and the other interfaces on the server.
    # if the server is behind a router and receives traffic via NAT, specify static routing back to the
    # 10.200.200.0/24 subnet, the NAT iptables rules are not needed but the FORWARD rules are needed.
    # if the server is behind a router and receives traffic via NAT but one cannot specify static routing back to
    # 10.200.200.0/24 subnet, both the NAT and FORWARD iptables rules are 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 addresses.

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 configuration

Create the corresponding "client" configuration 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.

Note Users of NetworkManager, may need to enable the `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

This article or section is a candidate for merging with #Basic checkups.

Notes: Same topic. (Discuss in Talk:WireGuard)

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 (wg-quick)

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 WireGuard 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.

Alternatively, systemd-creds can be used. This can be helpful to create encrypted private keys that are bound to the system's TPM. See systemd-creds(1) for more details.

First, create an encrypted credential:

    # echo -n your_wg_private_key | systemd-creds --tpm2-device=auto encrypt - /etc/credstore.encrypted/wg-private-key.cred

Finally, replace the `PrivateKey` line under `[Interface]` in the WireGuard configuration file with:

    PostUp = wg set %i private-key <(systemd-creds decrypt /etc/credstore.encrypted/wg-private-key.cred)

### Using systemd credentials for private keys (systemd-networkd)

You can use systemd-creds to store your private keys encrypted.

    # echo -n your_wg_private_key | systemd-creds encrypt - /etc/credstore.encrypted/network.wireguard.private.wg0
    # echo -n your_pre_shared_key | systemd-creds encrypt - /etc/credstore.encrypted/network.wireguard.psk.wg0

Note The name of the store must match `network.wireguard.*`. See systemd.netdev(5) § [WIREGUARD]_SECTION_OPTIONS.

Modify your .netdev file to use

    PrivateKey = @network.wireguard.private.wg0
    PresharedKey = @network.wireguard.psk.wg0

### 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[5] 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 nss-lookup.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 debug, 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).

Users of `wg-quick@.service` can simply reload the service.

This article or section needs expansion.

Reason: Show how to do this with other network managers from #Persistent configuration. (Discuss in Talk:WireGuard)

### Workaround for some public Wi-Fi networks seemingly blocking WireGuard connections

Note This workaround will only be an option if a cellular connection is available on the device.

Some Wi-Fi networks can be configured to actively identify and block WireGuard's handshake thus preventing the initial connection and preventing the establishment of the secure tunnel.

This strategy works for blocking new WireGuard connections but it is useless against existing connections. Therefore, to use WireGuard on such a network, simply connect to the WireGuard peer over cellular before joining the Wi-Fi network thus allowing the handshake to take place before the active blocking can occur. WireGuard will keep this tunnel open as the devices transitions from cellular to Wi-Fi.

## 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.

Note Users of systemd-resolved should make sure that systemd-resolvconf is installed.

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.

### Adjusting the MTU value

A default Wireguard maximum transmission unit (MTU) value is `1420`.

Due to a 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

Depending on your network, a lower MTU value can also make your WireGuard connection work.

In certain cases larger MTU values can lead to unstable or intermittent connection because of unreliable Path MTU discovery (PMTU) along the route. Which may lead to situations where ICMP ping works because of its low packet size, but most of TCP connections fail because of full MTU size utilization. For example, an IPv6 connection has a higher packet overhead than IPv4, hence fragmentation may occur earlier with the same MTU value.

It is worth checking the links MTU size on both peers and other routers involved to determine the minimum value.

    # ip link show

    5: wg0: <POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1400 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
    link/none

Another option is falling back to a MTU of `1280` and finding appropriate value for given path with a trial/error approach.

An MTU of `1420` and above can lead to partially broken links which could be interpreted as a firewall or routing issue instead of actual MTU size.

### 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.

To temporarily set the persistent-keepalive setting via command line, run the following command:

    # wg set wg0 peer public_key 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 Wi-Fi 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 #Routes are periodically reset.

### Connection lost after sleep using systemd-networkd

systemd version 253 introduced a change in how network interfaces are reconfigured when resuming from a suspended state[6]. In doing so, network connections managed by systemd-networkd will lose connection to the WireGuard interface. Unless a kill switch is configured, this risks exposing the public IP address after resuming from suspension. To fix this, uncomment and change the value to `no` for `ManageForeignRoutingPolicyRules` in `/etc/systemd/networkd.conf`.[7] If your WireGuard interface uses the `fwmark` setting, you may also need to set `ManageForeignRoutes` to `no`.

Review the systemd-networkd page in full to become informed of any other potential side effects of this change.

## See also

- Wikipedia:WireGuard
- Presentations by Jason Donenfeld.
- Mailing list
- Unofficial WireGuard Documentation
- Debian:Wireguard
- Pro Custodibus Documentation on additional routing setups and topologies.

Category:

- Virtual Private Network

Hidden categories:

- Pages or sections flagged with Template:Expansion
- Pages or sections flagged with Template:Merge

WireGuard
Add topic