<i>All credit goes to the WireGuard project, [zx2c4](https://www.zx2c4.com/), [Edge Security](https://www.edgesecurity.com/), and the [open source contributors](https://github.com/WireGuard/WireGuard/graphs/contributors) for the original software,<br/> this is my solo unofficial attempt at providing more comprehensive documentation, API references, and examples.</i>
[WireGuard](https://www.wireguard.com/) is a BETA/WIP open-source VPN solution written in C by [Jason Donenfeld](https://www.jasondonenfeld.com) and [others](https://github.com/WireGuard/WireGuard/graphs/contributors), aiming to fix many of the problems that have plagued other modern server-to-server VPN offerings like IPSec/IKEv2, OpenVPN, or L2TP. It shares some similarities with other modern VPN offerings like [Tinc](https://www.tinc-vpn.org/) and [MeshBird](https://github.com/meshbird/meshbird), namely good cipher suites and minimal config.
This is my attempt at writing "The Missing Wireguard Documentation" to make up for the somewhat sparse offical docs on an otherwise great piece of software.
Over the last 8+ years I've tried a wide range of VPN solutions. Somewhat out of necessity, since the city I was living in was behind the Great Wall of China. Everything from old-school PPTP to crazy round-robin GoAgent AppEngine proxy setups were common back in the early 2010's to break through the GFW, these days it's mostly OpenVPN, StealthVPN, IPSec/IKEv2 and others. From the recommendation of a few people in the [RC](https://recurse.com) Zulip community, I decided to try WireGuard and was surprised to find it checked almost all the boxes.
- minimal config, low config surface area and few exposed tunables
- minimal key management overhead, 1 or 2 preshared keys or certs is ok, but ideally not both
- ability to easily create a LAN like 10.0.0.0/24 between all my servers, every peer can connect to every peer,
- ability to bust through NATs with a signalling server, routing nat-to-nat instead of through a relay (webrtc style)
- fallback to relay server when nat-to-nat busting is unavailable or unreliable
- ability to route to a fixed list of ips/hosts with 1 keypair per host (not needed, but nice to have: ability to route arbitrary local traffic or *all* internet traffic to a given host)
- encrypted, and secure by default (not needed, nice to have: short copy-pastable key pairs)
- ideally support for any type of Level 2 and control traffic, e.g. ARP/DHCP/ICMP (or ideally raw ethernet frames), not just TCP/HTTP
- ability to join the VPN from Ubuntu, FreeBSD, iOS, macOS (Windows/Android not needed but would be nice
- not a requirement, but ideally it would support running in docker with a single container, config file, and preshared key on each server, but with a full network interface exposed to the host system (maybe with tun/tap on the host passing traffic to the container, but ideally just a single container + config file without outside dependencies)
- [IPSec (IKEv2)](https://github.com/jawj/IKEv2-setup)/strongSwan: lots of brittle config that's different for each OS, NAT busting setup is very manual and involves updating the central server and starting all the others in the correct order, not great at reconnecting after network downtime, had to be manually restarted often
- [TINC](https://www.tinc-vpn.org/): haven't tried it yet, but it doesn't work on iOS, worst case senario I could live with that if it's the only option
- [OpenVPN](https://openvpn.net/vpn-server-resources/site-to-site-routing-explained-in-detail/): I don't like it from past experience but could be convinced if it's the only option
A host that connects to the VPN and has registers a VPN subnet address like 10.0.0.3 for itself. It can also optionally route traffic for more than its own address(es) by specifing subnet ranges in comma-separated CIDR notation.
A publicly reachable peer/node that serves as a fallback to relay traffic for other VPN peers behind NATs. A bounce server is not a special type of server, it's a normal peer just like all the others, the only difference is that it has a public IP and has kernel-level IP forwarding turned on which allows it to bounce traffic back down the VPN to other clients.
A group of IPs separate from the public internet, e.g. 10.0.0.1-255 or 192.168.1.1/24. Generally behind a NAT provided by a router, e.g. in office internet LAN or a home WiFi network.
A way of defining a subnet and its size with a "mask", a smaller mask = more address bits usable by the subnet & more IPs in the range. Most common ones:
To people just getting started `10.0.0.1/32` may seem like a weird and confusing way to refer to a single IP. This design is nice though because it allows peers to expose multiple IPs if needed without needing multiple notations. Just know that anywhere you see something like `10.0.0.3/32`, it really just means `10.0.0.3`.
A subnet with private IPs provided by a router standing in front of them doing Network Address Translation, individual nodes are not publicly accessible from the internet, instead the router keeps track of outgoing connections and forwards responses to the correct internal ip (e.g. standard office networks, home wifi networks, free public wifi networks, etc)
### Public Endpoint
The publicly accessible address:port for a node, e.g. `123.124.125.126:1234` or `some.domain.tld:1234` (must be accessible via the public internet, generally can't be a private ip like `10.0.0.1` or `192.168.1.1` unless it's directly accessible using that address by other peers on the same subnet).
### Private key
A wireguard private key for a single node, generated with:
A wireguard public key for a single node, generated with:
`wg pubkey < example.key > example.key.pub `
(shared with other peers)
### DNS
Domain Name Server, used to resolve hostnames to IPs for VPN clients, instead of allowing DNS requests to leak outside the VPN and reveal traffic. Leaks are testable with http://dnsleak.com.
Public relays are just normal VPN peers that are able to act as an intermediate relay server between any VPN clients behind NATs, they can forward any VPN subnet traffic they receives to the correct peer at the system level (WireGuard doesn't care how this happens, it's handled by the kernel `net.ipv4.ip_forward = 1` and the iptables routing rules).
If all peers are publicly accessible, you don't have to worry about special treatment to make one of them a relay server, it's only needed if you have any peers connecting from behind a NAT.
Each client only needs to define the publicly accessible servers/peers in it's config, any traffic bound to other peers behind NATs will go to the catchall VPN subnet (e.g. `10.0.0.1/24`) in the public relays `AllowedIPs` route and will be forwarded accordingly once it hits the relay server.
In summary: only direct connections between clients should be configured, any connections that need to be bounced should not be defined as peers, as they should head to the bounce server first and be routed from there back down the vpn to the correct client.
### How WireGuard Routes Packets
More complex topologies are definitely achievable, but these are the basic routing methods used in typical WireGuard setups:
- **Direct node-to-node**
In the best case, the nodes are on the same LAN or are both publicly accessible, and traffic will route over encrypted UDP packets sent directly between the nodes.
- **Node behind local NAT to public node**
When 1 of the 2 parties is behind a remote NAT (e.g. when laptop behind a NAT connects to `public-server2`), the connection will be opened from NAT -> public client, then traffic will route directly between them in both directions as long as the connection is kept alive.
- **Node behind local NAT to node behind remote NAT (via relay)**
In the worst case when both parties are behind remote NATs, both will open a connection to `public-server1`, and traffic will forward through the intermediary bounce server as long as the connections are kept alive.
- **Node behind local NAT to node behind remote NAT (via NAT-busting)**
I'm not sure if Wireguard supports this method yet, but it's definitely possible in theory, see: [WebRTC](https://developer.mozilla.org/en-US/docs/Web/API/WebRTC_API), [N2N](https://www.ntop.org/products/n2n/), [Pwnat](https://samy.pl/pwnat/). A readily available signaling server like`public-server1` should make connection establishment and handoff relatively easy, but ICMP packet trickery can also be used. Please let me know if WireGuard does this via [Github Issue](https://github.com/pirate/wireguard-docs/issues).
Chosing the proper routing method is handled automatically by WireGuard as long as at least one server is acting as a public relay with `net.ipv4.ip_forward = 1` enabled, and clients have `AllowIPs = 10.0.0.1/24` set in the relay server `[peer]` (to take traffic for the whole subnet).
More specific (also usually more direct) routes provided by other peers will take precedence when available, otherwise traffic will fall back to the least specific route and use the `10.0.0.1/24` catchall to forward traffic to the bounce server, where it will in turn be routed by the relay server's system routing table back down the VPN to the specific peer thats accepting routes for that traffic.
You can figure out which routing method WireGuard is using for a given address by measuring the ping times to figure out the unique length of each hop, and by inspecting the output of:
```bash
wg show wg0
```
### What WireGuard Traffic Looks Like
WireGuard uses encrypted UDP packets for all traffic, it does not provice guarantees around packet delivery or ordering, as that is handled by TCP connections within the encrypted tunnel.
WireGuard claims faster performance than most other competing VPN solutions, though the exact numbers are sometimes debated and may depend on whether hardware-level acceleration is available for certain cryptographic ciphers.
WireGuard's performance gains are achieved by handling routing at the kernel level, and by using modern cipher suites running on all cores to encrypt traffic. WireGuard also gains a significant advantage by using UDP with no delivery/ordering guarantees (compared to VPNs that run over TCP or implement their own guaranteed delivery mechanisms).
WireGuard uses the following protocols and primitives to secure traffic:
- ChaCha20 for symmetric encryption, authenticated with Poly1305, using RFC7539’s AEAD construction
- Curve25519 for ECDH
- BLAKE2s for hashing and keyed hashing, described in RFC7693
- SipHash24 for hashtable keys
- HKDF for key derivation, as described in RFC5869
> WireGuard's cryptography is essentially an instantiation of Trevor Perrin's Noise framework. It's modern and, again, simple. Every other VPN option is a mess of negotiation and handshaking and complicated state machines. WireGuard is like the Signal/Axolotl of VPNs, except it's much simpler and easier to reason about (cryptographically, in this case) than double ratchet messaging protocols.
> It is basically the qmail of VPN software.
> And it's ~4000 lines of code. It is plural orders of magnitude smaller than its competitors.
Authentication in both directions is achieved with a simple public/private keypair for each peer. Each peer generates these keys during the setup phase, and shares only the public key with other peers.
No other certificates or preshared keys are needed beyond the public/private keys for each node.
Key generation, distribution, and revokation can be handled in larger deployments using a separate service like Ansible or Kubernetes Secrets.
Some services that help with key distribution and deployment:
You can also read in keys from a file or via command if you don't want to hardcode them in `wg0.conf`, this makes managing keys via 3rd party service much easier:
```ini
[Interface]
...
PostUp = wg set %i private-key /etc/wireguard/wg0.key <(cat /some/path/%i/privkey)
-`[Interface]` Make sure to specify a CIDR range for the entire VPN subnet when defining the address the server accepts routes for `Address = 10.0.0.1/24`
-`[Peer]` Create a peer section for every client joining the VPN, using their corresponding remote public keys
-`[Interface]` Make sure to specify only a single IP for client peers that don't relay traffic `Address = 10.0.0.3/32`.
-`[Peer]` Create a peer section for each public peer not behind a NAT, make sure to specify a CIDR range for the entire VPN subnet when defining the remote peer acting as the bounce server `AllowedIPs = 10.0.0.1/24`. Make sure to specify individual IPs for remote peers that don't relay traffic and only act as simple clients `AllowedIPs = 10.0.0.3/32`.
5. Start wireguard on the main relay server with `wg-quick up /full/path/to/wg0.conf`
6. Start wireguard on all the client peers with `wg-quick up /full/path/to/wg0.conf`
7. Traffic is routed from peer to peer using most optimal route over the WireGuard interface, e.g. `ping 10.0.0.3` checks for local direct route first, then checks for route via public internet, then finally tries to route by bouncing through the public relay server.
This is just a standard comment in INI syntax used to help keep track of which config section belongs to which node, it's completely ignored by WireGuard and has no effect on VPN behavior.
#### `Address`
Defines what address range the local node should route traffic for. Depending on whether the node is a simple client joining the VPN subnet, or a bounce server that's relaying traffic between multiple clients, this can be set to a single IP of the node itself (specificed with CIDR notation), e.g. 10.0.0.3/32), or a range of IPv4/IPv6 subnets that the node can route traffic for.
**Examples**
* Node is a client that only routes traffic for itself
`Address = 10.0.0.3/32`
* Node is a public bounce server that can relay traffic to other peers
When the node is acting as the public bounce server, it should set this to be the entire subnet that it can route traffic, not just a single IP for itself.
`Address = 10.0.0.1/24`
* You can also specify multiple subnets or IPv6 subnets like so:
`Address = 10.0.0.1/24,fd42:42:42::1/64`
#### `ListenPort`
When the node is acting as a public bounce server, it should hardcode a port to listen for incoming VPN connections from the public internet. Clients not acting as relays should not set this value.
The DNS server(s) to announce to VPN clients via DHCP, most clients will use this server for DNS requests over the VPN, but clients can also override this value locally on their nodes
**Examples**
* The value can be left unconfigured to use system default DNS servers
Optionally defines which routing table to use for the WireGuard routes, not necessary to configure for most setups.
There are two special values: ‘off’ disables the creation of routes altogether, and ‘auto’ (the default) adds routes to the default table and enables special handling of default routes.
Optionally defines the maximum transmission unit (MTU, aka packet/frame size) to use when connecting to the peer, not necessary to configure for most setups.
The MTU is automatically determined from the endpoint addresses or the system default route, which is usually a sane choice.
There are two special values: ‘off’ disables the creation of routes altogether, and ‘auto’ (the default) adds routes to the default table and enables special handling of default routes.
Defines the VPN settings for a remote peer capable of routing traffic for one or more addresses (itself and/or other peers). Peers can be either a public bounce server that relays traffic to other peers, a directly accessible client via lan/internet that is not behind a NAT and only routes traffic for itself.
All clients must be defined as peers on the public bounce server, however on the simple clients that only route traffic for themselves, only the public relay and other directly accessible nodes need to be defined as peeers. Nodes that are behind separate NATs should not be defined as peers outside of the public server config, as no specific direct route is available between separate NATs. Instead, nodes behind NATs should only define the public relay servers and other public clients as their peers, and should specify `AllowedIPs = 10.0.0.1/24` on the public server that accept routes and bounce traffic to the remote NAT-ed peers.
In summary, all nodes must be defined on the main bounce server. On client servers, only peers that are directly accessible from a node should be defined as peers of that node, any peers that must be relayed by a bounce sherver should be left out and will be handled by the relay server's catchall route.
In the configuration outlined in the docs below, a single server `public-server1` acts as the relay bounce server for a mix of publicly accessible and NAT-ed clients, and peers are configured on each node accordingly:
# routes traffic to itself and entire subnet of peers as bounce server
AllowedIPs = 10.0.0.1/24
PersistentKeepalive = 25
```
#### `# Name`
This is just a standard comment in INI syntax used to help keep track of which config section belongs to which node, it's completely ignored by WireGuard and has no effect on VPN behavior.
#### `Endpoint`
Defines the publicly accessible address for a remote peer. This should be left out for peers behind a NAT or peers that don't have a stable publicly accessible IP:PORT pair. Typically, this only needs to be defined on the main bounce server, but it can also be defined on other public nodes with stable IPs like `public-server2` in the example config below.
This defines the IP ranges that a peer will route traffic for. Usually this is a single address (the VPN address of the peer itself), but for bounce servers this will be a range of the IPs or subnets that the relay server is capable of routing traffic for. Using comma-separated IPv4 or IPv6 CIDR notation, a single address can be defined as routable, or multiple ranges of IPs all the way up to `0.0.0.0/0` to route all internet and VPN traffic through that peer.
When deciding how to route a packet, the system chooses the most specific route first, and falls back to broader routes. So for a packet destined to `10.0.0.3`, the system would first look for a peer advertising `10.0.0.3/32` specifically, and would fall back to a peer advertising `10.0.0.1/24` or a larger range like `0.0.0.0/0` as a last resort.
If the connection is going from a NAT-ed peer to a public peer, the node behind the NAT must regularly send an outgoing ping in order to keep the bidirectional connection alive in the NAT router's connection table.
This value should be left undefined as it's the client's responsibility to keep the connection alive because the server cannot reopen a dead connection to the client if it times out.
The examples in these docs primarily use IPv4, but Wireguard natively supports IPv6 CIDR notation and addresses everywhere that it supports IPv4, simply add them as you would any other subnet range or address.
**Example**
```ini
[Interface]
AllowedIps = 10.0.0.3/24, fd42:42:42::1/64
[Peer]
...
AllowedIPs = 0.0.0.0/0, ::/0
```
### Forwarding All Traffic
If you want to forward *all* internet traffic through the VPN, and not just use it as a server-to-server subnet, you can add `0.0.0.0/0, ::/0` to the `AllowedIPs` definition of the peer you want to pipe your traffic through.
Dynamic allocation of IPs (instead of only having fixed peers) is being developed, the WIP implmentation is available here:
https://github.com/WireGuard/wg-dynamic
You can also build a dynamic allocation system yourself by reading in IP values from files at runtime by using `PostUp` (see below).
**Example**
```ini
[Interface]
...
PostUp = PostUp = wg set %i allowed-ips /etc/wireguard/wg0.key <(some command)
```
### Other WireGuard Implementations
- https://git.zx2c4.com/wireguard-go/about/
A compliant userland WireGuard implementation written in Go.
- https://github.com/cloudflare/boringtun
A compliant WireGuard implementation with the exact same API, written in Rust.
See https://blog.cloudflare.com/boringtun-userspace-wireguard-rust/
Both of these are slower than the native C version that runs in kernel land, but provide other benefits by running in userland (e.g. easier containerization).
WireGuard will ignore a peer whose public key matches the interface's private key. So you can distribute a single list of peers everywhere, and only define the `[Inteface]` separately on each server.
Each peer has its own `/etc/wireguard/wg0.conf` file, which only contains it's `[Interface]` section.
Each peer also has a shared `/etc/wireguard/peers.conf` file, which contains all the peers.
The `wg0.conf` file also has a `PostUp` hook, calling `wg addconf /etc/wireguard/peers.conf`.
It's up to you to decide how you want to share the `peers.conf`, be it via a proper orchestration platform, something much more pedestrian like Dropbox, or something kinda wild like Ceph. I dunno, but it's pretty great that you can just wildly fling a peer section around, without worrying whether it's the same as the interface.
#### Setting config values from files or command outputs
You can set config values from arbitrary commands or by reading in values from files, this makes key management and deployment much easier as you can read in keys at runtime from a 3rd party service like Kubernetes Secrets or AWS KMS.
WireGuard can be run in Docker with varying degrees of ease. In the simplest case, `--privileged` and `--cap-add=all` args can be added to the docker commands to enable the loading of the kernel module.
Setups can get somewhat complex are are highly dependent on what you're trying to achieve. You can have WireGuard itself run in a container and expose a network interface to the host, or you can have WireGuard running on the host exposing an interface to specific containers.
The complete example config for the setup below can be found here: https://github.com/pirate/wireguard-docs/tree/master/full-example (WARNING: do not use it on your devices without chaning the public/private keys!).
These 5 devices are used in our example setup to explain how WireGuard supports bridging across a variety of network conditions, they're all under an example domain `example-vpn.dev`, with the following short hostnames:
-`public-server1` (not behind a NAT, acts as the main VPN bounce server)
-`public-server2` (not behind a NAT, joins as a peer without bouncing traffic)
-`home-server` (behind a NAT, joins as a peer without bouncing traffic)
-`laptop` (behind NAT, sometimes shared w/ home-server/phone, sometimes roaming)
-`phone` (behind NAT, sometimes shared w/ home-server/laptop, sometimes roaming)
This VPN config simulates setting up a small VPN subnet `10.0.0.1/24` shared by 5 nodes. Two of the nodes (public-server1 and public-server2) are VPS instances living in a cloud somewhere, with public IPs accessible to the internet. home-server is a stationary node that lives behind a NAT with a dynamic IP, but it doesn't change frequently. Phone and laptop are both roaming nodes, that can either be at home in the same LAN as home-server, or out-and-about using public wifi or cell service to connect to the VPN.
Whenever possible, nodes should connect directly to eachother, depending on whether nodes are directly accessible or NATs are between them, traffic will route accordinly:
`public-server1` acts as an intermediate relay server between any VPN clients behind NATs, it will forward any 10.0.0.1/24 traffic it receives to the correct peer at the system level (WireGuard doesn't care how this happens, it's handled by the kernel `net.ipv4.ip_forward = 1` and the iptables routing rules).
Each client only needs to define the publicly accessible servers/peers in it's config, any traffic bound to other peers behind NATs will go to the catchall `10.0.0.1/24` for the server and will be forwarded accordingly once it hits the main server.
In summary: only direct connections between clients should be configured, any connections that need to be bounced should not be defined as peers, as they should head to the bounce server first and be routed from there back down the vpn to the correct client.
To run this full example, simply copy the `full wg0.conf config file for node` section from each node onto each server, enable IP forwarding on the public relay, and then start WireGuard on all the machines.
For more detailed instructions, see the [Quickstart](#Quickstart) guide and API reference above. You can also download the complete example setup here: https://github.com/pirate/wireguard-docs/tree/master/full-example (WARNING: do not use it on your devices without chaning the public/private keys!).
For more detailed instructions, see the [Quickstart](#Quickstart) guide and API reference above. You can also download the complete example setup here: https://github.com/pirate/wireguard-example.
