--- sidebar_label: VPN --- # zrok VPN Guide zrok VPN backend allows for simple host-to-host VPN setup. ## Operating System Requirements zrok VPN requires elevated privileges to manage network devices. ### Windows On Windows, you must run zrok VPN commands as an administrator and install Wintun by placing `wintun.dll` ([download link](https://www.wintun.net/)) in the same directory as the `zrok.exe` executable. ### Linux On Linux, the simplest way to grant the necessary privileges is to run zrok VPN commands as root. You can enable a separate environment for root by also running `zrok enable` as the root user, or you can prefix the commands like `sudo -E` to allow zrok running as root to use the zrok environment owned by the current user. The minimum privilege is runing zrok VPN commands and the `ip` command with the `NET_ADMIN` kernel capability. The `zrok-share.service` unit has a commented example to grant `NET_ADMIN` as an Ambient Capability. ### macOS On macOS, you must run zrok VPN commands as root. You can prefix the zrok command with `sudo -E` to allow zrok running as root to use the zrok environment owned by the current user. ## Start the VPN Server VPN is shared through the `vpn` backend of `zrok` command. ```bash eugene@hermes $ sudo -E zrok share private --headless --backend-mode vpn [ 0.542] INFO sdk-golang/ziti.(*listenerManager).createSessionWithBackoff: {session token=[589d443c-f59d-4fc8-8c48-76609b7fb402]} new service session [ 0.705] INFO main.(*sharePrivateCommand).run: allow other to access your share with the following command: zrok access private 3rq7torslq3n [ 0.705] INFO zrok/endpoints/vpn.(*Backend).Run: started ``` ![VPN share](./vpn-share.png) `sudo` or equivalent invocation is required because VPN mode needs to create a virtual network device (`tun`) `-E` option allows `zrok` to find your zrok configuration files (in your `$HOME/.zrok`) By default `vpn` backend uses subnet `10.122.0.0/16` and assigns `10.122.0.1` to the host that stared VPN share. Example output from `ifconfig`: ```text tun0: flags=4305 mtu 16384 inet 10.122.0.1 netmask 255.255.0.0 destination 10.122.0.1 inet6 fe80::705f:24e4:dcfc:a6b2 prefixlen 64 scopeid 0x20 inet6 fd00:7a72:6f6b::1 prefixlen 64 scopeid 0x0 unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 txqueuelen 500 (UNSPEC) RX packets 0 bytes 0 (0.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 27 bytes 3236 (3.2 KB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 ``` Default IP/subnet setting can be overridden by adding `` parameter: ```bash sudo -E zrok share private --headless --backend-mode vpn 192.168.42.12/24 ``` ## Reserve a VPN Share Token As with all backend modes, you can reserve a share token for a VPN share. ```bash eugene@hermes $ zrok reserve private --backend-mode vpn [ 0.297] INFO main.(*reserveCommand).run: your reserved share token is 'k77y2cl7jmjl' eugene@hermes $ sudo -E zrok share reserved k77y2cl7jmjl --headless [ 0.211] INFO main.(*shareReservedCommand).run: sharing target: '10.122.0.1/16' [ 0.211] INFO main.(*shareReservedCommand).run: using existing backend target: 10.122.0.1/16 [ 0.463] INFO sdk-golang/ziti.(*listenerManager).createSessionWithBackoff: {session token=[22c5708d-e2f2-41aa-a507-454055f8bfcc]} new service session [ 0.641] INFO main.(*shareReservedCommand).run: use this command to access your zrok share: 'zrok access private k77y2cl7jmjl' [ ``` ## Access the VPN Share ```bash eugene@calculon % sudo -E zrok access private --headless k77y2cl7jmjl [ 0.201] INFO main.(*accessPrivateCommand).run: allocated frontend '50B5hloP1s1X' [ 0.662] INFO main.(*accessPrivateCommand).run: access the zrok share at the following endpoint: VPN: [ 0.662] INFO main.(*accessPrivateCommand).run: 10.122.0.1 -> CONNECTED Welcome to zrok VPN [ 0.662] INFO zrok/endpoints/vpn.(*Frontend).Run: connected:Welcome to zrok VPN ``` zrok creates a virtual network device, i.e., a "tun" interface, when you run `zrok access`. Example output from `ifconfig` run on a VPN client device: ```bash utun5: flags=8051 mtu 1500 inet 10.122.0.3 --> 10.122.0.1 netmask 0xff000000 inet6 fe80::ce08:faff:fe8a:7b25%utun5 prefixlen 64 scopeid 0x14 nd6 options=201 ``` At this point a VPN tunnel is active between your server and client. In the example above server is `hermes(10.122.0.1)` and client is `calculon(10.122.0.3)`. All devices in the VPN can access one another by IP address. ```bash eugene@calculon ~ % ssh eugene@10.122.0.1 Welcome to Ubuntu 23.10 (GNU/Linux 6.5.0-27-generic x86_64) * Documentation: https://help.ubuntu.com * Management: https://landscape.canonical.com * Support: https://ubuntu.com/pro 0 updates can be applied immediately. Last login: Tue Apr 16 09:27:13 2024 from 127.0.0.1 eugene@hermes:~$ who am i eugene pts/8 2024-04-16 10:04 (10.122.0.3) eugene@hermes:~$ ``` You can also make a reverse(server-to-client) connection: ```bash eugene@hermes:~$ ssh 10.122.0.3 Last login: Tue Apr 16 09:57:28 2024 eugene@calculon ~ % who am i eugene ttys008 Apr 16 10:06 (10.122.0.1) ```