How to add TAP adapter interface in Windows

This article was useful to add interface into Windows OS quickly. Also this differentiation between TAP and TUN.

Acronyms explanation:

TAP = Terminating Access Point

TUN = Terminating Unbroadcasting Node

VPN = Virtual Private Network

How to insert non-breaking hyphen

Here is non-breaking hyphen: ‑. You can copy & paste it freely where you want (it is open-source).

It was forked from this one (credit them for the original work).

OpenConnect as Cisco AnyConnect VPN client better alternative

Cisco AnyConnect VPN client is sometimes too restrictive (e.g. disconnecting internet on client side, when split tunnelling is not configured on server side, or running under privileged user - root or SYSTEM), and there comes OpenConnect giving more freedom to the user.

OpenConnect is truly multi-platform and partially also OpenConnect-GUI bundling OpenConnect for Windows and macOS. This GUI wrapper gives to using OpenConnect very similar way and feeling, as GUI of Cisco AnyConnect VPN client.

In Windows, after VPN connection established, if "split tunnelling" is not allowed on (Cisco) VPN server (concentrator), this can be bypassed on client side by increasing metric of TAP interface (to be higher than metric of physical network interface), and configuration of routes (slices) to be routed to VPN, but not anything other. This can be done e.g. via administrative shell (cmd.exe):

route add <IPsubnet> mask <mask> <IPdefaultGW-VPN> IF <IFnumber>
netsh interface ip set interface <IFnumber> metric=5

Routes, interfaces, default gateways, etc., can be displayed this way:

route print

Above commands may be chained (e.g. within the BAT file) this way (see https://stackoverflow.com/questions/8055371/how-do-i-run-two-commands-in-one-line-in-windows-cmd for details):

cmd /k "route print & route-add-command & netsh-interface-command & route print"

For macOS, this GUI wrapper is experimental, so OpenConnect can be installed also directly, not as part of GUI bundle (with sample usage with vpn-slice, to do client-side "split tunnelling" - allowing internet usage bypassing VPN):

(sudo) brew install openconnect
(sudo) brew install vpn-slice
(sudo) openconnect https://<address> -s 'vpn-slice <IPsubnet>/<mask>'

Similar setup should be possible also in Linux.

More info:

• routing table modification in Windows
• vpn-slice (currently lacking Windows OS support)
• using netstat and route on Oracle Solaris