The dual-license on OpenSSL clashes with the more restrictive GPL
licensing on VTun.  In most cases, an exemption on the GPL-licensed
product is ultimately required to ensure no barrier exists to using it
with a project licensed under a less restrictive license, legally
speaking.

Historically, VTun binaries have been linked with OpenSSL encryption
libraries and distributed in combination.  A de-facto licensing
exemption has openly existed only with respect to linking VTun code
against OpenSSL libraries as well as distribution within projects also
incorporating OpenSSL.  To that end, and to clear up a question about
linking raised with OpenSSL, a special exemption is hereby granted:

Permission is given to link the code of this program with the OpenSSL
library, or with modified versions of OpenSSL that use the same
license as OpenSSL, and to distribute linked combinations including
the two, so long as no other component within this program or the
resulting distribution forbids a coupling.