The dual-license on OpenSSL clashes with the more restrictive GPL licensing on LZO. 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. Markus Oberhumer granted an exemption to VTun with respect to clashing licenses and OpenSSL on 5 May 2003, with the following comments: Message-Id: <20030505155258.3025c056.markus@oberhumer.com> > Hi, > > Anyway, I hope the following paragraph will suffice: > > Hereby I grant a special exception to the VTun project > (http://vtun.sourceforge.net) to link the LZO library with > the OpenSSL library (http://www.openssl.org). > > Markus F.X.J. Oberhumer > > Regards, > Markus