Wireshark is distributed under the GNU GPL version 2. There are no restrictions on its use. There are significant restrictions on its distribution. Parts of Wireshark can be built and distributed as libraries. These parts are still covered by the GPL, and NOT by the Lesser General Public License or any other license. If you create a combined work using all or part of Wireshark, then your combined work must be released under a license compatible with the GPL. ...and don't get us started on trademarks. The full text of the GNU GPL may be viewed in /usr/share/common-licenses/GPL-2.