in june 2001, triggered by concerns over darren reed's modification of ipfilter's license wording, a systematic license audit of the openbsd ports and source trees was undertaken. code in more than a hundred files throughout the system was found to be unlicensed, ambiguously licensed or in use against the terms of the license. to ensure that all licenses were properly adhered to, an attempt was made to contact all the relevant copyright holders: some pieces of code were removed, many were replaced, and others, such as the multicast routing tools and , were relicensed so that openbsd could continue to use them. also removed during this audit was all software produced by daniel j. bernstein. at the time, bernstein requested that all modified versions of his code be approved by him prior to redistribution, a requirement to which openbsd developers were unwilling to devote time or effort.