underlying the four contexts, each threat is followed by a discussion of the possible countermeasures, along with countermeasures used in other contexts that may be relevant.

Threat 1. Free riding, or asymmetry between giving and receiving. Asymmetry manifests itself as a lack of contributed resources for maintaining and improving the common pool of resources [ 2].

Contexts. OSS. OSS lends itself to free riding, as no contribution is requested in return for the use of freely available resources [ 12]. Countering the threat involves motivating potential contributors. This can be done by highlighting contributor benefits: learning from the expertise of peers in a technical community [ 6, 12]; being able to tailor software to one’s personal needs [ 12]; having fun [ 9]; having the opportunity to signal status [ 5], potentially enhancing employment prospects [ 6, 10]; having the opportunity to support self identification [ 4]; and having the opportunity to help others.

Computing grids. In two-way grids, asymmetry of resource contributions can be countered through agreements amongusers to align

Nonexcludable High

receipt levels with contribution levels. In one-way _Low grids, motivation to contribute is required in order to reduce free riding. The literature is limited on grid contribution motivations, but according to a SETI@home survey, the main one is “the good of humanity” (59% of respondents). Other motivations may include the performance of competing contributor groups. Motivations revealed in other contexts could also support contribution, including the public display of one’s abilities, the prospect of self identification, and status signaling.

Wireless networks. Free riding manifests itself when a user password-protects his or her own access point or shuts it down when not using the commons [ 2]. Here, too, an effort to encourage the motivations discussed in the other contexts, including the prospect of self-identification and status signaling, helps reduce free riding.

Content. Like other nonexcludable goods, content lends itself to free riding. To mitigate against the limitations of online cooperation and collective action, online networks require ongoing interaction, identity persistence, and knowledge of previous interactions [ 5]. Other potential countermeasures discussed in the literature include: making people publicly commit to

Table 2. Typology of GARN-facilitated goods.

contribution; increasing social validity by demonstrating to potential contributors that many people like themselves have benefited from contributions; and creating contribution ratings by participants who rank contributors highly (the Slashdot model) [ 1]. In addition, countermeasures used in the OSS context may be useful, including incentives, such as the opportunity to display one’s abilities and the opportunity to signal status and help others.

Threat 2. Use of others’ resources without their
knowledge or consent.

Contexts. OSS. Because OSS is nonexcludable, project hijacking is a potential threat, such as when an

OSS is packaged with proprietary code in order to
take it private [ 8]. Countermeasures include: adopting
software that restricts proprietary appropriation;
encouraging compliance with licensing terms through
normative and legal sanctions; incorporation as a way
to protect individual contributors from liability;
transferring individual property rights to nonprofit
corporations; trademarking a project’s brands and
logos; trademarking a
foundation; and protect-
Nonrival
ing a project’s brand [ 8].
Computing grids. The
threat is not significant in
_{Computing grids} the grid context as long as
-Collective good contributing computers
are protected from unau-

thorized access (excludability). Failure to provide this protection can result in others using their processing power or storage capacity. Ways to prevent the unwarranted use of resources includes: monitoring traffic; building firewalls; and establishing legal agreements among grid parties.

Wireless networks. Taking over contributors’ devices is a significant threat; access is nonexcludable, making this commons good susceptible to the “tragedy of the commons.” This threat can be countered through various security products [ 2]. In closed commons, it can be countered by monitoring the network for bandwidth use and removing devices that continuously overuse bandwidth [ 2].

Content. The threat here is the use of knowledge-based content produced without acknowledging the source. As both knowledge-based content and OSS are public goods, this threat can be countered in ways similar to the open-source software tactics identified in [ 8]. For example, Wikipedia is copyrighted, and proprietary appropriation is prohibited; Wikipedia is incorporated, and its contributors are protected from liability; individual property rights are transferred to a nonprofit foundation; and the Wikipedia brand is trademarked.

Low

Wireless LAN -Commons good

High

OSS, wiki-based content -Public good