電子郵件在我們現今生活中已不可或缺,
現代電子郵件系統架構幾乎都是集中式伺服器架構,
使用者透過郵件伺服器來幫忙轉送郵件。
由於電子郵件的便利性與低成本,
對於攻擊者而言,
只要取得有效的郵件地址即可濫發大量的垃圾郵件做為廣告用途,
目前主要的反垃圾郵件機制大部分為內容過濾法。
帳號蒐集攻擊利用暴力法的形式蒐集特定網域下的有效郵件帳號,
是攻擊者時常採用的一種攻擊手段。
點對點架構以分享電腦資源為目的,
不需要中央伺服器,
具有較好的容錯性、穩定性及延展性。
本論文提出在點對點架構下,
帳號蒐集攻擊的防治法,
以節省網路資源為目的。
實驗結果也會證明我們的方法是有效果的。

The e-mail service is indispensable to our daily lives.
Modern e-mail systems are based on the client-sever design,
where attackers may distribute spam e-mails and most anti-spam mechanisms rely on the content-filter-based approach.
The email directory harvest attack (DHA) is a special form of brute force attack.
The attacker attempts to gain information about email addresses used in a domain name.
Peer-to-peer architectures share computer resources by direct exchange,
rather than requiring a centralized server.
Applications on peer-to-peer networks are scalable, fault-resilient, and reliable.
In this thesis we present a defence mechanism,
where the content filtering is optional,
against DHA in a messaging system based on the peer-to-peer network.
Simulations show that our approach successfully blocks spam messages from spreading and identifies spammers.

[1] 財團法人台灣網路資訊中心,“http://www.twnic.net.tw.”.

[2] 亞太垃圾信研究中心,“http://asrc.softsqr.com.”.

[3] Barracuda Networks,“http://www.barracudanetworks.com.”.

[4] A. I. T. Rowstron and P. Druschel,“Pastry: Scalable, decentralized object location, and routing for large-scale peer-to-peer systems,” Middleware’01: Proceedings of the IFIP/ACM International Conference on Distributed Systems Platforms Heidelberg, pp. 329–350, 2001.

[5] A. Mislove, A. Post, C. Reis, P. Willmann, P. Druschel, D. S. Wallach, X. Bon- naire, P. Sens, J.-M. Busca, and L. Arantes-Bezerra,“Post: a secure, resilient, cooperative messaging system,” HOTOS’03: Proceedings of the 9th conference on Hot Topics in Operating Systems, pp. 61–66, 2003.

[6] S. Ratnasamy, P. Francis, M. Handley, R. Karp, and S. Schenker,“A scalable content-addressable network,” SIGCOMM ’01: Proceedings of the 2001 con- ference on Applications, technologies, architectures, and protocols for computer communications, pp. 161–172, 2001.

[7] I. Stoica, R. Morris, D. Karger, M. F. Kaashoek, and H. Balakrishnan, “Chord: A scalable peer-to-peer lookup service for internet applications,” SIGCOMM Computer Communication Review, vol. 31, no. 4, pp. 149–160, 2001.

[8] 中國反垃圾郵件聯盟,“http://www.anti-spam.org.cn.”.

[9] 林宜隆, 陳蕾琪, “電子垃圾郵件管理相關法律問題之研究,”2001全國科技法律研討會, 2001.

[10] S. Hird,“Technical solutions for controlling spam,” Proceedings of the Annual Meeting of the Australian UNIX and Open Systems User Group, 2002.

[11] 國家通訊傳播委員會,“http://www.ncc.gov.tw.”

[12] N. Zhang, Y. Jiang, B. Fang, L. Guo, and X. Cheng, “A traffic-classified tech- nique for filtering spam from bulk delivery e-mails,” 2006 IEEE International Performance Computing and Communications Conference, pp. 239–246, 2006.

[13] Grey List, “http://www.greylisting.org.”.

[14] D. Geer, “Will new standards help curb spam?,” IEEE Computer Society mag- azine, vol. 37, pp. 14–16, February 2004.

[15] J. T. Goodman and R. Rounthwaite, “Stopping outgoing spam,” EC ’04: Pro- ceedings of the 5th ACM conference on Electronic commerce, pp. 30–39, 2004.

[16] K. Yoshida, F. Adachi, T. Washio, H. Motoda, T. Homma, A. Nakashima, H. Fujikawa, and K. Yamazaki, “Density-based spam detector,” KDD ’04: Proceedings of the tenth ACM SIGKDD international conference on knowledge discovery and data mining, pp. 486–493, 2004.

[17] S. Androutsellis-Theotokis and D. Spinellis,“A survey of peer-to-peer content distribution technologies,” ACM Computing Surveys, vol. 36, no. 4, pp. 335–371, 2004.

[18] M. Castro, P. Druschel, Y. Hu, and A. Rowstron, “Topology-aware routing in structured peer-to-peer overlay networks,” Technical Report MSR-TR-2002-82, Microsoft Research, One Microsoft Way, Redmond, WA 98052, 2002.

[19] P. Druschel and A. Rowstron, “Past: A large-scale, persistent peer-to-peer stor- age utility,” HOTOS ’01: Proceedings of the Eighth Workshop on Hot Topics in Operating Systems, pp. 75–80, 2001.

[20] M. Castro, P. Druschel, A.-M. Kermarrec, and A. Rowstron, “Scribe: a large- scale and decentralized application-level multicast infrastructure,” IEEE Jour- nal on Selected Areas in Communications, vol. 20, pp. 1489–1499, Oct 2002.

[21] B. Vajda,“Efficient directory harvest attacks,” Proceedings of the 2005 International Symposium on Collaborative Technologies and Systems, pp. 62–68, 2005.