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2. AnalogBit: tcp-over-dns,
http://analogbit.com/software/tcp-over-dns
3. Beardsley, T.: Weekly Metasploit Update: DNS payloads, Exploit-DB, and More. Rapid7 Blog Post (March 2012),
https://community.rapid7.com/community/metasploit/blog/2012/03/28/metasploit-update
4. Binsalleeh, H., Youssef, A.: An implementation for a worm detection and mitigation system. In: Proc. 24th Biennial Symposium on Communications, pp. 54–57 (June 2008)
5. Born, K., Gustafson, D.: Detecting DNS tunnels using character frequency analysis. In: Proceedings of the 9th Annual Security Conference (April 2010)