A new covert channel over the RTP protocol is designed and implemented by modifying the timestamp value in the RTP header. Due to the high frequency of RTP packets, the covert channel has a high bit-rate, theoretically up to 350 bps. The broad use of RTP for multimedia applications such as VoIP, provides abundant opportunities to such a covert channel to exist. By using the RTP header, many of the challenges present for covert channels using the RTP payload are avoided. A reference implementation of this covert channel is presented. Bit-rates of up to 325 bps were observed. The channel is very difficult to detect due to expected variations in the timestamp field and the flexible nature of RTP.

Date of creation, presentation, or exhibit



Proceedings of the 9th International FLINS Conference
Emei, Chengdu, China, 2 – 4 August 2010

Electronic version of an article published at [World Scientific Proceedings Series on Computer Engineering and Information Science, 4, 2010, 813-819, © 2010 World Scientific Publishing Company,

Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works in February 2014.

Document Type

Conference Paper

Department, Program, or Center

Department of Computing Security (GCCIS)


RIT – Main Campus