Nowadays, threats of information security have become a big issue in internet environments. Various security solutions are used as such problems’ countermeasure; IDS, Firewall and VPN. However, a TCP/IP protocol based Internet basically has great vulnerability of protocol itself. It is especially possible to establish a covert channel using TCP/IP header fields such as identification, sequence number, acknowledgement number, timestamp and so on [3]. In this paper, we focus on the covert channels using identification field of IP header and the sequence number field of TCP header. To detect such covert channels, our approach uses a Support Vector Machine which has excellent performance in pattern classification problems. Our experiments showed that the proposed method could discern the abnormal cases(including covert channels) from normal TCP/IP traffic using a Support Vector Machine.