Recently computer system attacks which travel across networks are increasing. And the concern with network security has been growing. It seems that many network adminstrators are worried about the method which eliminates their network security vulnerabilities. This paper describes an introduction example of the intrusion detection software which is called RealSecure. First, many problems of the software are reported. On the other hand, advantages of the software are reported. Next, the real attacks which was detected by the software are listed. Lastly I propose an improvement method of network security. And the effect of the method is described. I hope to help many network administrators to examine the introduction of an intrusion detection software.

We have developed Web based E-mail client software supporting IMAP4 protocol named "WebMailer". Users can use E-mail from everywhere by using only Web browser without any setups, and access their own mailbox in their mail-server via IMAP4 protocol securely. The WebMailer provides a convenient E-mail environment for users. It also reduces maintenance costs for running E-mail systems. This paper describes details of the WebMailer.