Preventing Trivial Malicious Access to Your Linux Server

One of the problem haunting Linux server installation on the internet is malicious accesses, such as port scanning. One of the lightweight option to run in your Linux server to provide protection against "trivial" malicious activity from the internet is the psad (http://cipherdyne.org/psad/). This solution uses iptables as the source for analysis.

Introduction to IP and ISDN

I didn't realize until just now that there is a very good introduction to IP+ISDN networks in the office web page :P. Well, not until the DNS relay/caching talks surfaced.
For those interested in the subject, this is the link:
http://www.abilis.net/fileadmin/tutorial/en/index.html

Even though the tutorial mainly talks about the Abilis product, the tutorial contains a lot of primer on IP+ISDN network architecture.