I'm working through Intrusion Detection With BASE And Snort tutorial (http://www.howtoforge.com/intrusion_detection_base_snort_p3) on Ubuntu. I ran into a problem at make/install LIBPCAP (page 3). When I execute ./configure, I get the following error: configure: error: Your operating system's lex is insufficient to compile libpcap. flex is a lex replacement that has many advantages, including being able to compile libpcap. For more information, see http://www.gnu.org/software/flex/flex.html. I'm familiar with Linux and Ubuntu, but not knowlegeable enough to know how to resolve this problem. Can anyone help? Bruce