Appended to this message, you will find my script (currently only partly done), the last 100 lines of an strace, and the output of a gdb backtrace. ruby -v outputs: ruby 1.6.8 (2002-12-24) [i386-linux] The function of the program is to listen on a network interface promiscuously and output records of packets which do not match a set of filters, and to verify that traffic is being observed that does match each of the filters in the set. The program uses Ruby/PCap. I am currently using the debian package libpcap-ruby version 1.6-4 The program runs for about 10 minutes, then segfaults. Apparently, my news program can't attach files. So, I'll throw these onto a web site. Check out http://capsaicin.ca/rubydebug/ :) Can anyone help me? Is this a nice obvious bug? Thanks, Mathew Johnston