The java library I need (jpcap) only works on Java 6, it won't work with Java 7. Is it still possible to install Java 6 on Ubuntu? According to the Ubuntu Help:
Oracle (Sun) Java 6 is no longer available to be distributed by Ubuntu, because of license issues
I've tried to use the instructions on the same site but they don't seem to work...
./jre-6u34-linux-i586.bin doesn't seem to do anything!
Check out these instructions on how to install Sun JDK 6. In older versions of the repositories the desired package is included.
If you're not obliged to, try using jNetPcap instead. It's another wrapper around pcap, it just works on more recent JVMs and is not restricted to 32 bit architecture.