Notes: Kernel version 3.19 has a bug which means juniper VPN will not work. If you are running this kernel version you will need to upgrade to a newer kernel version to resolve this issue. If you are running 15.04 you can upgrade to Linux kernel 4.
Juniper VPN kindly do not offer a 64bit deb package for Ubuntu users. This means you need to find a way to install and run the VPN on your own. With Ubuntu 15.04 being relatively new at the time of writing this may be a little more difficult than it needs to be for some users.
Hopefully this installation guide will get you up and running with little fuss.
First I started by installing openjdk and the icedtea plugin and xterm:
sudo apt-get install openjdk-7-jdk icedtea-7-plugin xterm
Followed by installing the 32bit version of the openjdk 7.
sudo apt-get install openjdk-7-jre:i386
Once installed you should check that update-alternatives is sym-linked in
/usr/sbin/ this can be done by running the command:
ln -s /usr/bin/update-alternatives /usr/sbin/
Update the java version being used by update-alternatives to be
sudo update-alternatives --config java # select the option which is the recently downloaded java-7-openjdk-amd64/jre/bin/java
At this point if you try to run the juniper network tool you may get an error saying 32bit library files are missing. You will need to install the following packages so these errors do not appear.
sudo apt-get install libstdc++6:i386 lib32z1 lib32ncurses5 lib32bz2-1.0 libxext6:i386 libxrender1:i386 libxtst6:i386 libxi6:i386 libbz2-1.0:i386
Now restart firefox and log into the juniper vpn. You should now be able to access and install the VPN client software.