https://www.gns3.com/support/docs/linux-installation
sudo dpkg --add-architecture i386
sudo add-apt-repository ppa:gns3/ppa
sudo apt-get update
sudo apt-get install gns3-gui
http://www.juniper.net/support/tools/srxha/
A Cisco router: Cisco IOS Software, 3600 Software (C3640-JK9S-M), Version 12.4(16)
A Juniper router: JunOS Olive 12.1R1.9 (in VirtualBox)
A Vyatta router: Brocade Vyatta 5415 vRouter 6.7 R9T60 (in VirtualBox)
A Linux machine: Ubuntu (in VirtualBox)