(Free) Virtual Networks (VPNs)

• ChaosVPN: http://wiki.hamburg.ccc.de/ChaosVPN
• Gh0st Networks: http://www.gh0st.net/
• Hacking Lab: https://www.hacking-lab.com/
• http://p0wnlabs.com/
• https://pwn0.com/
• PentestIT: https://lab.pentestit.ru/

Custom Personal Targets

• Hack A Server: https://hackaserver.com/
• Hack Me: http://hack.me/
• Hack This: https://www.hackthis.co.uk/
• Smash The Stack: http://smashthestack.org/
• Hack The Box: https://www.hackthebox.gr/
• SecAdvise: https://labs.secadvise.com/
• DarkHive: http://darkhive.net/
• Avatao: https://avatao.com/
• Root-Me: https://www.root-me.org/