16.04 - Unable to ssh into a machine unless on the same network - Ask Ubuntu

i trying ssh home laptop(ubuntu 16.04), on private network, ip 10.12.x.x, work machine, @ university network, ip 10.100.x.y, running ubuntu 16.04.

i unable establish connection , "connection timed out" message. if try ssh when laptop on same network work computer,it works flawlessly.

any thoughts why happens?

you can't connect private network outside. university have give public ip machine want connect to. have handle port forwarding end send desired traffic (ie specific ports) machine.

the same goes if want connect home computer university. home computer on router. have connect public ip (most ip of router or provide modem ip) have traffic forwarded private ip of computer.

the options in modem's setup port forwarding in firewall or security section.

companies allow outside networking , connecting computers provide vpn (virtual private network) connectivity provide remove facilities ip of vpn can connected on same network different location.

there other variations , schemes can used basic gist.

by way, can public 'ip address' in number of ways including clicking on link such what public ip address.