by using ubuntu you Must to send and receive packets between two computers ( write program by using C langug )

but this program MUST be inclod authentication & confidentiality services are deployed using relevant protocols at different layers, for instance TLS, SSL or IPSec.

than use Wireshark to display the protocols if it work when you Make transmit packets

for examples:

use matching user name & password for authentication use hashing to provid confidentiality