The SSH Server app from Ice Cold Apps enables you to SSH into any Android device. I use this to SSH from my Ubuntu computers to my Android devices, both connected to my home wireless network.
If you have not rooted your phone, you will not be able to access privileged directories and files. You will also have to pick a port number that is bigger than 1024.
First, create a Server and create a User in the app. Remember to specify a port number that is bigger than 1024. Start the server to run the SSH server.
SSH to the Android device using its IP address, the username you created and the port you specified. You will be asked to accept its key and will be prompted to enter the password you specified earlier:
$ ssh firstname.lastname@example.org -p 1700
Tried with: SSH Server 3.1, Moto G2 (XT1068) and Ubuntu 14.04