This will show you the basics of securely connecting to hosts via SSH.

SSH

This should give you some of the basic commands required for using SSH to remote into another device. I'll also show you how to create and use SSH keys for authentication to those devices.

Connect to Client

To connect to a client via ssh:

ssh <username>@<ip_or_domain_name>

The username must be a user on the device you are connecting to.

If the device is not using the standard port of 22:

ssh -p <port_number> <username>@<ip_or_domain_name>

Creating and Using SSH Keys

Using SSH keys is generally better than a password for authentication. This is because a key is longer and more complex than a memorable password. You are also able to set passphrases on keys to add an extra layer of security if the key is stolen somehow.

1. Create an SSH key on your localhost:

ssh-keygen

OR

ssh-keygen -b 4096

The second command generates a longer 4096 bit key. The command will have generated two files id_rsa, the private key, and id_rsa.pub, the public key. By default these will be stored in the current directory unless you specify otherwise. Copy the public key to the .ssh directory.

cp id_rsa.pub ~/.ssh/

2. Next step is to create and take ownership of a .ssh folder on the device you want to connect to:

mkdir ~/.ssh

chmod 700 ~/.ssh

touch ~/.ssh/authorized_keys

chmod 600 ~/.ssh/authorized_keys

3. Now copy the public key from the localhost to the device you want to connect to:

scp .ssh/id_rsa.pub <username>@<ip_or_domain_name>:~/id.rsa.pub

For more information on SCP see below, or use the manual page.

4. Now put that key into the authorized_keys folder you created earlier (on the host you want to connect to):

cat id_rsa.pub >> ~/.ssh/authorized_keys

Then delete the file id_rsa.pub file from the host (This is a cleanup task, and is not required):

rm id_rsa.pub

You should now be able to connect from the localhost to the host via SSH without entering a password.

N.B. You may be prompted to enter a passphrase on connection, if you have not set one simply hit the Enter key

SCP

There are ways you can use SCP.

Send to Host

To send a file to the host machine:

scp ./foo.txt <username>@<ip_or_domain_name>:/home/<username>/

1. ./foo.txt - This is the file you are copying to the host.
2. <username>@<ip_or_domain_name> - This is the user and location of the host you are copying to.
3. :/home/<username>/ - This is the directory you are copying the file to.

Copy from Host

To copy a file from a host device:

scp <username>@<ip_or_domain_name>:/home/<username>/foo.txt ./bar.txt

1. <username>@<ip_or_domain_name> - This is the user and location of the host you are copying from.
2. :/home/<username>/foo.txt - This is the directory you are copying the file from.
3. ./bar.txt - This is the location you are copying the file to on your device.

Specify Port

To specify the port on to send the file over and send a whole directory:

scp -P <port_number> -r <directory_location> <username>@<ip_or_domain_name>:/home/<username>/