SSH Connect from Ubuntu

Synonyms:

Connect your server from Ubuntu using SSH keys file

connect from local machine A (also could be a remote server) to remote server B is quite easy using ssh keys file.

Prerequisite

$[username]$

Both machines are using the same user account $username$. If not, Create ubuntu account first. Always use the same username will make life much easier.

Local Machine A config private key

generate ssh keys file

ssh-keygen -t ed25519 -C "roger@home"
cat ~/.ssh/id_ed25519
cat ~/.ssh/id_ed25519.pub

id_ed25519 is the private key that should never share with others.
id_ed25519.pub is the public key that need to tell other severs.

already have the private key?

$[texteditor]$

mkdir -p ~/.ssh && chmod 0700 ~/.ssh/ && touch ~/.ssh/id_ed25519 && chmod 0600 ~/.ssh/id_ed25519 && $texteditor$ ~/.ssh/id_ed25519

then fill your private key

remote server B config public key

mkdir -p ~/.ssh && chmod 0700 ~/.ssh/ && touch ~/.ssh/authorized_keys && chmod 0600 ~/.ssh/authorized_keys && $texteditor$ ~/.ssh/authorized_keys

then add your public key

ssh connect from A to B

$[b_hostname]$

ssh $b_hostname$

disable password authentication of server B(optional)

sudo $texteditor$ /etc/ssh/sshd_config

PasswordAuthentication no

sudo /etc/init.d/ssh restart

disable direct root login of server B(optional)

sudo $texteditor$ /etc/ssh/sshd_config

PermitRootLogin no

sudo /etc/init.d/ssh restart

run script when user login in server B(optional)

touch ~/.bash_aliases && chmod 0600 ~/.bash_aliases && $texteditor$ ~/.bash_aliases

generate ssh keys file (old)

ssh-keygen
cat ~/.ssh/id_rsa
cat ~/.ssh/id_rsa.pub

id_rsa is the private key that should never share with others.
id_rsa.pub is the public key that need to tell other severs.

already have the private key? (old)

$[texteditor]$

mkdir -p ~/.ssh && chmod 0700 ~/.ssh/ && touch ~/.ssh/id_rsa && chmod 0600 ~/.ssh/id_rsa && $texteditor$ ~/.ssh/id_rsa

then fill your private key

remote server B config public key (old)

mkdir -p ~/.ssh && chmod 0700 ~/.ssh/ && touch ~/.ssh/authorized_keys && chmod 0600 ~/.ssh/authorized_keys && $texteditor$ ~/.ssh/authorized_keys