ssh

Installation

apt install openssh-client openssh-server # on Debian
emerge -av net-misc/openssh # on Gentoo
pacman -S openssh # on Arch

Configuration of the ssh server

Edit the configuration file /etc/ssh/sshd_config.

Deactivate login via password

PermitRootLogin without-password
PubkeyAuthentication yes
PasswordAuthentication no

You also might want to change the port the ssh server is listening

Port <port>

You might be interested in configuring

AllowAgentForwarding yes/no
X11Forwarding yes/no

We uncommented the following lines

SyslogFacility AUTH
LogLevel INFO

LoginGraceTime 2m

StrictModes yes
MaxAuthTries 6
MaxSessions 10

HostbasedAuthentication no

IgnoreRhosts yes

PrintLastLog yes
TCPKeepAlive yes

and commented

#UsePAM yes

Manage the ssh server

The ssh server is managed via the sshd.service.

Generate ssh key pair

To generate a RSA key pair

ssh-keygen -t rsa -b 4096

To generate an eliptic curve key pair

ssh-keygen -t ed25519

Note: There is no need to set the key size, as all ed25519 keys are 256 bits.

ssh config

~/.ssh/config looks like

Host <yourNameForTheHost>
	Hostname <publicIPorDomain>
	User <user>
	Port <port>
	IdentityFile ~/.ssh/<key>

Authorized keys

Authorized keys are listed (one per line) in ~/.ssh/authorized_keys

ssh