SSH
Initial configuration
- Generate a keypair. Ed25519 uses Twisted Edwards curve
ss-keygen -t ed25519
- Copy generated public key to the server
ssh-copy-id -i id_ed25519 USERNAME@IP-ADDRESS
- Edit the server configuration file
/etc/ssh/sshd_config
Port 22
PasswordAuthentication no
PubkeyAuthentication yes
Disable Debian Banner
Example of returned banner
OpenSSH 7.6p1 Ubuntu 4ubuntu0.3 (Ubuntu Linux; protocol 2.0)
Use DebianBanner option in sshd_config and set it to no.
DebianBanner no
You can test the configuration for errors with sshd -t.
Result:
OpenSSH 7.6p1 (protocol 2.0)
Key verification
On your server
Check the fingerprints with the keys on your server:
for key in /etc/ssh/ssh_host_*_key; do ssh-keygen -l -f $key; done
Gitlab servers
- The website is kinda hidden: https://gitlab.com/help/instance_configuration