FreeBSD 14
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OpenSSH : SSH Key-Pair Authentication2023/12/19

Configure SSH server to login with Key-Pair Authentication.
Create a private key for client and a public key for server to do it.
[1] Create Key-Pair by each user, so login with a common user on SSH Server Host and work like follows.
# create key-pair

freebsd@dlp:~ $

Generating public/private rsa key pair.
Enter file in which to save the key (/home/freebsd/.ssh/id_rsa):   # Enter or input changes if you want
Enter passphrase (empty for no passphrase):   # set passphrase (if set no passphrase, Enter with empty)
Enter same passphrase again:
Your identification has been saved in /home/freebsd/.ssh/id_rsa
Your public key has been saved in /home/freebsd/.ssh/
The key fingerprint is:
The key's randomart image is:

freebsd@dlp:~ $
ls -l ~/.ssh

total 18
-rw-------  1 freebsd freebsd 2655 Dec 19 10:36 id_rsa
-rw-r--r--  1 freebsd freebsd  575 Dec 19 10:36
-rw-------  1 freebsd freebsd  846 Dec 19 10:12 known_hosts
-rw-r--r--  1 freebsd freebsd   98 Dec 19 10:12 known_hosts.old

freebsd@dlp:~ $
mv ~/.ssh/ ~/.ssh/authorized_keys

[2] Transfer the private key created on the Server to a Client, then it's possible to login with Key-Pair authentication.
freebsd@node01:~ $
mkdir ~/.ssh

freebsd@node01:~ $
chmod 700 ~/.ssh
# transfer the private key to the local ssh directory

freebsd@node01:~ $
scp ~/.ssh/

( Password for
id_rsa         100% 2655     2.8MB/s   00:00

freebsd@node01:~ $

Enter passphrase for key '/home/freebsd/.ssh/id_rsa':   # passphrase if you set
Last login: Tue Dec 19 10:01:15 2023 from
FreeBSD 14.0-RELEASE (GENERIC) #0 releng/14.0-n265380-f9716eee8ab4: Fri Nov 10 05:57:23 UTC 2023

Welcome to FreeBSD!

freebsd@dlp:~ $     # logined
[3] If you set [PasswordAuthentication no], it's more secure.
root@dlp:~ #
vi /etc/ssh/sshd_config
# line 61 : uncomment

PasswordAuthentication no
# line 65 : uncomment and change

root@dlp:~ #
service sshd restart

SSH Key-Pair Authentication on Windows Client #1
This is the example to login to SSH server from Windows Client.
On this example, it shows with Putty.
Before it, Transfer a private key to Windows client computer.
[4] Run [Puttygen.exe] that is included in [Putty]. (placed in the folder [Putty.exe] is also placed)
If not included, Download it from official site (
After starting [Puttygen.exe], Click [Load] button on the following window.
[5] Specify the private key that you transferred from SSH server, then passphrase is required like follows, answer it. (if not set passphrase, this step is skipped)
[6] Click [Save private key] button to save it under a folder you like with any file name you like.
[7] Start Putty and Open [Connection] - [SSH] - [Auth] - [Credencials] on the left pane, then specify your private key on the [Private key file] field.
[8] Back to the [Session] on the left pane and specify your SSH server host to Connect.
[9] When SSH key-pair is set, the passphrase if it is set is required to login like follows, then answer it.
SSH Key-Pair Authentication on Windows #2
[10] OpenSSH Client has been implemented as an Windows feature, so it's possible to authenticate with SSH Key-Pair without Putty and other 3rd party softwares. Transfer your private key to your Windows and put it under the [(logon user home).ssh] folder like follows, then it's ready to use Key-Pair authentication.
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