Mengamankan SSH dengan Public Key Authentication

Creating the Key Pair

Kunci SSH digunakan untuk mengautentikasi komputer saat terhubung ke server. Kunci SSH memberikan tingkat keamanan yang tinggi tanpa menggunakan kata sandi dan memungkinkan manajemen akses yang lebih efisien.

ssh-keygen

Output
Generating public/private rsa key pair.
Enter file in which to save the key (/your_home/.ssh/id_rsa):

Output
Your identification has been saved in /your_home/.ssh/id_rsa
Your public key has been saved in /your_home/.ssh/id_rsa.pub
The key fingerprint is:
SHA256:/hk7MJ5n5aiqdfTVUZr+2Qt+qCiS7BIm5Iv0dxrc3ks user@host
The key's randomart image is:
+---[RSA 3072]----+
|                .|
|               + |
|              +  |
| .           o . |
|o       S   . o  |
| + o. .oo. ..  .o|
|o = oooooEo+ ...o|
|.. o *o+=.*+o....|
|    =+=ooB=o.... |
+----[SHA256]-----+

Copying the Public Key to Your Ubuntu Server

Copying the Public Key Manually

cat ~/.ssh/id_rsa.pub

Output
ssh-rsa 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 demo@test

login ke server dan copy yang tadi dan paste ke directory server

~/.ssh/authorized_keys

jika tidak ada file authorized_keys di server buat dengan touch

touch ~/.ssh/authorized_keys

sudo nano ~/.ssh/authorized_keys

Disabling Password Authentication on Your Server

mematikan login dengan password

sudo nano /etc/ssh/sshd_config

Inside the file, search for a directive called PasswordAuthentication. This line may be commented out with a # at the beginning of the line. Uncomment the line by removing the #, and set the value to no. This will disable your ability to log in via SSH using account passwords:

/etc/ssh/sshd_config
. . .
PasswordAuthentication no
PubkeyAuthentication yes
PermitRootLogin no
. . .

sudo systemctl restart ssh

ssh username@remote_host

contoh

contoh user nakal yang mencoba login ke server yang mengetahui username, password dan ip server tetapi tidak memiliki private key server

contoh user yang memiliki private key dan publik key nya sudah di masukan ke server bisa langsung login tanpa password karena menggunakan kunci private-key