Conas a shuiteáil agus a chumrú freastalaí SSH ar Debian Linux?

Shuiteáil agus a thástáil an Freastalaí SSH

You will need to be root to do the following…

su

1. Suiteáil Freastalaí SSH

   apt install openssh-server
    

2. Seiceáil más ann an bpróiseas freastalaí. Léiríonn sé seo an Chuaigh shuiteáil maith.

   ps -A | grep sshd

   aschur (nó a leithéid): 1753 ? 00:00:00 sshd

    

3. Suiteáil Cliant SSH a sheiceáil leis an nasc SSH Freastalaí

   apt install openssh-client

   Ceangail le localhost nasc a thástáil

   ssh localhost

   Chomh maith leis sin logáil isteach leis an seoladh IP comhéadan

   Faigh IP Seoladh

   ip addr

   SSH ar an seoladh IP

   ssh {ipaddress here}
    

Securing the SSH Server

It is a good idea to secure the SSH server by disallowing root to login and configuring login only by public key i.e. login using passwords is not allowed

Ensure to execute the following commands as your user and not as root

1. Navigate to the user home directory

   cd
    

2. Seiceáil an bhfuil .ssh

   ls -a
    

3. Más rud é nach bhfuil .ssh ann, chruthú

   mkdir .ssh
    

4. Socraigh an cead fhillteáin 700

   chmod 700 .ssh
    

5. Create the authorized_keys file

   touch ./.ssh/authorized_keys
    

6. Change permission on the authorized_keys file to 600

   chmod 600 ./.ssh/authorized_keys
    

7. Open the authorized_keys file

   nano ./.ssh/authorized_keys
    

8. Paste your public key into the file

   You can get your public key from the SSH client. If the client is Windows 10 then it will be in the %USERPROFILE%/.ssh/id_rsa.pub file. If the client is Debian then the public key is ~/.ssh/id_rsa.pub.

   If your public key does not exist, generate it on the client machine

   ssh-keygen -t rsa -C "email@domain.com"
    

9. Change to root user

   su

10. Configure your SSH server to accept only public key logins and prevent login for root

    nano /etc/ssh/sshd_config

    Uncomment and/or edit the following lines

    PermitRootLogin no
StrictModes yes
PubkeyAuthentication yes
AuthorizedKeysFile .ssh/authorized_keys .ssh/authorized_keys2
PasswordAuthentication no
     

11. Restart the sshd service

    service sshd restart
     

12. Try logging in as root from your SSH client using password

    ssh root@{ssh server ip address}

    aschur: Permission denied (publickey).

     

13. Try logging in as username from your SSH client using password

    ssh username@{ssh server ip address}

    aschur: Permission denied (publickey).

     

14. Try logging in as root from your SSH client using the public key

    ssh root@{ssh server ip address} -i .ssh/id_rsa

    aschur: Permission denied (publickey).

     

15. Log in as username from your SSH client using the public key

    ssh username@{ssh server ip address} -i .ssh/id_rsa
     

If your SSH client has a static IP address then you may want to consider only your IP address can login to the SSH server.