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deb9:ssh [2022/08/14 18:38] – [Keep Alives] Bernard Condraudeb9:ssh [2025/11/08 14:09] (current) – [Settings] Bernard Condrau
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 ====== SSH Client and Server ====== ====== SSH Client and Server ======
 To login to any machine with SSH, you need to install the ssh server. The client is installed on Debian by default. Terminology used is "Server" for the remote machine to get access to, and "Host" for the local machine which needs access to a server. This guide was updated 8<sup>th</sup> August 2020. To login to any machine with SSH, you need to install the ssh server. The client is installed on Debian by default. Terminology used is "Server" for the remote machine to get access to, and "Host" for the local machine which needs access to a server. This guide was updated 8<sup>th</sup> August 2020.
 +
 +<color red>Need to update: Iapetus, Pandora</color>
  
 ===== Linux Server ===== ===== Linux Server =====
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   * Do the same for Windows Subsystem for Linux on Windows 10   * Do the same for Windows Subsystem for Linux on Windows 10
 ==== Settings ==== ==== Settings ====
-  * Modify /etc/ssh/sshd_conf:<code>Port 22+  * Modify /etc/ssh/sshd_config:<code>Port 22
 LoginGraceTime 20 LoginGraceTime 20
 AuthorizedKeysFile .ssh/authorized_keys AuthorizedKeysFile .ssh/authorized_keys
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 PrintLastLog yes PrintLastLog yes
 TCPKeepAlive yes</code> TCPKeepAlive yes</code>
-  * Restart the SSH server:<code>sudo /etc/init.d/ssh restart</code>+  * Restart the SSH server:<code>sudo service ssh restart</code>
  
 ===== Linux Host ===== ===== Linux Host =====
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     * **Save public key** and **Save private key**     * **Save public key** and **Save private key**
  
-===== Keep Alives ===== +===== Access through Relais Hosts ===== 
-I have machines in a location without fixed IP address, and where external access is only possible through a relais host which disconnects after 2+ minutes of inacitivity. I solve this by adding the following to the sshd_config of each machine which need to be accessed. +I have machines in a location without fixed IP address, and where external access is only possible through a relais host. 
-  ClientAliveInterval 300 +  * Avoid SSH disconnects after inacitivity by adding the following to ''sshd_config'' of each machine which need to be accessed.<code>ClientAliveInterval 300 
-  ClientAliveCountMax 2 +ClientAliveCountMax 2</code> 
-Alternatively, it could also be handled on the client side with the following lines in ssh_config, or keep alive setting in PuTTY.  +  * Alternatively, add the following lines to ''ssh_config'' of each client, or set the keep alive setting in PuTTY.<code>Host * 
-  Host * +  ServerAliveInterval 300 
-    ServerAliveInterval 300 +  ServerAliveCountMax 2</code> 
-    ServerAliveCountMax 2 +  * I have restricted SSH access to machines with known IP addresses, so find from where (relais machine) you connect through SSH<code>$ who</code> 
 +  * Add or modify the restriction to your ''authorized_keys'' file<code>restrict,from="aaa.bbb.ccc.ddd,eee.fff/16"</code> 
 +  * See [[deb10:backuppc|BackupPC]] how to setup a BackupPC host behind a relais host
 ==== Links ==== ==== Links ====
   * [[https://patrickmn.com/aside/how-to-keep-alive-ssh-sessions/#:~:text=On%20Linux%20(ssh)&text=These%20settings%20will%20make%20the,to%20have%20been%20discarded%20anyway.|How to Keep Alive SSH Sessions]]   * [[https://patrickmn.com/aside/how-to-keep-alive-ssh-sessions/#:~:text=On%20Linux%20(ssh)&text=These%20settings%20will%20make%20the,to%20have%20been%20discarded%20anyway.|How to Keep Alive SSH Sessions]]
   * [[https://superuser.com/questions/1272875/relay-two-ssh-connections-together|Relay two SSH connections together]]   * [[https://superuser.com/questions/1272875/relay-two-ssh-connections-together|Relay two SSH connections together]]
 +  * [[https://www.thethingsnetwork.org/docs/gateways/kerlink/reverse-ssh/|Reverse SSH]]
   * [[http://man.openbsd.org/sshd_config#:~:text=The%20client%20alive%20mechanism%20is,disconnected%20after%20approximately%2045%20seconds.|sshd_config — OpenSSH daemon configuration file]]   * [[http://man.openbsd.org/sshd_config#:~:text=The%20client%20alive%20mechanism%20is,disconnected%20after%20approximately%2045%20seconds.|sshd_config — OpenSSH daemon configuration file]]
 +===== Copy file from remote host =====
 +  * ''$ rsync -a -e "ssh -p 50922" --info=progress2 bco@192.168.1.13:/home/bco/site-backup/site*.zip /home/bco/''
 +  * [[https://linuxize.com/post/how-to-transfer-files-with-rsync-over-ssh/|How to Transfer Files with Rsync over SSH]]
 ===== X Client ===== ===== X Client =====
 ==== Debian ==== ==== Debian ====

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