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--- tutorials:remote_access [2011/12/13 11:14] – [SSH] mushroom
+++ tutorials:remote_access [2019/01/11 17:35] (current) – [Key] chkuo
@@ Line 18: / Line 18: @@
 ==== Key ====
-To generate key-pairs, use: <code bash>ssh-keygen -t 'rsa'</code>
+To generate key-pairs, use: <code bash>ssh-keygen -t rsa -b 4096</code>
-This command will create a pair of private key (''~/.ssh/id_rsa'') and public key (''~/.ssh/id_rsa.pub''). To enable authentication on a remote host, append the public key to the ''~/.ssh/authorized_keys'' file in the remote host.
+This command will create a pair of private key (''~/.ssh/id_rsa'') and public key (''~/.ssh/id_rsa.pub''). To enable authentication on a remote host, append the public key to the ''~/.ssh/authorized_keys'' file in the remote host (this file should be owned by the user and have the ''644'' permissions).
+If the home directory is encrypted, ''authorized_keys'' would not work while within the home directory before the user is logged in. Move the ''authorized_keys'' file and modify ''/etc/ssh/sshd_config'' accordingly.
+For example (see [[https://help.ubuntu.com/community/SSH/OpenSSH/Keys#Troubleshooting]]:
+  * set up ''/etc/ssh/<username>'' (owned by user, 755 permissions).
+  * in ''/etc/ssh/sshd_config'', add ''AuthorizedKeysFile    /etc/ssh/%u/authorized_keys''
+  * restart sshd: ''sudo service ssh restart''
+==== Keep alive ====
+To prevent the ssh sessions from being disconnected due to inactivity, add the following lines to ''/etc/ssh_config'' on the client:
+<code>
+ServerAliveInterval 60
+ServerAliveCountMax 60
+</code>
+This sends a signal every 60 seconds for a maximum of 60 times (one hour) from the client to the server.
+If you do not have the permission to make this modification, put those lines to ''~/.ssh/config'' (create the file is necessary).
@@ Line 39: / Line 55: @@
 To copy an entire directory, use: <code bash>scp -r ~/foo_dir 168.192.1.1:~</code>