Use ssh with private key public key authentication. Connect from wan.

procedure

Operation on the client

Make a key with PuTTygen on the client side. If you don't have PuTTygen, please install PuTTy.

Operation on the server

Format the public key you sent into a format that can be used by the server.

$ ssh-keygen -i -f key name.pub >> authorized_keys

Create a .ssh directory in / home / user name.

$ mkdir /home/user name/.ssh

Move the formatted public key to .ssh.

$ mv authorized_keys /home/user name/.ssh

Set access privileges for authorized_keys.

$ chmod 600 .ssh/authorized_keys

Set access rights for .ssh.

$ chmod 700 .ssh

With the above settings, you can now ssh connect using the key authentication method. From here, for added security, change the server settings to prevent password authentication and change the port.

Operation on the server

Open the ssh configuration file in an editor.

$sudo vim /etc/ssh/sshd_config

Disable password authentication.

PasswordAuthentication no

Change the port number in sshd_config.

#Port22
Port2000

Restart sshd

$service sshd restart

This completes the settings. When connecting from wan, use the port forwarding function of the router.

Log in from the client using the private key from PuTTy. For the private key, specify the path from the Auth field in the SSH of Category: Connection.

Where it gets stuck

I didn't realize I had to format my public key on linux and took a long time to set it up.

Reference site

Summary of procedure for making SSH connection with public key authentication method with PuTTY