Lab Handbook

Migrating from rsh to ssh

Because rsh and telnet are being disabled on many systems due to tightened security, one of your options is to use ssh. The reason most systems are switching to ssh is because passwords and data are encrypted.

With rlogin, it was possible to log into a remote system without using a password by setting up an .rhosts file.

With ssh, it is possible to set up such a system, but you need to generate a set of host keys. Here are the steps to do this.

Lets assume you are on a system hostx and want to be able to connect to hosty using ssh without using a password. Here's how to do it. You type the items in bold type and optional text that you may see is in italics.

On hostx, type

$ ssh-keygen -t dsa

Generating public/private dsa key pair.
Enter file in which to save the key (/home/users/username/.ssh/id_dsa): <enter>

/home/users/username/.ssh/id_dsa already exists.
Overwrite (y/n)? y

Enter passphrase (empty for no passphrase): <enter>
Enter same passphrase again: <enter>
Your identification has been saved in /home/users/username/.ssh/id_dsa.
Your public key has been saved in /home/users/username/.ssh/id_dsa.pub.
The key fingerprint is:
00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00 username@hostx

$ cat ~/.ssh/id_dsa.pub >> ~/.ssh/authorized_keys

$ chmod g-w ~/.ssh