This is my first entry on this blog, and I will discuss to you my experiences and learning for our activity today.
For today's laboratory class, Sir Joman introduced to us Data Communications and Networking.
First, he discussed about Security Shell (SSH) and SSH Security. Here is a definition of Security Shell: a cryptographic network protocol for secure data communication, remote command-line login, remote command execution, and other secure network services between to networked computer. I also learned from him and from the handout given that there are to ways to secure SSH, one is the traditional username-password combination, the other one is the public-private keys.
After the discussion, he asked us to do our exercise. Here are the things that I have learned from it:
Adding a user on local computer
To add a user on local computer,type sudo adduser <username> on terminal. Then, provide password and some information for that username.
Logging in to a remote computer (server) via SSH using username-password combination
You do this, you must first log in your account ($su <username>). Out teacher provided a username and password to be used to connect to a remote computer using ssh. To do this, type ssh <username>@<IPAdressOfServer>
Configuring local computer for a passwordless login (public key cryptography)
First, logout from the remote computer ($exit), then go to your local computer's home directory under your home folder and go to that directory. Execute the following command to login to a remote computer without using a password:
$ssh-keygen -t rsa
$<enter>
$<enter>
$<enter>
First, logout from the remote computer ($exit), then go to your local computer's home directory under your home folder and go to that directory. Execute the following command to login to a remote computer without using a password:
$ssh-keygen -t rsa
$<enter>
$<enter>
$<enter>
Execute $ssh-copy-id username@IPAddressOfServer and log in again to the remote server using your username: $ssh username@<IPAddressOfServer>
Broadcasting a message to other connected users to the remote computer
This is done using wall (write to all). First, make sure that your mesg is set to yes. Then, use any of the following command to broadcast message:
$wall <<< "<message>"
$echo "<message>" | wall
$wall <file name]
To terminate wall, type Ctrl+D.
Sending a message to a particular user only
This is done using write ($write <username-of-the-other-user> [enter]). Write your message after. To reply, make sure you first initiated the write program to the user who is writing to you (do the write command). Type Ctrl+D to end the conversation.
Additional information:
After setting up passwordless login in your workstation to the remote computer, if you log in to the remote server using different workstation, it would not be passwordless anymore because you need configure again your current workstation to the remote computer.
This is done using write ($write <username-of-the-other-user> [enter]). Write your message after. To reply, make sure you first initiated the write program to the user who is writing to you (do the write command). Type Ctrl+D to end the conversation.
Additional information:
After setting up passwordless login in your workstation to the remote computer, if you log in to the remote server using different workstation, it would not be passwordless anymore because you need configure again your current workstation to the remote computer.
