Chapter 10 SSH

Question 2

What does SSH stand for?

Answer 2

Secure Shell

SSH allows you to log into a remote system securely.

Question 3

What service must be running on the remote system for SSH to work?

Answer 3

sshd

You issue a command from your workstation to connect to the remote system.

Question 4

To connect to a remote system called serverb, what command would you use?

Answer 4

$ssh serverb

You will be asked for the password of the account.

Question 5

How do you log out of a remote system using SSH?

Answer 5

Type ‘exit’

This command ends the SSH session.

Question 6

What command can you run on serverb without logging in?

Answer 6

$ssh serverb who

This command retrieves information about users currently logged in.

Question 7

True or false: SSH is a secure tunnel between client and server.

Answer 7

TRUE

The communication is encrypted using keys.

Question 8

What command is used to generate SSH keys?

Answer 8

$ssh-keygen

This command creates a private and public key pair.

Question 9

Where is the private key created?

Answer 9

~/.ssh/id_rsa

The private key must have permission of 600.

Question 10

Where is the public key created?

Answer 10

~/.ssh/id_rsa.pub

The public key must have permission of 644.

Question 11

What command do you use to copy the public key to the server?

Answer 11

$ssh-copy-id studentb@serverb

This command allows for key-based authentication.

Question 12

What is the configuration file for OpenSSH?

Answer 12

/etc/ssh/sshd_config

This file contains settings for the SSH daemon.

Question 13

How do you prohibit root from SSH logins?

Answer 13

Change ‘PermitRootLogin yes’ to ‘PermitRootLogin no’

This is a major security concern.

Question 14

What must you change to prohibit passwords from SSH logins?

Answer 14

Change ‘PasswordAuthentication yes’ to ‘PasswordAuthentication no’

This forces public key authentication.