1. Secure services Unit-IV CHAP-1
Created By : Asst. Prof. Ashish Shah, J.M.Patel College of Commerce
Unit-IV
CHAP-1
Secure services

2. Created By : Asst. Prof. Ashish Shah, J.M.Patel College of Commerce
SECURE SERVICE
Common services, such as Telnet and FTP, were written in the days when everyone trusted everybody else on the Internet.
These services send all their traffic in plain text, including passwords.

3. Created By : Asst. Prof. Ashish Shah, J.M.Patel College of Commerce
SSH
Secure Shell, also known as SSH, is a secure Telnet replacement that encrypts all traffic, including passwords, using a public/private encryption key exchange protocol. It provides the same functionality of Telnet, plus other useful functions, such as traffic tunneling.

4. SSH into a machine for the first time ( as shown below)
Created By : Asst. Prof. Ashish Shah, J.M.Patel College of Commerce
SSH into a machine for the first time ( as shown below)
vnavrat$ ssh The authenticity of host ‘woolf.xena.edu ( )’ can’t be established. RSA key fingerprint is b2:60:c8:31:b7:6b:e3:58:3d:53:b9:af:bc:75:31:63. Are you sure you want to continue connecting (yes/no)? yes Warning: Permanently added ‘woolf.xena.edu, ’ (RSA) to the list of known hosts. password: Welcome to woolf Unauthorized usage prohibited. Please check your quotas. vnavrat:~>

5. Created By : Asst. Prof. Ashish Shah, J.M.Patel College of Commerce
SSH
SSH asks you if you want to accept and trust the host key being sent to you as being the real key.
This question is asked only once when you log in to a machine for the first time. After this first login, SSH behaves exactly like Telnet.

6. Created By : Asst. Prof. Ashish Shah, J.M.Patel College of Commerce
SSH
In addition to providing terminal access, SSH tunnels almost any other protocol through it. So, it is possible to tunnel POP, RCP, and other protocols through SSH to turn them into encrypted, more secure protocols.
Note: With enough imagination and practice, you can make almost anything more secure with SSH.

7. Created By : Asst. Prof. Ashish Shah, J.M.Patel College of Commerce
scp
Secure Copy, also known as scp, is part of the SSH package. It is a secure alternative to RCP and FTP, because, like SSH, the password is not sent over the network in plain text.
You can scp files to any machine that has an ssh daemon running.
The syntax of scp is
scp

8. Created By : Asst. Prof. Ashish Shah, J.M.Patel College of Commerce
SCP
To see an example of copying a file named camcontrol.doc to remote host main from local host terry
~]$ scp camcontrol.doc
password:
camcontrol.doc 100% 117KB 117.0KB/s 00:00

9. Created By : Asst. Prof. Ashish Shah, J.M.Patel College of Commerce
sftp
Secure File Transfer Program, also known as sftp, is an FTP client that performs all its functions over SSH.
The syntax for sftp is: sftp file
Following shows copying the file tcres.pdf from the remote PC main to the localPC.
~]$ sftp tcres.pdf
Connecting to main...
password:
Fetching /home/terry/tcres.pdf to tcres.pdf
/home/terry/tcres.pdf 100% 222KB 73.9KB/s 00:03

10. Created By : Asst. Prof. Ashish Shah, J.M.Patel College of Commerce
Less Secure Services
These are nonsecure services that should not be used, since they trust that the network is absolutely secure. Their secure equivalents should be used instead.

11. Created By : Asst. Prof. Ashish Shah, J.M.Patel College of Commerce
Telnet
Telnet is a protocol and application that enables someone to have access to a virtual terminal on a remote host.
It resembles text-based console access on a
UNIX machine.
Telnet is an application that’s available almost everywhere. Because of this distribution, most beginning UNIX users use Telnet exclusively to communicate with other UNIX and NT machines

12. Created By : Asst. Prof. Ashish Shah, J.M.Patel College of Commerce
Telnet
Since all Telnet traffic, including passwords, is sent in plain text, the Secure Shell (ssh) command should be used instead, if at all possible.
SSH provides an equivalent interface to Telnet, with increased features, and most importantly, encrypted traffic and passwords.
This is what it looks like when you log into a machine with Telnet:
~]$ telnet terry
Trying
Connected to xena.
Escape character is ‘^]’.
Welcome to terry.muhlenberg.edu
login:

13. Created By : Asst. Prof. Ashish Shah, J.M.Patel College of Commerce
FTP
FTP is a common file transfer protocol that runs over ports 20 and 21. For transferring software packages from anonymous FTP repositories, FTP is still the standard application to use.
scp encrypts the traffic, including passwords. Once you have successfully logged on to an FTP server, you can type help for a list of available commands.

14. Created By : Asst. Prof. Ashish Shah, J.M.Patel College of Commerce
Two important commands to remember are put to move a file from your machine to the remote machine, and get to pull a file from the remote server to your machine.
To send multiple files you can use mput, and to retrieve multiple files you can use mget. ls or dir gives you a listing of files available for downloading from the remote site.

15. Created By : Asst. Prof. Ashish Shah, J.M.Patel College of Commerce
rsync
rsync is an unencrypted file transfer program that is similar to RCP. It includes the added feature of allowing just the differences between two sets of files on two machines to be transferred across the network.
Because it sends traffic unencrypted, it should be tunneled through SSH.

16. Created By : Asst. Prof. Ashish Shah, J.M.Patel College of Commerce
rsh
rsh is an unencrypted mechanism for executing commands on remote hosts.
Normally you specify a command to be run on the remote host on rsh’s command line, but if no command is given, you are logged into the remote host using rlogin.
rsh’s syntax is
rsh remotehostname remotecommand

17. Created By : Asst. Prof. Ashish Shah, J.M.Patel College of Commerce
rlogin
rlogin is a remote login program that connects your terminal to a remote machine’s terminal. rlogin is an nonsecure protocol, because it sends all information,including passwords, in plain text.
It also enables an implicit trust relationship to exist between machines, so that you can use rlogin without a password.

18. Created By : Asst. Prof. Ashish Shah, J.M.Patel College of Commerce
finger
finger enables users on remote systems to look up information about users on
another system. Generally finger displays a user’s login name, real name, terminal
name, idle time, login time, office location, and phone number.