Institute of Telecommunications
Faculty of Electronics and Information Technology
Warsaw University of Technology, March 2015
EINTE LAB EXERCISES
LAB EXERCISE #2 – EMAIL SERVICE
PREPARATIONS
REMOTE SESSION
Before starting the exercise, please familiarize yourself with the documents related to remote access to
lab facilities (Remote Access User Guide) and lab resource reservation system (Resource Reservation User
Guide).
Before connecting to the remote virtual machine please make sure that Remote Desktop is
configured such that it is possible to transfer files from the virtual machine to a local
drive (appropriate local resources are attached in the connection options of the remote desktop
session). It is necessary to transfer files (eg. Wireshark application logs) required to be attached to the
final report.
Do not manually change anything in the network configuration of the host that has been assigned
to you to execute the exercise as it may lead to disturbances in lab infrastructure setup. Do not attempt
this lab exercise with a “trial-and-error” approach – it will not work! Prepare by reading and
understanding the course materials and RFCs listed in the next section.
EMAIL BASICS
You should familiarize yourself with the protocols used to implement the Internet email service:
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POP3 ( http://tools.ietf.org/html/rfc1939 )
IMAP ( http://tools.ietf.org/html/rfc3501 )
SMTP ( http://tools.ietf.org/html/rfc2821 ).
During the exercise you will need a basic knowledge of the above protocols. The RFCs above contain
also useful information to answer questions required in the report. However, there is no need to read all
these documents in full.
The following example of the Simple Mail Transfer Protocol session can be helpful in executing the
exercise.
Institute of Telecommunications
Faculty of Electronics and Information Technology
Warsaw University of Technology, March 2015
NETSH
Netsh command allows viewing and modifying a network configuration of the host. This command is
invoked from the command line in Windows. Please review (briefly) the documentation for the
command available at:
http://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/enus/netsh.mspx?mfr=true
In particular, pay attention to the commands used to configure the TCP/IP protocols.
TELNET
Telnet client application is available from the Windows command line. It will be used for sending and
receiving the email access protocol messages to the mail server. You should become familiar with the
capabilities of the telnet application. To do this, run the application from the Windows command line
with the /? parameter.
STEP 1: SET THE DNS SERVER ADDRESS
Using netsh add a new DNS server and set it as the primary server. The DNS server IP address is
194.29.169.68. To do this, first open the Windows command line terminal (on Windows 7 you need to
run it with elevated permissions – “run as administrator”). Start by checking the network name with:
netsh interface show interface
It will show the name under the "Interface Name" column. If the output is empty, you can always check
the interface name in Control Panel, under “Network Connections” (“Network and Sharing Center” in
Windows 7). Then you can change the primary dns (index=1). Assuming that your network name is
“Local Area Connection”, the netsh command should look like:
in Win7: netsh interface ipv4 add dnsserver "Local Area Connection" address=194.29.169.68 index=1
in WinXP: netsh interface ip add dns “"Local Area Connection" 194.29.169.68 index=1
Institute of Telecommunications
Faculty of Electronics and Information Technology
Warsaw University of Technology, March 2015
Note: do not use the Windows GUI to change anything in the network configuration of the host!
Note: When performing the next tasks, please pay attention to the context of communication with the
above address using the DNS protocol. The report should describe the course and purpose of this
communication; please also attach the relevant WireShark files to the report.
STEP 2: SEND THE FIRST MESSA GE
Based on the SMTP session example, use telnet to send the first message. To compose a message, use
the following parameters:
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From: <hostname>@ ztit.lab.org (replace <hostname> with the corresponding value
obtained by executing ipconfig / all command)
To: lab3@ztit.lab.org
Subject: LAB3
Body: login: <username> (where <username> is the username used to log to ztit-gateway).
Please note the space after “:” sign and be aware of uppercase and lowercase letters.
Next, use telnet to connect to ztit.lab.org server. Communication should use the standard SMTP port
number. The report should contain the information obtained from the console when sending messages
and the relevant WireShark logs.
STEP 3: RETRIEVE AN E-MAIL
Using information from the RFCs mentioned at the beginning of the document and information
available on the Internet, retrieve email messages from the mailbox. Two messages with the following
subjects will be available for retrieval: "LAB3-IMAP" and "LAB3-POP". The first message should be
retrieved using IMAP, the second using POP3, for both operations you should use telnet application.
The mailbox is located at ztit.lab.org; to connect via POP3 and IMAP, use standard port numbers; the
user name is the same as the previously used host name; password is the same as the password for the
host used during the exercise.
Note: message retrieval is only possible when the message from step 2 has been sent correctly.
STEP 4: VERIFICATION
Using telnet send a message similar as in step 2, but with different Subject and Body. The new Subject
is ANSWER (in capital letters), the new text of the message should look as follows:
login: <username>
answer: <POP3><IMAP>
Please note the space after “:” and be aware of uppercase and lowercase letters.
Username is the same as in step 2, <POP> and <IMAP> should be replaced by the content of the
respective messages retrieved in step 3, concatenated without any space.
If a message is properly constructed and sent in the correct way, the new message with the Subject:
RESULT will be sent to the previously used mailbox as a confirmation. You should retrieve this message
using the protocol of choice. The report should contain the content of a confirmation message, together
with the relevant WireShark logs.
Institute of Telecommunications
Faculty of Electronics and Information Technology
Warsaw University of Technology, March 2015
THE REPORT
You need to prepare a document (in PDF format) containing the description of the course of the
exercise, observations and conclusions on the types of messages in the network (i.e. explain what types
of messages, when and in what order were sent). You should attach the relevant WireShark logs (in
.pcap format) to the report as well as any files mentioned earlier as required.
The report should also contain the short answers to the following questions.
1. How data is transmitted over telnet protocol and what is the danger associated with it?
2. What is the most popular usage of the telnet protocol? What protocol is used as a secure
alternative to telnet?
3. What is the difference between POP3 and IMAP?
4. What is the difference between POP3 and POP3S, IMAP and IMAPS?