7COM1012 Report: Secure Shell Protocol, Authentication, and Security

This report provides a comprehensive analysis of the Secure Shell (SSH) protocol, examining its role in network security and remote access. The report begins with an introduction to SSH, followed by a review of its history and literature. It then delves into the core functionalities of SSH, including its working mechanism, authentication methods, and security features such as encryption and data integrity. The report also explores the scope and limitations of SSH, including user authentication, password authentication, and the prevention of IP source routing and DNS spoofing. Furthermore, it details the methods used in SSH, such as its major components and controls over access and port forwarding. An experiment section analyzes the evolution of SSH, including the advantages of SSH key authentication and the generation of SSH keys. The report concludes with a summary of the key findings and the importance of SSH in securing network communications. This document is a student's assignment and is available on Desklib, a platform offering AI-based study tools.

Running head: SECURE SHELL
Secure Shell
Name of the Student
Name of the University
Author Note

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Abstract
Secure Shell offers Associate gives the open protocol customer/server arrangements provides
command shell, document move along with administration of data burrowing for the applications
of TCP/IP. Encryption, data integrity and secure authentication is provided by the connections of
SSH for battling with the dangers related with elective security and watchword stealing in an
amazing manner. This particular discipline of engineering along with the assistance of the
respective layers of it which are inbuilt. In addition to this, those layers which are inbuilt within
it are independent of each other. Integrity, confidentiality and client authentication is provided by
it. It provides with end-to-end delivery which is connection – oriented and encoded burrow are
multiplexed into several coherent channels. The datagram gets delivered over multiple systems
by it which might provide compression alternatively.

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Table of Contents
1. INTRODUCTION...................................................................................................................5
2. HISTORY AND LITERATURE REVIEW............................................................................6
2.1. Working of SSH................................................................................................................7
2.2. Scope and limitations........................................................................................................8
2.2.1. User-Authentication...................................................................................................8
2.2.3. Prevents IP source routing.........................................................................................9
2.2.4. Keeps the users safe from DNS Spoofing.................................................................9
2.2.5. Data manipulation through the network at networks could not be done...................9
2.2.6. Spoofing of IP address...............................................................................................9
2.2.7. Easy management of a dedicated server remotely...................................................10
3. METHODS............................................................................................................................10
3.2 Need for SSH.......................................................................................................................11
3.3 Major components of SSH...................................................................................................11
3.5.4. Controls over Access...................................................................................................14
3.5.5. Forwarding in ports......................................................................................................15
3.5.6. Secure and remote execution of commands................................................................15
4. EXPERIMENT: ANALYSIS AND EVOLUTION..............................................................16
5. Development of SSH.............................................................................................................23
5.2. Advantages of SSH Key Authentication............................................................................24

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5.3. Generation of SSH keys......................................................................................................25
5.4. SSH Key Access.................................................................................................................25
6. CONCLUSION..........................................................................................................................25

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1. INTRODUCTION
As internet access turns out to be increasingly available and economical, it has additionally
turned out to be a feasible replacement for fax, telephone and traditional couriers along with the
accessibility of the remote dial-ups to the internal electronics assets of the company. Probably,
the greatest challenge in utilization of the internet for replacing the traditional communications in
a progressive manner is a security. Previously, various kinds of companies have tried to maintain
their respective modern bank accessibility of dial-up to the assets of the company. They have
tried to maintain it with the aim of not transmitting of the critical data with the utilization of
public network (Barrett et al. 2001). On the other hand, modern banks are expensive to maintain
and also do not scale up. The charges of long-distances for the warrior alone are enough for
making up of this expensive arrangement in the large companies. Secure Shell is basically a
protocol which is accountable for providing data integrity, encryption and authentication for
securing the connections of network.
Several kinds of accompanying categories like that of a secure record transfer, a secure
command shell along with remote access of various application of TCP/IP through a secured
passage is offered by the implementation of the Secure Shell. Both the customers of the Secure
Shell along with the applications of the server are widely present for most of the popular
frameworks which are utilized for operation.
There are numerous procedures for utilizing SSH. One of the procedure comprises of utilization
of the pairs of private-public key which gets generated in an automatic manner. This is utilized
for the encryption of the connection of the network along with the utilization of password

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authentication for signing on. The other procedure of the utilization of SSH involves the
utilization of the pairs of the public-private key which gets generated manually. This is utilized
for playing out of the authentication by allowing the clients for signing in without the occurrence
of the determination of the passwords. In this context, a matching pair of several keys could be
created by anyone. The pairs of keys which would be created could be both private and public as
well. The public key gets placed on all the personal computers which allow the accessibility of
the proprietor for matching of the private key during the proprietor remains discrete.
The real authentication occurs on the basis of the private key as the key itself never gets
transferred via the network at the time of authentication. It is confirmed by SSH that whether or
not the private key is owned by the same individual possessing the public key. It is important to
have the confirmation that all the public keys along with the several associated public keys are
obscure with the private key personalities. It should be confirmed before the acceptance of them
that they are valid or not. The reason behind this is that an unauthorized attacker could get
authorized in the form of a valid client if the validation of the public key does not get validated.
2. HISTORY AND LITERATURE REVIEW
A steady improvement as well as increment in the adoption has been witnessed by Secure Shell
since 1995. The initial variant of the Secure Shell which is SSH1 was planned for replacing of
UNIX “r-command” like that of rsh, rcp and rlogin etc. which is not very secure naturally. The
second version of Secure Shell was submitted in the form of IETF draft in the year 1997. This

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help in addressing of the part of certain severe vulnerabilities within SSH1. This also helps in
providing the arrangement of record transfer in an improved manner. This particular
improvement in the popularity has already been enlivened by the wider availability of the
applications of server and clients which are supported and were created on a commercial basis.
The applications of server and client were created for UNIX, Windows and several other
platforms. This also included the endeavours of the tasks of the open SSH for building up of the
implementation of the open-source.
2.1. Working of SSH
It gets executed by the verification and exchange of the information by the utilization of both
private and public keys for differentiating between users and hosts. It provides the encryption of
the resulting communication by the utilization of the cryptography of private/public key. Client
gets suggested to any PC or any workstation which the client has already signed in. For example,
this comprises of the respective workstation of the users or gathering of the workstation which
provides the management of the XDM sessions to several other X terminals. The term “severs”
indicates towards a secondary workstation which is remote and are wished by the clients for
singing in for doing some kind of work (Garimella and Kumar 2015). Various examples of this
comprises of a server of login session. The client forms the place where the “rcp document
server: “new file” or “rlogin server” is typed in. On the other hand, server forms the place where
the other session of login is received by the users. The duplicating records or the brief of the
shell is also received by the users in this particular place. A personality could be generated by
the users in the client systems by the procedure of running of the program of ssh-keygen. A
subdirectory known as $HOME/.ssh is created by this type of programs. This is responsible for

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embedding in two records which are named by the character along with identity.pub which
comprises of the private and public of the users for the account of the users on the client system.
The record of the latter then gets appended into a document named as $HOME/.ssh/authorized
keys which remains present on all of the servers where the SSH connections would be made. A
private and a public key is generated by the system administrator for the system. With the
utilization of the contained information within the system, the possibility of spoofing of the
character of the system by the process of faking of IP addresses or robbing up of the DNS
records by which the domain names and IP address gets associated gets expelled.
2.2. Scope and limitations
2.2.1. User-Authentication
Authentication is the medium by which any system could confirm that accessibility is just
provided to the authorized users and are denied to the unauthorized users. The secure
implementation of Secure Shell involves the incorporation of several authentication strategies
of public key and password. The advanced strategies of authentication are allowed by the
adaptability of the protocol of Secure Shell to be absorbed within the system according to
their availability.
2.2.2 Password Authentication
Passwords and usernames are a particular method for the authentication a user. Protocols like
telnet showcases both username and passwords in a clear manner because the content of ASCII
are making them insecure. Be that as it may, it is made sure by the Secure Shell protocol that all
the usernames along with the passwords are encrypted before they get passed onto the network.

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The mechanism of the authentication of the username and password expect eavesdropping by the
attackers by whom the important data could be trapped.
2.2.3. Prevents IP source routing
Source routing is basically utilized for several good purposes like alteration of the network signal
path in the event that it gets failed originally, it could also be utilized by the malicious users for
making the machine think that it is communicating with the alternate one. The malicious
utilization of the routing of the IP source could be avoided by the utilization of secure shell.
2.2.4. Keeps the users safe from DNS Spoofing
In this type of hacking attack, data gets embedded within the Domain Name System name in the
cache database of the server. This enables the name server in restoring an incorrect IP address
such that it could redirect the traffic to the other way. This takes place form the PC of the
attacker and from that place important information could be obtained. The possibilities of IP
address redirection becomes less with the utilization of encryption of the secure shell.
2.2.5. Data manipulation through the network at networks could not be
done
Data could be changed or obtained by the attacker through the course of the network at the
intermediaries. This is frequently performed at the routers where data enters a checkpoint or
gateway during its transit to its respective destination. Data appears in the form of random
characters as it is encrypted. For this purpose, data tracking by the gate crashers would become
troublesome.

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2.2.6. Spoofing of IP address
IP spoofing is that where packets are created with a produced IP address of the source by the
malicious users. So, the location and personality of the PC remains a mystery and this appears to
be the other PC which in turn is trusted by the recipients. The data packets are kept by the public
key from being forwarded to a destination which is off- base despite the fashionable packets.
2.2.7. Easy management of a dedicated server remotely
The users could manage the monitoring of logs, remote dedicated server, manipulate databases,
stop and start the benefits and install several applications with the utilization of SSH. Normal
UNIX commands are perceived by SSH which could be utilized for login in the form of root for
the full administration of the system as it is the most secured and reliable method for managing
the server.
2.2.8 Limitations
2. No forwarding of dynamic ports and port ranges.
3. The forwarding of the ports could not be limited for every user. The RSA character of the
client is not checked against the known hosts of SSH when the users obtains authentication
by the password.
4. Lower level of performance on the old machines.
5. The defaults of the conveyances of standard SSH1 incorporates a clear alternative of the
book or those patented algorithms.
6. Prohibition of the licensing of the original source.

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3. METHODS
3.1 Overview
SSH Secure Shell is a command interface which is based on UNIX. It is a protocol of
cryptographic network which is utilized for ensuring data in transmission among the gadgets.
This gadget provides with solid authentication and a secure channel gets established over a
network which is insecure.
3.2 Need for SSH
The development of internet led to increment in the number of threats which comprises of
connection hijacking, DNS spoofing, network monitoring and denial of the attacks of
administration. The transfer of the documents along with remote execution of the command and
remote logins became conceivable with the support of the several protocols like telnet, tcp and
ftp as well. It becomes easy for the gate crasher in reading and blocking the data.
3.3 Major components of SSH
Data integrity, data confidentiality, server authentication is provided by transport layer protocol
which might optionally provide compression. The user authentication protocol helps the user in
authenticating the users to the respective server. The connection protocol helps in multiplexing
of numerous communication channels which are logical over the hidden connection of the
connection of SSH.
3.3.1. Transport Layer Protocol

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Authentication of a server takes place at this particular layer on the basis of the server containing
the pair of private-public key. The server contains the key which is utilized at the time of the
exchange of the key for the authentication of the host character.
3.3.2. User Authentication protocol
This particular protocol provides with a medium with which the client gets authenticated with the
server. Three types of messages are utilized by this protocol. The format of authentication
comprises of
Byte SSH_MSG_USERAUTH_REQUEST (50)
String Username
String Service name
String Method name
… Method specific fields
Byte SSH_MSG_USERAUTH_FAILURE(52)
Name-list Authentications that can continue
Boolean Partial Success
3.3.3. Connection Protocol
The connection protocol of SSH operates on the top of the Transport Layer Protocol of SSH.
The utilization of secure connection of authentication is assumed by this connection protocol.
The secure connection of authentication is utilized by this protocol for multiplexing a huge

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number of logical channels. This protocol also operates on the top of the user authentication
protocol. A terminal session too is supported by the utilization of separate channels.
Byte SSH_MESSAGE_CHANNEL_OPEN String Channel Type
Unit 32 Sender Channel
Unit 32 Initial Window Size
Unit 32 Maximum Packet Size
3.4 Secure Shell Authentication
The integrity and coding of SSH guarantee the characters as well as keep the knowledge safe.
The authentication of the user is frequently marked as the user character and recommends that
the accessibility of the system is provided to the mean users and are denied to everybody other
than them. Several strategies of authentication comprises of security mechanisms which would
work along with the written password of the acquired type. This involves the authentication of
the hosts along with encryption along with the integrity of data.
3.5 SSH Features
3.5.1. Secure Remote Login
Imagine you possess an account on any other PC which needs to be interfaced from the home PC
to any ISP along with the utilization of program of telnet for signing into the accounts on the
other PCs. The entire process of sign in remains unmistakable and such issues of security is
countered by SSH. The users get authenticated by the client to the nearby PCs with the
utilization of encryption connection of SSH (Ylonen and Lonvick 2006). This indicates that both
password and the username have already been encrypted before leaving the local machine. The

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user then gets logged in by the server of SSH and the entire session of login gets encrypted as
and when it gets transferred between the server and the client as well.
3.5.2. Secure File Transfer
Assuming that two accounts are held by you on the internet. The user wants to send a file from
one PC to the other. The file which needs to be transferred comprises of sensitive and
confidential information which should only be accessed by the authorized persons. Under these
kinds of circumstances, a command could be utilized for transferring of all the files in a secure
manner among the machines with the utilization of duplicate command which is secured. This
duplicate command in turn helps in the process of encryption of the file because it leaves as well
as decodes at the destination only.
$ SCP my_file [e-mail];
3.5.3. Keys and agents
Remembering of passwords is a difficult task. There are higher chances of making of mistakes
takes place due to higher number of attempts which is also an issue of security. A mechanism is
provided by SSH for countering this particular scenario. All of the accounts of the users could be
recognized by them by the method of typing of the passwords in a continual manner. Keys are
utilized as compared to passwords. The process comprises of:
 Placing of the special files called as files of the public key with the accounts of the
remote PC.
 The ssh-agent program needs to be invokes that operates in the background on the local
machine.
 The key needs to be selected at the time of the login session.

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 Loading of the keys with the program of the ssh-agent which demands the mystery
passphrase knowledge.
3.5.4. Controls over Access
Assuming you are wishing another person have access to your account but only for specific
situations. As an example, if you're outside and you'd prefer a friend reads your emails but not
succeed in doing other activities from your account. Through SSH, you may present your friend
accesses to your accounts while also keeping your passwords hidden and unchanged or only the
function of running the mailing application.
3.5.5. Forwarding in ports
Among the beneficial SSH features, a key one is port forwarding. Setting up Port forward
provides the opportunity of changing insecure TCP connections to secure SSH connections. This
is also called SSH tunneling. We must know what port is being used. Ports are identifiers of
users in TCP communication. Thus a port is specified to the application with sudden spike of
demand among top of TCP communications. As an example, for applications using Simple Mail
Transfer Protocol or SMTP, the server listens by using the specific port ‘25’ hoping that
incoming SMTP requests use TCP before addressing data in the destination port 25. The TCP
thinks this is the SMTP server address. So it transfers the data to SMTP server applications.
3.5.6. Secure and remote execution of commands
The same commands need to be run by the system administrators on more than one PC. You
should be viewing active procedures for every user on four different PCs (group1, group2,
group3, group4) in the LAN with UNIX commands.

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/usr/ucb/w.
#!/bin/sh
For machine in group2
do
rsh $machine/usr/ucb/w
done
Consequences for using usr/ucb/w is the display of plain text throughout the network. If the
information by chance turns out as delicate, then it is not accepted. Rather we may choose ssh
instead of rsh. Here the commands as also their outcomes get encrypted while travelling through
its network. Solid authentication procedures are used to connect with remote machines. (Use the
command Ssh in place of rsh).
4. EXPERIMENT: ANALYSIS AND EVOLUTION
SSH refers to the protocol by which one is able to access the server of the cloud server and be
capable of running the shell commands. SSH keys can be used for recognizing the PCs to trust
without requiring passwords or interactions with the servers. Encryption in SSH happens through
the Secure Sockets Layer or SSL, which making it harder for such communications to get read or
intercepted.
Step 1: A remote server is needed.
(AWS E2) is used for the connection.

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An instance having key pairs is to be launched:

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The server IP address is to be copied.
To connect to the Ubuntu system, the below commands are used. All the commands are to be run
in the terminal starting with those for generation of keys.
ssh-keygen -t rsa

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Generation of keys:

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The keys get saved in form of the text enclosed within the block.
It can be seen that the access gets denied whenever one tries connecting through ssh-copy-id
root@ipaddress

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Hence, the command for seeking permission directly from the server is used.
The mode is then changed for accessing the .pam file in which the keys have been stored. Then a
direct connection from the amazon e2 server is sought.

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A detailed observation will tell that the concerned address is the server’s DNS and IP address.
Then, the connection between the server and this system will be established.
Next the files of the server will become accessible.

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5. Development of SSH
SSH makes use of secure shell and public-key cryptography which focus on to give encrypted
communication and verification in between two that is PC and user.
SSH innovation is completely based on a client server model which provides the best method to
remote access over gadgets. This is merely seen over unsecured network which is very much
similar to internet. Innovation is generally used by some of administrator that come up with
different capabilities like
 Logging in the PC and server that are remote for support and complete maintenance.
 This is merely needed for transferring files in between PC to PC.
 It focuses on remote execution of different commands
 This aims to offer certain support and updates.
Since the year 1960, Telnet is found to be used in the current login protocols. This is mainly
supplanted by SSH. It merely leads to protocols which come up better security features.
5.2. Advantages of SSH Key Authentication
IT teams can routine make use of SSH so that they can easily automate the secure access to
server. This is merely achieved by bypassing the requirement manually entering different sign in
credential for credentials. SSH protocol aims in encrypting different kind of traffic in between
two that is server and client at the time of transit. It merely highlights that if an individual is
eavesdropping on traffic that is through packet sniffing then it would not be accessed
appropriately. In addition, it does not even lead to decoding of the transmitted data.

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SSH is found to be resistant for most of the animal forces which attacks and aims in ensuring
prevention against certain attacks. This is merely used for gaining proper access to most of the
remote machines. Public key encryption aims in assuring that password does not need to be
provided over the network. This aims to assure some additional layer of security. SSH keys are
found to be the best way for securing and complaining with different regulation and mandates. It
ultimately provides the most suitable way that is needed for storage, evacuation and generating
data.
As there are huge number of SSH keys which are in use or even exist across the undertaking at
any given time. SSH key management software is found to be used for lowering both overhead
and manual managing keys.
5.3. Generation of SSH keys
SSH keys are generally presented in the form of pairs. The pairs consists of SSH key which is
both public and private. All these are generally paired by making use of solid algorithm which
makes it easy to fake a private key. This merely works irrespective of the fact whether individual
known the public key or not. SSH keys are mainly generated when the user provides other kind
of information. Both public and private keys are generated from the phrases of different words.
5.4. SSH Key Access
In general, a remote PC is recognized to a user when it is making use of public key. If anyhow a
user attempts to interface, then the remote PC imposes challenge from public key. For this, when
somebody having private key would be effective reacted and even unscrambled. If the challenges

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are effective answered, then the remote PC will give the access. The main task of SSH key is
generating keys, analyzing issues, sharing some public keys and lastly answering them. So, as a
result, procedure is completely transparent to most of the end-users.
6. CONCLUSION
The secure shell innovation provides the users with the tools of network security which helps in
praising the data security and the system. The encryption of the remote connections is possible
due to secure shell along with allowing of the administrators in selecting the authentication
medium which is required by them. The creation of secure remote backups is enabled by secure
shell along with the passage to traffic based on TCP. Several benefits of strong security is
provided by the protocol of SSH2 over the transport layer of TCP. This comprises of strategies
of secure authentication, integrity, data confidentiality and solid. The items of secure shell utilize
this particular layer of security for providing tools which have capabilities of transferring of files,
scripted command line access and are interactive in nature. The family of items of end-user
binary are broadly utilized both the administrators of the network along with the system.

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2. BIBLIOGRAPHY
Barrett, D.J., Barrett, D.J., Silverman, R.E. and Silverman, R., 2001. SSH, the Secure Shell: the
definitive guide. " O'Reilly Media, Inc.".
Garimella, D. and Kumar, R., 2015. Secure Shell-Its significance in Networking (SSH). Int. J. of
Application or Innovation in Engineering & Management, 4(3/12), pp.187-196.
https://www.ijaiem.org/Volume4Issue3/IJAIEM-2015-03-22-60.pdf
Https://acadpubl.eu/jsi/2017-116-13-22/articles/16/97.pdf
Http://tmu.ac.in/college-of-computing-sciences-and-it/wp
content/uploads/sites/17/2016/10/0416192.pdf
Ylonen, T. and Lonvick, C., 2006. The secure shell (SSH) protocol architecture.