Cryptography Coursework

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INM443 Cryptography

MSc in Cyber Security
MSci in Computer Science with Cyber Security

Resit Coursework

Ethical Hacking

Access the Cyber Security laboratory by following the instructions in the
coursework manual file and act as an ethical hacker for a company. Note that an
ethical hacker is an expert who attacks a security system on behalf of its owners,
seeking vulnerabilities that a malicious hacker could exploit.

You are challenged to identify flaws in a potential SQL database server by breaking
its crypto components and retrieve an encrypted credit card secret code of an e-
commerce company. The crypto algorithm used to encrypt the credit card secret
code is the RSA, but with weak security parameters. More information on the
scenario and the detail steps you need to follow consult the Coursework Manual
file found in MOODLE.

Output/Report Structure
It is expected to document in detail your methodology and work plan to achieve
your goals. Your submitted report should have the following structure and include
the following information:

1. Network discovery
In this section identify the system (e.g., IP addresses of the devices that exist in the
network, services running, OS software installed etc.) you will attack. Create a map
of the network in a diagram form with your findings.

[10 marks]

2. Breaking the system (2000-3000 words)
In this section discuss your attacking methodology. For example,
a) Perform a dictionary attack in the admin password to gain access to the SSH

server. Justify your answer. Clever solutions will earn full marks (e.g., in real-
life environment your dictionary password/username files are very large.)
[20 marks]

b) Cryptanalyze (by hand only) the encrypted email to gain useful information.

Provide details. Clever solutions will earn full marks (e.g., let’s assume you
don’t have access to online resources.). Justify your answers.

[20 marks]

c) Brute force the admin account in the SQL server to access your database
folder. Clever solutions will earn full marks (e.g., assume the database is

[20 marks]

d) Retrieve the credit card secret code from the accessed folder and calculate the

decryption RSA key (i.e., private key d). You will need the RSA encryption
key (i.e., public key e) and you can calculate it using Shamir’s secret sharing
scheme (more details are found in the Coursework Manual).

[20 marks]

e) Decrypt credit card’s secret code using the SageMath tool. Clever solutions
will earn full marks (e.g., discuss in the report how would you decrypt the
code if you didn’t had access to RSA tools).
[10 marks]

Justify your answers: In order to justify your finding in the coursework
report take screenshots from your steps.

3. Concluding Remarks
Conclude your work and describe what you have achieved.

Grading Criteria
Your mark will cover the coursework assessment component found in module
specifications for INM443. The exact weighting of the current security assessment
is 30% of the final mark.

Note that Marking follows the University Assessment and Feedback Policy:

Submission Dates
INM443 MSc students: The final report submission is due to the end of August
(4pm, 12th of August). It is essential to upload a single report in MOODLE under
INM443 MSc submission area.

Working environment
Instructions for your working environment are found in the coursework manual
file under INM443 Cryptography MOODLE area.

Cyber Security Laboratory Troubleshooting
If you don’t have access to the Cyber Security Laboratory or for troubleshooting
contact via email Warren Fernando ( and Nikos
Komninos (

Shared Coursework in Cyber Security
Instructions Manual
CybSecis an e-commerce company who sells products online. To support online

payments, CybSec has designed a network infrastructure illustrated in Figure 1.

This infrastructure includes an OuterFirewall, which controls incoming/outgoing

traffic, a DeMilitarized Zone (DMZ), where services are running, an

InnerFirewall, which controls incoming/outgoing traffic within the internal

network of the company.

Figure 1. Network Infrastructure of CybSec Company

In DMZ, several services run (SQL, Mail, Web etc.). Customers are accessing the

Web service to search for a product to buy. Upon decision, they enter personal

information (name, home address and card number) to buy products. Personal

information is stored in an SQL


Goal: Retrieve the credit card secret codes / owners’ names from the SQL


Assumptions: You are an investigator/ethical hacker and your operating system

(OS) is Kali Linux.

What to do: Follow the steps provided to achieve your goals. Appendixes contain

information for Linux and penetration testing commands that you can use to

achieve your goal.

How to access Investigators’s machine:

• Use VPN to access City’s net


( you need to sign into the page

using your city credentials.

• Once connected with the VPN, download and install VMware Horizon

View Client which is found here:


• Click on add server

• In a text box, enter ‘’ and click on connect

• Enter your City’/s credentials (for username make sure to use the format:

‘enterprise\yourusername, e.g. enterprise\absc853). If you don’t enter

enterprise\ before username authentication against your account won’t


• Double click win10-pool to load your Windows 10 environment.

• Double click the Investigator icon and connect to Kali Linux operating


• Login to Kali Linux OS

• You are now in the Investigator’s machine. This is your environment to

perform attacks.

Attacking the system by finding SSH admin’s credentials:

1) Use Linux Terminal (similar to CMD in Win) to enter penetration testing


2) Investigate which network your Linux host belongs to (“Ifconfig”).

3) Discover your network and services running (“nmap”).

4) To access the discovered services found in DMZ, you will need to “guess”

admin’s password. Check if you can perform dictionary attack on the SSH service

and grant access (“hydra”). Dictionary files are located at “/root/users.txt” for

username and “/root/pass.txt” for passwords.

5) Establish remote connection to the DMZ server using SSH and the

credentials found in step 4.

Attacking the system by finding admin’s credentials in the SQL service:

6) After remote login to the DMZ server explore the folders to find anything

useful to attack to the SQL database. The Mailbox folders contain an

encrypted email which is located at “/usr/home//Maildir”.

Cryptanalyse the cipher and read the email.

7) Once the additional information on the SQL server is found, you need to close

the ssh session using the command “exit”.

8) You can copy the files you need from the SQL Server to the investigator’s

machine via the SSH protocol using command “scp”.

9) In order to perform the brute force attack on some of the copied encrypted

files (if necessary) use command “john” to execute John the Ripper tool.

Accessing SQL service:

10) Once the SQL Server login/password information is retrieved, login to the

SQL Server using the command “mysql”.

11) Next, use the SQL commands to retrieve the financial information (credit

card secret, names) of the company.


12) The credit card secret code is encrypted with RSA-copied cipher. Use RSA

parameters found in previous step (i.e., step 6) to perform RSA cryptanalysis

(i.e., find d secret RSA parameter – for more information go through the

Lecture material).

13) During the RSA cryptanalysis phase, you will require a public key, e. The

calculation of e is done using Shamir’s secret sharing scheme (4, 4). In Table

1, you will find the points and their (x, y) coordinates. Work with members of

your group (or alone) to calculate the secret share s (according to Shamir’s

terminology). Note that s is your public key e, in the RSA context.

14) Once you have the RSA public key e, calculate the RSA secret component

d (use extended ECD).

15) Once you calculate RSA secret d, go to your Kali Linux environment in

the path “/bin/SageMath” and run “./sage”. Using SageMath decrypt the

credit card secret code.

16) In order to justify your finding in the coursework report record the previous

steps with screenshots.

Table 1 – Shamir’s Secret Table.

APPENDIX A – Working with Linux file system
To work with files and directories, you will need to know a few basic commands:
• cd – That ~ to the left of the prompt represents your home directory, which is the

terminal’s default directory. To change to another directory, you can use the cd command.
For example cd / would change to the root directory, cd Downloads would change to the
Downloads directory inside the current directory (so this only opens your Downloads
directory if the terminal is in your home directory), cd /home/you/Downloads would
change to your Downloads directory from anywhere in the system, cd ~ would change to
your home directory, and cd .. would go up a directory.

• ls – The ls command lists the files in the current directory.
• mkdir – The mkdir command makes a new directory. mkdir example would create a

new directory named example in the current directory, while mkdir
/home/you/Downloads/test would create a new directory named test in your Downloads

• rm – The rm command removes a file. For example, rm example removes the file named
example in the current directory and rm /home/you/Downloads/example removes the
file named example in the Downloads directory.

• cp – The cp command copies a file from one location to another. For example, cp
example /home/User/Downloads copies the file named example in the current directory
to /home/User/Downloads.

• mv – The mv command moves a file from one location to another. It works exactly like
the cp command above, but moves the file instead of creating a copy. mv can also be used
to rename files. For example, mv original renamed moves a file named original in the
current directory to a file named renamed in the current directory, effectively renaming

Move around your file system with cd, view files in the current directory with ls, create
directories with mkdir, and manage files with the rm, cp, and mv commands.

User Prime p from
(mod p)

Public Value

Share y-

User1 4637 1069 3462
User2 4637 324 2262
User3 4637 97 4166
User5 4637 2917 3410
User6 8923 3020 6506
User7 8923 4828 6715
User11 8923 5437 8283
User16 8923 5623 6896
User4 7919 2744 2751
User8 7919 3332 1667
User13 7919 7806 7844
User14 7919 3560 7370

APPENDIX B – Tab Completion
Tab completion is a very useful trick. While typing something – a command, file name, or
some other types of arguments – you can press Tab to autocomplete what you’re typing. For
example, if you type firef at the terminal and press Tab, firefox automatically appears. This
saves you from having to type things exactly – you can press Tab and the shell will finish
typing for you. This also works with folders, file names, and package names. In many cases,
the shell won’t know what you’re trying to type because there are multiple matches. Press the
Tab key a second time and you’ll see a list of possible matches. Continue typing a few more
letters to narrow things down and press Tab again to continue. For more information about
command usage type “man ”. For example “man ls” will show you
manual for command “ls”.

APPENDIX C – ifconfig command
ifconfig – configure a network interface
ifconfig [interface]
ifconfig interface [aftype] options | address …
Ifconfig is used to configure the kernel-resident network interfaces. It is used at boot time to
set up interfaces as necessary. After that, it is usually only needed when debugging or when
system tuning is needed.
If no arguments are given, ifconfig displays the status of the currently active interfaces. If a
single interface argument is given, it displays the status of the given interface only; if a single –
a argument is given, it displays the status of all interfaces, even those that are down. Otherwise,
it configures an interface.
Address Families
If the first argument after the interface name is recognized as the name of a supported address
family, that address family is used for decoding and displaying all protocol addresses. Currently
supported address families include inet (TCP/IP, default), inet6(IPv6), ax25 (AMPR Packet
Radio), ddp (Appletalk Phase 2), ipx (Novell IPX) andnetrom (AMPR Packet radio). All
numbers supplied as parts in IPv4 dotted decimal notation may be decimal, octal, or
hexadecimal, as specified in the ISO C standard (that is, a leading 0x or 0X implies
hexadecimal; otherwise, a leading ‘0’ implies octal; otherwise, the number is interpreted as
decimal). Use of hexamedial and octal numbers is not RFC-compliant and therefore its use is
discouraged and may go away.

The name of the interface. This is usually a driver name followed by a unit number, for
example eth0 for the first Ethernet interface.

This flag causes the interface to be activated. It is implicitly specified if an address is
assigned to the interface.

This flag causes the driver for this interface to be shut down.

Enable or disable the use of the ARP protocol on this interface.

Enable or disable the promiscuous mode of the interface. If selected, all packets on the
network will be received by the interface.

Enable or disable all-multicast mode. If selected, all multicast packets on the network
will be received by the interface.

metric N
This parameter sets the interface metric. It is not available under GNU/Linux.

mtu N
This parameter sets the Maximum Transfer Unit (MTU) of an interface.

dstaddr addr
Set the remote IP address for a point-to-point link (such as PPP). This keyword is now
obsolete; use the pointopoint keyword instead.

netmask addr

Set the IP network mask for this interface. This value defaults to the usual class A, B
or C network mask (as derived from the interface IP address), but it can be set to any

add addr/prefixlen
Add an IPv6 address to an interface.

del addr/prefixlen
Remove an IPv6 address from an interface.

Create a new SIT (IPv6-in-IPv4) device, tunnelling to the given destination.

irq addr
Set the interrupt line used by this device. Not all devices can dynamically change their
IRQ setting.

io_addr addr
Set the start address in I/O space for this device.

mem_start addr
Set the start address for shared memory used by this device. Only a few devices need

media type
Set the physical port or medium type to be used by the device. Not all devices can
change this setting, and those that can vary in what values they support. Typical values
for type are 10base2 (thin Ethernet), 10baseT (twisted-pair 10Mbps
Ethernet), AUI (external transceiver) and so on. The special medium type of auto can
be used to tell the driver to auto-sense the media. Again, not all drivers can do this.

[-]broadcast [addr]
If the address argument is given, set the protocol broadcast address for this interface.
Otherwise, set (or clear) the IFF_BROADCAST flag for the interface.

[-]pointopoint [addr]
This keyword enables the point-to-point mode of an interface, meaning that it is a
direct link between two machines with nobody else listening on it.
If the address argument is also given, set the protocol address of the other side of the
link, just like the obsolete dstaddr keyword does. Otherwise, set or clear
theIFF_POINTOPOINT flag for the interface.

hw class address
Set the hardware address of this interface, if the device driver supports this operation.
The keyword must be followed by the name of the hardware class and the printable
ASCII equivalent of the hardware address. Hardware classes currently supported
include ether (Ethernet), ax25 (AMPR AX.25), ARCnet and netrom (AMPR

Set the multicast flag on the interface. This should not normally be needed as the drivers
set the flag correctly themselves.

The IP address to be assigned to this interface.

txqueuelen length
Set the length of the transmit queue of the device. It is useful to set this to small values
for slower devices with a high latency (modem links, ISDN) to prevent fast bulk
transfers from disturbing interactive traffic like telnet too much.

For more information type in the shell “man ifconfig”

APPENDIX D – nmap command
nmap – Network exploration tool and security / port scanner
nmap [Scan Type…] [Options] {target specification}
Nmap (“Network Mapper”) is an open source tool for network exploration and security
auditing. It was designed to rapidly scan large networks, although it works fine against single
hosts. Nmap uses raw IP packets in novel ways to determine what hosts are available on the
network, what services (application name and version) those hosts are offering, what operating
systems (and OS versions) they are running, what type of packet filters/firewalls are in use, and
dozens of other characteristics. While Nmap is commonly used for security audits, many
systems and network administrators find it useful for routine tasks such as network inventory,
managing service upgrade schedules, and monitoring host or service uptime.
The output from Nmap is a list of scanned targets, with supplemental information on each
depending on the options used. Key among that information is the “interesting ports table”..
That table lists the port number and protocol, service name, and state. The state is either open,
filtered, closed, or unfiltered. Open. means that an application on the target machine is listening
for connections/packets on that port. Filtered. means that a firewall, filter, or other network
obstacle is blocking the port so that Nmap cannot tell whether it is open or closed. Closed. ports
have no application listening on them, though they could open up at any time. Ports are
classified as unfiltered. when they are responsive to Nmap’s probes, but Nmap cannot
determine whether they are open or closed. Nmap reports the state combinations open|filtered.
and closed|filtered. when it cannot determine which of the two states describe a port. The port
table may also include software version details when version detection has been requested.
When an IP protocol scan is requested (-sO), Nmap provides information on supported IP
protocols rather than listening ports.
In addition to the interesting ports table, Nmap can provide further information on targets,
including reverse DNS names, operating system guesses, device types, and MAC addresses.
A typical Nmap scan is shown in Example 1. The only Nmap arguments used in this example
are -A, to enable OS and version detection, script scanning, and traceroute; -T4 for faster
execution; and then the two target hostnames.
Example 1. A representative Nmap scan

# nmap -A -T4

Nmap scan report for (
Host is up (0.045s latency).
Not shown: 993 filtered ports
22/tcp open ssh OpenSSH 4.3 (protocol 2.0)
| ssh-hostkey: 1024 60:ac:4d:51:b1:cd:85:09:12:16:92:76:1d:5d:27:6e (DSA)
|_2048 2c:22:75:60:4b:c3:3b:18:a2:97:2c:96:7e:28:dc:dd (RSA)
25/tcp closed smtp
53/tcp open domain
70/tcp closed gopher
80/tcp open http Apache httpd 2.2.3 ((CentOS))
|_html-title: Go ahead and ScanMe!
| http-methods: Potentially risky methods: TRACE
113/tcp closed auth

31337/tcp closed Elite
Device type: general purpose
Running: Linux 2.6.X
OS details: Linux 2.6.13 – 2.6.31, Linux 2.6.18
Network Distance: 13 hops

TRACEROUTE (using port 80/tcp)
[Cut first 10 hops for brevity]
11 80.33 ms (
12 137.52 ms (
13 44.15 ms (

Nmap done: 1 IP address (1 host up) scanned in 22.19 seconds

The newest version of Nmap can be obtained from The newest version of
this man page is available at It is also included as a chapter
of Nmap Network Scanning: The Official Nmap Project Guide to Network Discovery and
Security Scanning (see
Options Summary
This options summary is printed when Nmap is run with no arguments, and the latest version
is always available at It helps people remember the
most common options, but is no substitute for the in-depth documentation in the rest of this
manual. Some obscure options aren’t even included here.

Nmap 5.51 ( )
Usage: nmap [Scan Type(s)] [Options] {target specification}
Can pass hostnames, IP addresses, networks, etc.
Ex:,; 10.0.0-255.1-254
-iL : Input from list of hosts/networks
-iR : Choose random targets
–exclude : Exclude hosts/networks
–excludefile : Exclude list from file
-sL: List Scan – simply list targets to scan
-sn: Ping Scan – disable port scan
-Pn: Treat all hosts as online — skip host discovery
-PS/PA/PU/PY[portlist]: TCP SYN/ACK, UDP or SCTP discovery to given ports
-PE/PP/PM: ICMP echo, timestamp, and netmask request discovery probes
-PO[protocol list]: IP Protocol Ping
-n/-R: Never do DNS resolution/Always resolve [default: sometimes]
–dns-servers : Specify custom DNS servers
–system-dns: Use OS’s DNS resolver
–traceroute: Trace hop path to each host
-sS/sT/sA/sW/sM: TCP SYN/Connect()/ACK/Window/Maimon scans
-sU: UDP Scan
-sN/sF/sX: TCP Null, FIN, and Xmas scans
–scanflags : Customize TCP scan flags
-sI : Idle scan

-sO: IP protocol scan
-b : FTP bounce scan
-p : Only scan specified ports
Ex: -p22; -p1-65535; -p U:53,111,137,T:21-25,80,139,8080,S:9
-F: Fast mode – Scan fewer ports than the default scan
-r: Scan ports consecutively – don’t randomize
–top-ports : Scan most common ports
–port-ratio : Scan ports more common than
-sV: Probe open ports to determine service/version info
–version-intensity : Set from 0 (light) to 9 (try all probes)
–version-light: Limit to most likely probes (intensity 2)
–version-all: Try every single probe (intensity 9)
–version-trace: Show detailed version scan activity (for debugging)
-sC: equivalent to –script=default
–script=: is a comma separated list of
directories, script-files or script-categories
–script-args=: provide arguments to scripts
–script-trace: Show all data sent and received
–script-updatedb: Update the script database.
-O: Enable OS detection
–osscan-limit: Limit OS detection to promising targets
–osscan-guess: Guess OS more aggressively
Options which take

-oN/-oX/-oS/-oG : Output scan in normal, XML, s|: Output in the three major formats at once
-v: Increase verbosity level (use -vv or more for greater effect)
-d: Increase debugging level (use -dd or more for greater effect)
–reason: Display the reason a port is in a particular state
–open: Only show open (or possibly open) ports
–packet-trace: Show all packets sent and received
–iflist: Print host interfaces and routes (for debugging)
–log-errors: Log errors/warnings to the normal-format output file
–append-output: Append to rather than clobber specified output files
–resume : Resume an aborted scan
–stylesheet : XSL stylesheet to transform XML output to HTML
–webxml: Reference stylesheet from Nmap.Org for more portable XML
–no-stylesheet: Prevent associating of XSL stylesheet w/XML output
-6: Enable IPv6 scanning
-A: Enable OS detection, version detection, script scanning, and traceroute
–datadir : Specify custom Nmap data file location
–send-eth/–send-ip: Send using raw ethernet frames or IP packets
–privileged: Assume that the user is fully privileged
–unprivileged: Assume the user lacks raw socket privileges
-V: Print version number
-h: Print this help summary page.
nmap -v -A
nmap -v -sn
nmap -v -iR 10000 -Pn -p 80

For more information use the link:

APPENDIX E – SSH protocol

Secure Shell (SSH) is cryptographic network protocol for secure data communication,
remote command-line login, remote command execution, and other secure network
services between two networked computers. It connects, via a secure channel over an insecure
network, a server and a client running SSH server and SSH client programs,
respectively.[1] The protocol specification distinguishes between two major versions that are
referred to as SSH-1 and SSH-2.
The best-known application of the protocol is for access to shell accounts on Unix-
like operating systems, but it can also be used in a similar fashion for accounts on Windows. It
was designed as a replacement for Telnet and other insecure remote shell protocols such as the
Berkeley rsh and rexec protocols, which send information, notably passwords, in plaintext,
rendering them susceptible to interception and disclosure using packet
analysis. The encryption used by SSH is intended to provide confidentiality and integrity of
data over an unsecured network, such as the Internet.
SSH uses public-key cryptography to authenticate the remote computer and allow it to
authenticate the user, if necessary. There are several ways to use SSH; one is to use
automatically generated public-private key pairs to simply encrypt a network connection, and
then use password authentication to log on.
Another is to use a manually generated public-private key pair to perform the authentication,
allowing users or programs to log in without having to specify a password. In this scenario,
anyone can produce a matching pair of different keys (public and private). The public key is
placed on all computers that must allow access to the owner of the matching private key (the
owner keeps the private key secret). While authentication is based on the private key, the key
itself is never transferred through the network during authentication. SSH only verifies whether
the same person offering the public key also owns the matching private key. In all versions of
SSH it is important to verify unknown public keys, i.e., associate the public keys with
identities, before accepting them as valid. Accepting an attacker’s public key without validation
will authorize an unauthorized attacker as a valid user.


hydra – A very fast network logon cracker which support many different services
hydra [[[-l LOGIN|-L FILE] [-p PASS|-P FILE]] | [-C FILE]] [-e ns] [-4/6]
[-o FILE] [-t TASKS] [-M FILE [-T TASKS]] [-w TIME] [-f] [-s PORT] [-S] [-vV]
server service [OPT]

Hydra is a parallized login cracker which supports numerous protocols to attack. New modules
are easy to add, beside that, it is flexible and very fast.
This tool gives researchers and security consultants the possiblity to show how easy it would
be to gain unauthorized access from remote to a system.
Currently this tool supports:
AFP, Cisco AAA, Cisco auth, Cisco enable, CVS, Firebird, FTP, HTTP-FORM-GET,
Subversion, Teamspeak (TS2), TELNET, VMware-Auth, VNC and XMPP.

restore a previous aborted/crashed session

connect via SSL

if the service is on a different default port, define it here

or -L FILE login with LOGIN name, or load several logins from FILE

or -P FILE try password PASS, or load several passwords from FILE
-e ns

additional checks, “n” for null password, “s” try login as pass

colon separated “login:pass” format, instead of -L/-P options

server list for parallel attacks, one entry per line

write found login/password pairs to FILE instead of stdout

exit after the first found login/password pair (per host if -M)

run TASKS number of connects in parallel (default: 16)

defines the max wait time in seconds for responses (default: 30)
-4 / -6

prefer IPv4 (default) or IPv6 addresses
-v / -V

verbose mode / show login+pass combination for each attempt

the target server (use either this OR the -M option)

the service to crack. Supported protocols: afp cisco cisco-enable cvs firebird ftp[s]
http[s]-{head|get} http[s]-{get|post}-form http-proxy icq irc imap ldap2 ldap3[-
{cram|digest}md5] mssql mysql ncp nntp oracle oracle-listener oracle-sid pcnfs pop3
pcanywhere postgres rexec rlogin rsh sapr3 sip smb smtp smtp-enum snmp socks5 ssh
svn teamspeak telnet vnc vmauthd xmpp

some service modules need special input (see README!)

-h, –help
Show summary of options.

For more information type “man hydra” in the shell



ssh – OpenSSH SSH client (remote login program)


ssh [-1246AaCfgkMNnqsTtVvXxY] [-b bind_address] [-c cipher_spec] [-D
[bind_address:]port] [-e escape_char] [-F configfile]
[-i identity_file] [-L [bind_address:]port:host:hostport]
[-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port] [-R
[bind_address:]port:host:hostport] [-S ctl_path] [-w tunnel:tunnel]
[user@]hostname [command]


ssh (SSH client) is a program for logging into a remote machine and for
executing commands on a remote machine. It is intended to replace rlogin
and rsh, and provide secure encrypted communications between two
untrusted hosts over an insecure network. X11 connections and arbitrary
TCP ports can also be forwarded over the secure channel.

ssh connects and logs into the specified hostname (with optional user
name). The user must prove his/her identity to the remote machine using
one of several methods depending on the protocol version used (see

If command is specified, it is executed on the remote host instead of a
login shell.

The options are as follows:

-1 Forces ssh to try protocol version 1 only.

-2 Forces ssh to try protocol version 2 only.

-4 Forces ssh to use IPv4 addresses only.

-6 Forces ssh to use IPv6 addresses only.

-A Enables forwarding of the authentication agent connection. This
can also be specified on a per-host basis in a configuration

Agent forwarding should be enabled with caution. Users with the
ability to bypass file permissions on the remote host (for the
agent’s Unix-domain socket) can access the local agent through
the forwarded connection. An attacker cannot obtain key material
from the agent, however they can perform operations on the keys

that enable them to authenticate using the identities loaded into
the agent.

-a Disables forwarding of the authentication agent connection.

-b bind_address
Use bind_address on the local machine as the source address of
the connection. Only useful on systems with more than one

-C Requests compression of all data (including stdin, stdout,
stderr, and data for forwarded X11 and TCP connections). The
compression algorithm is the same used by gzip(1), and the
“level” can be controlled by the CompressionLevel option for pro-
tocol version 1. Compression is desirable on modem lines and
other slow connections, but will only slow down things on fast
networks. The default value can be set on a host-by-host basis
in the configuration files; see the Compression option.

-c cipher_spec
Selects the cipher specification for encrypting the session.

Protocol version 1 allows specification of a single cipher. The
supported values are “3des”, “blowfish”, and “des”. 3des
(triple-des) is an encrypt-decrypt-encrypt triple with three dif-
ferent keys. It is believed to be secure. blowfish is a fast
block cipher; it appears very secure and is much faster than
3des. des is only supported in the ssh client for interoperabil-
ity with legacy protocol 1 implementations that do not support
the 3des cipher. Its use is strongly discouraged due to crypto-
graphic weaknesses. The default is “3des”.

For protocol version 2, cipher_spec is a comma-separated list of
ciphers listed in order of preference. The supported ciphers
are: 3des-cbc, aes128-cbc, aes192-cbc, aes256-cbc, aes128-ctr,
aes192-ctr, aes256-ctr, arcfour128, arcfour256, arcfour, blow-
fish-cbc, and cast128-cbc. The default is:


-D [bind_address:]port
Specifies a local “dynamic” application-level port forwarding.
This works by allocating a socket to listen to port on the local
side, optionally bound to the specified bind_address. Whenever a
connection is made to this port, the connection is forwarded over
the secure channel, and the application protocol is then used to
determine where to connect to from the remote machine. Currently
the SOCKS4 and SOCKS5 protocols are supported, and ssh will act

as a SOCKS server. Only root can forward privileged ports.
Dynamic port forwardings can also be specified in the configura-
tion file.

IPv6 addresses can be specified with an alternative syntax:
[bind_address/]port or by enclosing the address in square brack-
ets. Only the superuser can forward privileged ports. By
default, the local port is bound in accordance with the
GatewayPorts setting. However, an explicit bind_address may be
used to bind the connection to a specific address. The
bind_address of “localhost” indicates that the listening port be
bound for local use only, while an empty address or ‘*’ indicates
that the port should be available from all interfaces.

-e escape_char
Sets the escape character for sessions with a pty (default: ‘~’).
The escape character is only recognized at the beginning of a
line. The escape character followed by a dot (‘.’) closes the
connection; followed by control-Z suspends the connection; and
followed by itself sends the escape character once. Setting the
character to “none” disables any escapes and makes the session
fully transparent.

-F configfile
Specifies an alternative per-user configuration file. If a con-
figuration file is given on the command line, the system-wide
configuration file (/etc/ssh/ssh_config) will be ignored. The
default for the per-user configuration file is ~/.ssh/config.

-f Requests ssh to go to background just before command execution.
This is useful if ssh is going to ask for passwords or
passphrases, but the user wants it in the background. This
implies -n. The recommended way to start X11 programs at a
remote site is with something like ssh -f host xterm.

-g Allows remote hosts to connect to local forwarded ports.

-I smartcard_device
Specify the device ssh should use to communicate with a smartcard
used for storing the user’s private RSA key. This option is only
available if support for smartcard devices is compiled in
(default is no support).

-i identity_file
Selects a file from which the identity (private key) for RSA or
DSA authentication is read. The default is ~/.ssh/identity for
protocol version 1, and ~/.ssh/id_rsa and ~/.ssh/id_dsa for pro-
tocol version 2. Identity files may also be specified on a per-
host basis in the configuration file. It is possible to have
multiple -i options (and multiple identities specified in config-

uration files).

-k Disables forwarding (delegation) of GSSAPI credentials to the

-L [bind_address:]port:host:hostport
Specifies that the given port on the local (client) host is to be
forwarded to the given host and port on the remote side. This
works by allocating a socket to listen to port on the local side,
optionally bound to the specified bind_address. Whenever a con-
nection is made to this port, the connection is forwarded over
the secure channel, and a connection is made to host port
hostport from the remote machine. Port forwardings can also be
specified in the configuration file. IPv6 addresses can be spec-
ified with an alternative syntax:
[bind_address/]port/host/hostport or by enclosing the address in
square brackets. Only the superuser can forward privileged
ports. By default, the local port is bound in accordance with
the GatewayPorts setting. However, an explicit bind_address may
be used to bind the connection to a specific address. The
bind_address of “localhost” indicates that the listening port be
bound for local use only, while an empty address or ‘*’ indicates
that the port should be available from all interfaces.

-l login_name
Specifies the user to log in as on the remote machine. This also
may be specified on a per-host basis in the configuration file.

-M Places the ssh client into “master” mode for connection sharing.
Multiple -M options places ssh into “master” mode with confirma-
tion required before slave connections are accepted. Refer to
the description of ControlMaster in ssh_config(5) for details.

-m mac_spec
Additionally, for protocol version 2 a comma-separated list of
MAC (message authentication code) algorithms can be specified in
order of preference. See the MACs keyword for more information.

-N Do not execute a remote command. This is useful for just for-
warding ports (protocol version 2 only).

-n Redirects stdin from /dev/null (actually, prevents reading from
stdin). This must be used when ssh is run in the background. A
common trick is to use this to run X11 programs on a remote
machine. For example, ssh -n emacs & will
start an emacs on, and the X11 connection will
be automatically forwarded over an encrypted channel. The ssh
program will be put in the background. (This does not work if
ssh needs to ask for a password or passphrase; see also the -f

-O ctl_cmd
Control an active connection multiplexing master process. When
the -O option is specified, the ctl_cmd argument is interpreted
and passed to the master process. Valid commands are: “check”
(check that the master process is running) and “exit” (request
the master to exit).

-o option
Can be used to give options in the format used in the configura-
tion file. This is useful for specifying options for which there
is no separate command-line flag. For full details of the
options listed below, and their possible values, see



-p port
Port to connect to on the remote host. This can be specified on
a per-host basis in the configuration file.

-q Quiet mode. Causes all warning and diagnostic messages to be

-R [bind_address:]port:host:hostport
Specifies that the given port on the remote (server) host is to
be forwarded to the given host and port on the local side. This
works by allocating a socket to listen to port on the remote
side, and whenever a connection is made to this port, the connec-
tion is forwarded over the secure channel, and a connection is
made to host port hostport from the local machine.

Port forwardings can also be specified in the configuration file.
Privileged ports can be forwarded only when logging in as root on
the remote machine. IPv6 addresses can be specified by enclosing
the address in square braces or using an alternative syntax:

By default, the listening socket on the server will be bound to

the loopback interface only. This may be overriden by specifying
a bind_address. An empty bind_address, or the address ‘*’, indi-
cates that the remote socket should listen on all interfaces.
Specifying a remote bind_address will only succeed if the
server’s GatewayPorts option is enabled (see sshd_config(5)).

-S ctl_path
Specifies the location of a control socket for connection shar-
ing. Refer to the description of ControlPath and ControlMaster
in ssh_config(5) for details.

-s May be used to request invocation of a subsystem on the remote
system. Subsystems are a feature of the SSH2 protocol which
facilitate the use of SSH as a secure transport for other appli-
cations (eg. sftp(1)). The subsystem is specified as the remote

-T Disable pseudo-tty allocation.

-t Force pseudo-tty allocation. This can be used to execute arbi-
trary screen-based programs on a remote machine, which can be
very useful, e.g., when implementing menu services. Multiple -t
options force tty allocation, even if ssh has no local tty.

-V Display the version number and exit.

-v Verbose mode. Causes ssh to print debugging messages about its
progress. This is helpful in debugging connection, authentica-
tion, and configuration problems. Multiple -v options increase
the verbosity. The maximum is 3.

-w tunnel:tunnel
Requests a tun(4) device on the client (first tunnel arg) and
server (second tunnel arg). The devices may be specified by
numerical ID or the keyword “any”, which uses the next available
tunnel device. See also the Tunnel directive in ssh_config(5).

-X Enables X11 forwarding. This can also be specified on a per-host
basis in a configuration file.

X11 forwarding should be enabled with caution. Users with the
ability to bypass file permissions on the remote host (for the
user’s X authorization database) can access the local X11 display
through the forwarded connection. An attacker may then be able
to perform activities such as keystroke monitoring.

For this reason, X11 forwarding is subjected to X11 SECURITY
extension restrictions by default. Please refer to the ssh -Y
option and the ForwardX11Trusted directive in ssh_config(5) for
more information.

-x Disables X11 forwarding.

-Y Enables trusted X11 forwarding. Trusted X11 forwardings are not
subjected to the X11 SECURITY extension controls.

ssh may additionally obtain configuration data from a per-user configura-
tion file and a system-wide configuration file. The file format and con-
figuration options are described in ssh_config(5).

ssh exits with the exit status of the remote command or with 255 if an
error occurred.

For more information use command “man ssh”.

APPENDIX H – scp command

scp allows files to be copied to, from, or between different hosts. It uses ssh for data transfer
and provides the same authentication and same level of security as ssh.
Copy the file “foobar.txt” from a remote host to the local host

$ scp /some/local/directory

Copy the file “foobar.txt” from the local host to a remote host

$ scp foobar.txt

Copy the directory “foo” from the local host to a remote host’s directory “bar”

$ scp -r foo

Copy the file “foobar.txt” from remote host “” to remote host “”

$ scp \

Copying the files “foo.txt” and “bar.txt” from the local host to your home directory on the
remote host

$ scp foo.txt bar.txt

Copy the file “foobar.txt” from the local host to a remote host using port 2264

$ scp -P 2264 foobar.txt

Copy multiple files from the remote host to your current directory on the local host

$ scp\{a,b,c\} .

$ scp\{foo.txt,bar.txt\} .

For more information type “man scp”

APPENDIX I – John the Ripper Tool / Command
To run John, you need to supply it with some password files and optionally specify a cracking
mode, like this, using the default order of modes and assuming that “passwd” is a copy of your
password file:

john passwd

or, to restrict it to the wordlist mode only, but permitting the use of word mangling rules:

john –wordlist=password.lst –rules passwd

Cracked passwords will be printed to the terminal and saved in the file called $JOHN/john.pot
(in the documentation and in the configuration file for John, “$JOHN” refers to John’s “home
directory”; which directory it really is depends on how you installed John). The
$JOHN/john.pot file is also used to not load password hashes that you already cracked when
you run John the next time.

To retrieve the cracked passwords, run:

john –show passwd
While cracking, you can press any key for status, or ‘q’ or Ctrl-C to abort the session saving its
state to a file ($JOHN/john.rec by default). If you press Ctrl-C for a second time before John
had a chance to complete handling of your first Ctrl-C, John will abort immediately without
saving. By default, the state is also saved every 10 minutes to permit for recovery in case of a

To continue an interrupted session, run:
john –restore
These are just the most essential things you can do with John. For a complete list of command
line options and for more complicated usage examples you should refer to OPTIONS and
EXAMPLES, respectively.

Please note that “binary” (pre-compiled) distributions of John may include alternate
executables instead of just “john”. You may need to choose the executable that fits your system
best, e.g. “john-omp” to take advantage of multiple CPUs and/or CPU cores.

For more information type “man john”.

APPENDIX K – mysql command

mysql – the MySQL command-line tool


mysql [options] db_name


mysql is a simple SQL shell with input line editing capabilities. It supports interactive and
noninteractive use. When used interactively, query results are presented in an ASCII-table
format. When used noninteractively (for example, as a filter), the result is presented in tab-
separated format. The output format can be changed using command options.

If you have problems due to insufficient memory for large result sets, use the –quick option.
This forces mysql to retrieve results from the server a row at a time rather than retrieving the
entire result set and buffering it in memory before displaying it. This is done by returning the
result set using the mysql_use_result() C API function in the client/server library rather than

Using mysql is very easy. Invoke it from the prompt of your command interpreter as follows:

shell> mysql db_name
shell> mysql –user=user_name –password=your_password db_name
Then type an SQL statement, end it with “;”, \g, or \G and press Enter.
As of MySQL 5.1.10, typing Control+C causes mysql to attempt to kill the current statement.
If this cannot be done, or Control+C is typed again before the statement is killed, mysql exits.
Previously, Control+C caused mysql to exit in all cases.

You can execute SQL statements in a script file (batch file) like this:

shell> mysql db_name < script.sql >
On Unix, the mysql client writes a record of executed statements to a history file. See the
section called “MYSQL HISTORY FILE”.
Mysql Options

mysql supports the following options, which can be specified on the command line or in the
[mysql] and [client] groups of an option file. mysql also supports the options for processing
option files described at Section, “Command-Line Options that Affect Option-File

• –help, -?
Display a help message and exit.

• –auto-rehash

Enable automatic rehashing. This option is on by default, which enables database, table, and
column name completion. Use –disable-auto-rehash to disable rehashing. That causes mysql
to start faster, but you must issue the rehash command if you want to use name completion.

To complete a name, enter the first part and press Tab. If the name is unambiguous, mysql
completes it. Otherwise, you can press Tab again to see the possible names that begin with
what you have typed so far. Completion does not occur if there is no default database.

• –batch, -B
Print results using tab as the column separator, with each row on a new line. With this option,
mysql does not use the history file.

Batch mode results in nontabular output format and escaping of special characters. Escaping
may be disabled by using raw mode; see the description for the –raw option.

• –bind-address=ip_address
On a computer having multiple network interfaces, this option can be used to select which
interface is employed when connecting to the MySQL server.

This option is supported only in the version of the mysql client that is supplied with MySQL
Cluster, beginning with MySQL Cluster NDB 6.3.4. It is not available in standard MySQL 5.1

• –character-sets-dir=path
The directory where character sets are installed. See Section 10.5, “Character Set

• –column-names
Write column names in results.

• –column-type-info, -m
Display result set metadata. This option was added in MySQL 5.1.14. (Before that, use –debug-
info.) The -m short option was added in MySQL 5.1.21.

• –comments, -c
Whether to preserve comments in statements sent to the server. The default is –skip-comments
(discard comments), enable with –comments (preserve comments). This option was added in
MySQL 5.1.23.

• –compress, -C
Compress all information sent between the client and the server if both support compression.

• –database=db_name, -D db_name
The database to use. This is useful primarily in an option file.

• –debug[=debug_options], -# [debug_options]
Write a debugging log. A typical debug_options string is ‘d:t:o,file_name’. The default is

• –debug-check

Print some debugging information when the program exits. This option was added in MySQL

• –debug-info, -T
Before MySQL 5.1.14, this option prints debugging information and memory and CPU usage
statistics when the program exits, and also causes display of result set metadata during
execution. As of MySQL 5.1.14, use –column-type-info to display result set metadata.

• –default-character-set=charset_name
Use charset_name as the default character set for the client and connection.

A common issue that can occur when the operating system uses utf8 or another multi-byte
character set is that output from the mysql client is formatted incorrectly, due to the fact that
the MySQL client uses the latin1 character set by default. You can usually fix such issues by
using this option to force the client to use the system character set instead.

See Section 10.5, “Character Set Configuration”, for more information.

• –delimiter=str
Set the statement delimiter. The default is the semicolon character (“;”).

• –disable-named-commands
Disable named commands. Use the \* form only, or use named commands only at the beginning
of a line ending with a semicolon (“;”). mysql starts with this option enabled by default.
However, even with this option, long-format commands still work from the first line. See the
section called “MYSQL COMMANDS”.

• –execute=statement, -e statement
Execute the statement and quit. The default output format is like that produced with –batch.
See Section, “Using Options on the Command Line”, for some examples. With this
option, mysql does not use the history file.

• –force, -f
Continue even if an SQL error occurs.

• –host=host_name, -h host_name
Connect to the MySQL server on the given host.

• –html, -H
Produce HTML output.

• –ignore-spaces, -i
Ignore spaces after function names. The effect of this is described in the discussion for the
IGNORE_SPACE SQL mode (see Section 5.1.7, “Server SQL Modes”).

• –line-numbers
Write line numbers for errors. Disable this with –skip-line-numbers.

• –local-infile[={0|1}]

Enable or disable LOCAL capability for LOAD DATA INFILE. With no value, the option
enables LOCAL. The option may be given as –local-infile=0 or –local-infile=1 to explicitly
disable or enable LOCAL. Enabling LOCAL has no effect if the server does not also support

• –named-commands, -G
Enable named mysql commands. Long-format commands are permitted, not just short-format
commands. For example, quit and \q both are recognized. Use –skip-named-commands to
disable named commands. See the section called “MYSQL COMMANDS”.

• –no-auto-rehash, -A
This has the same effect as -skip-auto-rehash. See the description for –auto-rehash.

• –no-beep, -b
Do not beep when errors occur.

• –no-named-commands, -g
Deprecated, use –disable-named-commands instead. –no-named-commands is removed in
MySQL 5.5.

• –no-pager
Deprecated form of –skip-pager. See the –pager option. –no-pager is removed in MySQL 5.5.

• –no-tee
Deprecated form of –skip-tee. See the –tee option. –no-tee is removed in MySQL 5.5.

• –one-database, -o
Ignore statements except those that occur while the default database is the one named on the
command line. This option is rudimentary and should be used with care. Statement filtering is
based only on USE statements.

Initially, mysql executes statements in the input because specifying a database db_name on the
command line is equivalent to inserting USE db_name at the beginning of the input. Then, for
each USE statement encountered, mysql accepts or rejects following statements depending on
whether the database named is the one on the command line. The content of the statements is

Suppose that mysql is invoked to process this set of statements:

USE db2;
DROP TABLE db1.t1;
CREATE TABLE db1.t1 (i INT);
USE db1;
CREATE TABLE db2.t1 (j INT);
If the command line is mysql –force –one-database db1, mysql handles the input as follows:
• The DELETE statement is executed because the default database is db1, even though the
statement names a table in a different database.

• The DROP TABLE and CREATE TABLE statements are not executed because the default
database is not db1, even though the statements name a table in db1.
• The INSERT and CREATE TABLE statements are executed because the default database is
db1, even though the CREATE TABLE statement names a table in a different database.
• –pager[=command]
Use the given command for paging query output. If the command is omitted, the default pager
is the value of your PAGER environment variable. Valid pagers are less, more, cat [> filename],
and so forth. This option works only on Unix and only in interactive mode. To disable paging,
use –skip-pager. the section called “MYSQL COMMANDS”, discusses output paging further.

• –password[=password], -p[password]
The password to use when connecting to the server. If you use the short option form (-p), you
cannot have a space between the option and the password. If you omit the password value
following the –password or -p option on the command line, mysql prompts for one.

Specifying a password on the command line should be considered insecure. See Section, “End-User Guidelines for Password Security”. You can use an option file to avoid
giving the password on the command line.

• –pipe, -W
On Windows, connect to the server using a named pipe. This option applies only if the server
supports named-pipe connections.

• –port=port_num, -P port_num
The TCP/IP port number to use for the connection.

• –prompt=format_str
Set the prompt to the specified format. The default is mysql>. The special sequences that the
prompt can contain are described in the section called “MYSQL COMMANDS”.

The connection protocol to use for connecting to the server. It is useful when the other
connection parameters normally would cause a protocol to be used other than the one you want.
For details on the permissible values, see Section 4.2.2, “Connecting to the MySQL Server”.

• –quick, -q
Do not cache each query result, print each row as it is received. This may slow down the server
if the output is suspended. With this option, mysql does not use the history file.

• –raw, -r
For tabular output, the “boxing” around columns enables one column value to be distinguished
from another. For nontabular output (such as is produced in batch mode or when the –batch or
–silent option is given), special characters are escaped in the output so they can be identified
easily. Newline, tab, NUL, and backslash are written as \n, \t, \0, and \\. The –raw option
disables this character escaping.

The following example demonstrates tabular versus nontabular output and the use of raw mode
to disable escaping:

% mysql

mysql> SELECT CHAR(92);
| CHAR(92) |
| \ |
% mysql -s
mysql> SELECT CHAR(92);
% mysql -s -r
mysql> SELECT CHAR(92);
• –reconnect
If the connection to the server is lost, automatically try to reconnect. A single reconnect attempt
is made each time the connection is lost. To suppress reconnection behavior, use –skip-

• –safe-updates, –i-am-a-dummy, -U
Permit only those UPDATE and DELETE statements that specify which rows to modify by
using key values. If you have set this option in an option file, you can override it by using —
safe-updates on the command line. See the section called “MYSQL TIPS”, for more
information about this option.

• –secure-auth
Do not send passwords to the server in old (pre-4.1.1) format. This prevents connections except
for servers that use the newer password format.

• –show-warnings
Cause warnings to be shown after each statement if there are any. This option applies to
interactive and batch mode.

• –sigint-ignore
Ignore SIGINT signals (typically the result of typing Control+C).

• –silent, -s
Silent mode. Produce less output. This option can be given multiple times to produce less and
less output.

This option results in non tabular output format and escaping of special characters. Escaping
may be disabled by using raw mode; see the description for the –raw option.

• –skip-column-names, -N
Do not write column names in results.

• –skip-line-numbers, -L
Do not write line numbers for errors. Useful when you want to compare result files that include
error messages.

• –socket=path, -S path
For connections to localhost, the Unix socket file to use, or, on Windows, the name of the
named pipe to use.

• –ssl*
Options that begin with –ssl specify whether to connect to the server using SSL and indicate
where to find SSL keys and certificates. See Section, “SSL Command Options”.

• –table, -t
Display output in table format. This is the default for interactive use, but can be used to produce
table output in batch mode.

• –tee=file_name
Append a copy of output to the given file. This option works only in interactive mode. the
section called “MYSQL COMMANDS”, discusses tee files further.

• –unbuffered, -n
Flush the buffer after each query.

• –user=user_name, -u user_name
The MySQL user name to use when connecting to the server.

• –verbose, -v
Verbose mode. Produce more output about what the program does. This option can be given
multiple times to produce more and more output. (For example, -v -v -v produces table output
format even in batch mode.)

• –version, -V
Display version information and exit.

• –vertical, -E
Print query output rows vertically (one line per column value). Without this option, you can
specify vertical output for individual statements by terminating them with \G.

• –wait, -w
If the connection cannot be established, wait and retry instead of aborting.

• –xml, -X
Produce XML output.

Prior to MySQL 5.1.12, there was no differentiation in the output when using this option
between columns containing the NULL value and columns containing the string literal ‘NULL’;
both were represented as
Beginning with MySQL 5.1.12, the output when –xml is used with mysql matches that of
mysqldump –xml. See mysqldump(1) for details.
Beginning with MySQL 5.1.18, the XML output also uses an XML namespace, as shown here:

shell> mysql –xml -uroot -e “SHOW VARIABLES LIKE ‘version%'”


Source distribution



(See Bug #25946.)
You can also set the following variables by using –var_name=value. The –set-variable format
is deprecated and is removed in MySQL 5.5.
• connect_timeout
The number of seconds before connection timeout. (Default value is 0.)

• max_allowed_packet
The maximum packet length to send to or receive from the server. (Default value is 16MB.)

• max_join_size
The automatic limit for rows in a join when using –safe-updates. (Default value is 1,000,000.)

• net_buffer_length
The buffer size for TCP/IP and socket communication. (Default value is 16KB.)

• select_limit
The automatic limit for SELECT statements when using –safe-updates. (Default value is

For more information type “man mysql”.


[LIKE ‘pattern’ | WHERE expr]
SHOW DATABASES lists the databases on the MySQL server host. SHOW SCHEMAS is
a synonym for SHOW DATABASES as of MySQL 5.0.2. The LIKE clause, if present,
indicates which database names to match. The WHERE clause can be given to select rows
using more general conditions, as discussed in Section 19.18, “Extensions
to SHOW Statements”.
You see only those databases for which you have some kind of privilege, unless you have the
global SHOW DATABASES privilege. You can also get this list using
the mysqlshow command.
If the server was started with the –skip-show-database option, you cannot use this statement at
all unless you have the SHOW DATABASES privilege.
MySQL implements databases as directories in the data directory, so this statement simply lists
directories in that location. However, the output may include names of directories that do not
correspond to actual databases.

USE Syntax
USE db_name
The USE db_name statement tells MySQL to use the db_name database as the default
(current) database for subsequent statements. The database remains the default until the end of
the session or another USE statement is issued.

SHOW [FULL] TABLES [{FROM | IN} db_name]
[LIKE ‘pattern’ | WHERE expr]
SHOW TABLES lists the non-TEMPORARY tables in a given database. You can also get
this list using the mysqlshowdb_name command. The LIKE clause, if present, indicates
which table names to match. The WHERE clause can be given to select rows using more
general conditions, as discussed in Section 19.18, “Extensions to SHOWStatements”.
Matching performed by the LIKE clause is dependent on the setting of
the lower_case_table_names system variable.
Before MySQL 5.0.1, the output from SHOW TABLES contains a single column of table
names. Beginning with MySQL 5.0.1, this statement also lists any views in the database. As of
MySQL 5.0.2, the FULL modifier is supported such that SHOW FULL TABLES displays a
second output column. Values for the second column areBASE TABLE for a table
and VIEW for a view.
If you have no privileges for a base table or view, it does not show up in the output from SHOW
TABLES ormysqlshow db_name.



select_expr [, select_expr …]
[FROM table_references
[WHERE where_condition]
[GROUP BY {col_name | expr | position}
[HAVING where_condition]
[ORDER BY {col_name | expr | position}
[ASC | DESC], …]
[LIMIT {[offset,] row_count | row_count OFFSET offset}]
[PROCEDURE procedure_name(argument_list)]
[INTO OUTFILE ‘file_name’ export_options
| INTO DUMPFILE ‘file_name’
| INTO var_name [, var_name]]
SELECT is used to retrieve rows selected from one or more tables, and can include UNION
statements and subqueries. See Section, “UNION Syntax”, and Section 13.2.9,
“Subquery Syntax”.

The most commonly used clauses of SELECT statements are these:

Each select_expr indicates a column that you want to retrieve. There must be at least one

table_references indicates the table or tables from which to retrieve rows. Its syntax is described
in Section, “JOIN Syntax”.

The WHERE clause, if given, indicates the condition or conditions that rows must satisfy to be
selected. where_condition is an expression that evaluates to true for each row to be selected.
The statement selects all rows if there is no WHERE clause.

In the WHERE expression, you can use any of the functions and operators that MySQL
supports, except for aggregate (summary) functions. See Section 9.5, “Expression Syntax”, and
Chapter 12, Functions and Operators.

SELECT can also be used to retrieve rows computed without reference to any table.

For example:

mysql> SELECT 1 + 1;
-> 2
You are permitted to specify DUAL as a dummy table name in situations where no tables are

mysql> SELECT 1 + 1 FROM DUAL;
-> 2
DUAL is purely for the convenience of people who require that all SELECT statements should
have FROM and possibly other clauses. MySQL may ignore the clauses. MySQL does not
require FROM DUAL if no tables are referenced.

In general, clauses used must be given in exactly the order shown in the syntax description. For
example, a HAVING clause must come after any GROUP BY clause and before any ORDER
BY clause. The exception is that the INTO clause can appear either as shown in the syntax
description or immediately following the select_expr list. For more information about INTO,
see Section, “SELECT … INTO Syntax”.

The list of select_expr terms comprises the select list that indicates which columns to retrieve.
Terms specify a column or expression or can use *-shorthand:

A select list consisting only of a single unqualified * can be used as shorthand to select all
columns from all tables:

tbl_name.* can be used as a qualified shorthand to select all columns from the named table:

SELECT t1.*, t2.* FROM t1 INNER JOIN t2 …
Use of an unqualified * with other items in the select list may produce a parse error. To avoid
this problem, use a qualified tbl_name.* reference

SELECT AVG(score), t1.* FROM t1 …
The following list provides additional information about other SELECT clauses:

A select_expr can be given an alias using AS alias_name. The alias is used as the expression’s
column name and can be used in GROUP BY, ORDER BY, or HAVING clauses. For example:

SELECT CONCAT(last_name,’, ‘,first_name) AS full_name
FROM mytable ORDER BY full_name;
The AS keyword is optional when aliasing a select_expr with an identifier. The preceding
example could have been written like this:

SELECT CONCAT(last_name,’, ‘,first_name) full_name
FROM mytable ORDER BY full_name;
However, because the AS is optional, a subtle problem can occur if you forget the comma
between two select_expr expressions: MySQL interprets the second as an alias name. For
example, in the following statement, columnb is treated as an alias name:

SELECT columna columnb FROM mytable;
For this reason, it is good practice to be in the habit of using AS explicitly when specifying
column aliases.

It is not permissible to refer to a column alias in a WHERE clause, because the column value
might not yet be determined when the WHERE clause is executed. See Section B.5.5.4,
“Problems with Column Aliases”.

The FROM table_references clause indicates the table or tables from which to retrieve rows.
If you name more than one table, you are performing a join. For information on join syntax,
see Section, “JOIN Syntax”. For each table specified, you can optionally specify an

tbl_name [[AS] alias] [index_hint]
The use of index hints provides the optimizer with information about how to choose indexes
during query processing. For a description of the syntax for specifying these hints, see Section, “Index Hint Syntax”.

You can use SET max_seeks_for_key=value as an alternative way to force MySQL to prefer
key scans instead of table scans. See Section 5.1.4, “Server System Variables”.

You can refer to a table within the default database as tbl_name, or as db_name.tbl_name to
specify a database explicitly. You can refer to a column as col_name, tbl_name.col_name, or
db_name.tbl_name.col_name. You need not specify a tbl_name or db_name.tbl_name prefix
for a column reference unless the reference would be ambiguous. See Section 9.2.1, “Identifier
Qualifiers”, for examples of ambiguity that require the more explicit column reference forms.

A table reference can be aliased using tbl_name AS alias_name or tbl_name alias_name:

SELECT, t2.salary FROM employee AS t1, info AS t2

SELECT, t2.salary FROM employee t1, info t2
Columns selected for output can be referred to in ORDER BY and GROUP BY clauses using
column names, column aliases, or column positions. Column positions are integers and begin
with 1:

SELECT college, region, seed FROM tournament
ORDER BY region, seed;

SELECT college, region AS r, seed AS s FROM tournament
ORDER BY r, s;

SELECT college, region, seed FROM tournament
ORDER BY 2, 3;
To sort in reverse order, add the DESC (descending) keyword to the name of the column in the
ORDER BY clause that you are sorting by. The default is ascending order; this can be specified
explicitly using the ASC keyword.

If ORDER BY occurs within a subquery and also is applied in the outer query, the outermost
ORDER BY takes precedence. For example, results for the following statement are sorted in
descending order, not ascending order:

Use of column positions is deprecated because the syntax has been removed from the SQL

If you use GROUP BY, output rows are sorted according to the GROUP BY columns as if
you had an ORDER BY for the same columns. To avoid the overhead of sorting that GROUP
BY produces, add ORDER BY NULL:


MySQL extends the GROUP BY clause so that you can also specify ASC and DESC after
columns named in the clause:

MySQL extends the use of GROUP BY to permit selecting fields that are not mentioned in the
GROUP BY clause. If you are not getting the results that you expect from your query, please
read the description of GROUP BY found in Section 12.15, “Functions and Modifiers for Use
with GROUP BY Clauses”.

GROUP BY permits a WITH ROLLUP modifier. See Section 12.15.2, “GROUP BY

The HAVING clause is applied nearly last, just before items are sent to the client, with no
optimization. (LIMIT is applied after HAVING.)

A HAVING clause can refer to any column or alias named in a select_expr in the SELECT list
or in outer subqueries, and to aggregate functions. However, the SQL standard requires that
HAVING must reference only columns in the GROUP BY clause or columns used in aggregate
functions. To accommodate both standard SQL and the MySQL-specific behavior of being
able to refer columns in the SELECT list, MySQL 5.0.2 and up permit HAVING to refer to
columns in the SELECT list, columns in the GROUP BY clause, columns in outer subqueries,
and to aggregate functions.

For example, the following statement works in MySQL 5.0.2 but produces an error for earlier

mysql> SELECT COUNT(*) FROM t GROUP BY col1 HAVING col1 = 2;
If the HAVING clause refers to a column that is ambiguous, a warning occurs. In the following
statement, col2 is ambiguous because it is used as both an alias and a column name:

SELECT COUNT(col1) AS col2 FROM t GROUP BY col2 HAVING col2 = 2;
Preference is given to standard SQL behavior, so if a HAVING column name is used both in
GROUP BY and as an aliased column in the output column list, preference is given to the
column in the GROUP BY column.

Do not use HAVING for items that should be in the WHERE clause. For example, do not write
the following:

SELECT col_name FROM tbl_name HAVING col_name > 0;
Write this instead:

SELECT col_name FROM tbl_name WHERE col_name > 0;
The HAVING clause can refer to aggregate functions, which the WHERE clause cannot:

SELECT user, MAX(salary) FROM users
GROUP BY user HAVING MAX(salary) > 10;
(This did not work in some older versions of MySQL.)

MySQL permits duplicate column names. That is, there can be more than one select_expr with
the same name. This is an extension to standard SQL. Because MySQL also permits GROUP
BY and HAVING to refer to select_expr values, this can result in an ambiguity:

In that statement, both columns have the name a. To ensure that the correct column is used for
grouping, use different names for each select_expr.

MySQL resolves unqualified column or alias references in ORDER BY clauses by searching
in the select_expr values, then in the columns of the tables in the FROM clause. For GROUP
BY or HAVING clauses, it searches the FROM clause before searching in the select_expr
values. (For GROUP BY and HAVING, this differs from the pre-MySQL 5.0 behavior that
used the same rules as for ORDER BY.)

The LIMIT clause can be used to constrain the number of rows returned by the SELECT
statement. LIMIT takes one or two numeric arguments, which must both be nonnegative integer
constants (except when using prepared statements).

With two arguments, the first argument specifies the offset of the first row to return, and the
second specifies the maximum number of rows to return. The offset of the initial row is 0 (not

SELECT * FROM tbl LIMIT 5,10; # Retrieve rows 6-15
To retrieve all rows from a certain offset up to the end of the result set, you can use some large
number for the second parameter. This statement retrieves all rows from the 96th row to the

SELECT * FROM tbl LIMIT 95,18446744073709551615;
With one argument, the value specifies the number of rows to return from the beginning of the
result set:

SELECT * FROM tbl LIMIT 5; # Retrieve first 5 rows
In other words, LIMIT row_count is equivalent to LIMIT 0, row_count.

For prepared statements, you can use placeholders (supported as of MySQL version 5.0.7). The
following statements will return one row from the tbl table:

SET @a=1;
The following statements will return the second to sixth row from the tbl table:

SET @skip=1; SET @numrows=5;
EXECUTE STMT USING @skip, @numrows;
For compatibility with PostgreSQL, MySQL also supports the LIMIT row_count OFFSET
offset syntax.

If LIMIT occurs within a subquery and also is applied in the outer query, the outermost LIMIT
takes precedence. For example, the following statement produces two rows, not one:

A PROCEDURE clause names a procedure that should process the data in the result set. For
an example, see Section 8.8.2, “Using PROCEDURE ANALYSE”, which describes
ANALYSE, a procedure that can be used to obtain suggestions for optimal column data types
that may help reduce table sizes.

The SELECT … INTO form of SELECT enables the query result to be written to a file or stored
in variables. For more information, see Section, “SELECT … INTO Syntax”.

If you use FOR UPDATE with a storage engine that uses page or row locks, rows examined
by the query are write-locked until the end of the current transaction. Using LOCK IN SHARE
MODE sets a shared lock that permits other transactions to read the examined rows but not to
update or delete them. See Section, “SELECT … FOR UPDATE and SELECT …
LOCK IN SHARE MODE Locking Reads”.

Following the SELECT keyword, you can use a number of options that affect the operation of
the statement. HIGH_PRIORITY, STRAIGHT_JOIN, and options beginning with SQL_ are
MySQL extensions to standard SQL.

The ALL and DISTINCT options specify whether duplicate rows should be returned. ALL
(the default) specifies that all matching rows should be returned, including duplicates.
DISTINCT specifies removal of duplicate rows from the result set. It is an error to specify both
options. DISTINCTROW is a synonym for DISTINCT.

HIGH_PRIORITY gives the SELECT higher priority than a statement that updates a table.
You should use this only for queries that are very fast and must be done at once. A SELECT
HIGH_PRIORITY query that is issued while the table is locked for reading runs even if there
is an update statement waiting for the table to be free. This affects only storage engines that
use only table-level locking (such as MyISAM, MEMORY, and MERGE).

HIGH_PRIORITY cannot be used with SELECT statements that are part of a UNION.

STRAIGHT_JOIN forces the optimizer to join the tables in the order in which they are listed
in the FROM clause. You can use this to speed up a query if the optimizer joins the tables in
nonoptimal order. STRAIGHT_JOIN also can be used in the table_references list. See Section, “JOIN Syntax”.

STRAIGHT_JOIN does not apply to any table that the optimizer treats as a const or system
table. Such a table produces a single row, is read during the optimization phase of query
execution, and references to its columns are replaced with the appropriate column values before
query execution proceeds. These tables will appear first in the query plan displayed by
EXPLAIN. See Section 8.2.1, “Optimizing Queries with EXPLAIN”. This exception may not
apply to const or system tables that are used on the NULL-complemented side of an outer join
(that is, the right-side table of a LEFT JOIN or the left-side table of a RIGHT JOIN.

to tell the optimizer that the result set has many rows or is small, respectively. For
SQL_BIG_RESULT, MySQL directly uses disk-based temporary tables if needed, and prefers
sorting to using a temporary table with a key on the GROUP BY elements. For

SQL_SMALL_RESULT, MySQL uses fast temporary tables to store the resulting table instead
of using sorting. This should not normally be needed.

SQL_BUFFER_RESULT forces the result to be put into a temporary table. This helps MySQL
free the table locks early and helps in cases where it takes a long time to send the result set to
the client. This option can be used only for top-level SELECT statements, not for subqueries
or following UNION.

SQL_CALC_FOUND_ROWS tells MySQL to calculate how many rows there would be in
the result set, disregarding any LIMIT clause. The number of rows can then be retrieved with
SELECT FOUND_ROWS(). See Section 12.13, “Information Functions”.

The SQL_CACHE and SQL_NO_CACHE options affect caching of query results in the query
cache (see Section 8.6.3, “The MySQL Query Cache”). SQL_CACHE tells MySQL to store
the result in the query cache if it is cacheable and the value of the query_cache_type system
variable is 2 or DEMAND. With SQL_NO_CACHE, the server does not use the query cache.
It neither checks the query cache to see whether the result is already cached, nor does it cache
the query result. (Due to a limitation in the parser, a space character must precede and follow
the SQL_NO_CACHE keyword; a nonspace such as a newline causes the server to check the
query cache to see whether the result is already cached.)

For a query that uses UNION, subqueries, or views, the following rules apply:

SQL_NO_CACHE applies if it appears in any SELECT in the query.

For a cacheable query, SQL_CACHE applies if it appears in the first SELECT of the query, or
in the first SELECT of a view referred to by the query.

To import SQL query to the file use:


The file can be copied from SQL Server host using command “scp” discussed earlier.

APPENDIX M – SageMath commands / reference

Go to your Kali Linux environment.

Go to the SageMath directory: cd /bin/SageMath

Run SageMath: ./sage

Reference documentation:

Thematic tutorials:

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