Wednesday, September 30, 2015
ETHICAL HACKER INTRO
ETHICAL
HACKING INTRODUCTION
DEFEND YOUR NETWORK AGAINST HACKERS…..
MASTER THE HACKING TECHNOLOGIES…….
BECOME AN ETHICAL HACKER…….
An ethical hacker is a computer and networking
expert who systematically attempts to gain access to a computer system or network on behalf of its owners for the
purpose of finding security vulnerabilities that a
spiteful hacker could potentially utilize
We must know the way of hacking before being
an ethical hacker
O/S Hacking
Remote Connectivity and VoIP Hacking .
Network Devices Hacking. . . . . . . . . . .
. . . . . . .
Wireless Hacking .
Hacking Code . .
Web Hacking
Ports Hacking and many more….
Hacking applications
Hacking the Users
Hacking the Databases and Storage Systems
Password Cracking
MEMORY MANAGEMENT - 3
MEMORY MANAGEMENT INTERVIEW QUESTIONS AND ANSWERS
PAGE - 3
PAGE - 3
21..How
to check the current shared memory pages on the system?
#
ipcs –m
22..Where the kernel load in to
the system to run linux?
memory
23..How to see the memory usage
in percentage?
# free | sed -n ‘2p’ | gawk ‘x = ($3 /$2)
{print x}’
24..How to find out all the process of the system along with their process states?
# ps -al
25..How to find the current virtual memory
status on your system?
# cat
/proc/meminfo
26..Explain
about Environment Variables?
The bash shell uses a feature called environment
variables to store information
about the shell session and the working
environment . This feature also allows you to store data in memory that can be easily accessed by any program or
script running from the shell.
27..How to check the extract CPU and memory information about your system?
# uptime
28..How
to extracting system memory information?
#
vmstat
MEMORY MANAGEMENT - 2
MEMORY MANAGEMENT INTERVIEW QUESTIONS AND ANSWERS
PAGE - 2
PAGE - 2
11..How to manage the data segment?
Linux systems historically have provided interfaces
for directly managing the data segment. However, most programs have no direct
use for these interfaces because malloc( ) and other allocation schemes are
easier to use and more powerful
12..How to create the anonymous memory mappings?
Use of a memory
mapping over the heap for a specific allocation, or perhaps because you are
writing your own memory allocation system, you may want to manually create your
own anonymous memory mapping—either, way, Linux makes it easy.
13..How to debugging
memory allocations?
Programs can
set the environment variable MALLOC_CHECK_ to enable enhanced debugging in the
memory subsystem. The additional debugging checks come at the expense of less
efficient memory allocations, but the overhead is often worth it during the
debugging stage of application development. You can check with the following
command
$ MALLOC_CHECK_=1 ./rudder
14..How
to lock the virtual memory?
A call to mlock( ) locks the virtual memory starting at addr, and
extending for
Len bytes into physical memory.
15..How to lock the all address space?
A call to
mlockall( ) locks all of the pages in the current process’ address space into physical
memory.
16..How to unlock the memory?
The system call
munlock( ) unlocks the pages starting at addr and extending for len bytes. It
undoes the effects of mlock( ).
17..How to find out the page is physical
memory or not?
Linux provides
the mincore( ) function, which can be used to determine whether a given range
of memory is in physical memory, or swapped out to disk:
#include
<unistd.h>
#include
<sys/mman.h>
int mincore
(void *start,
size_t length,
unsigned char
*vec);
A call to
mincore( ) provides a vector delineating which pages of a mapping are in physical
memory at the time of the system call. The call returns the vector via vec, and
describes the pages starting at start
and extending for length bytes.
Each byte in
vec corresponds to one page in the range provided, starting with the first byte
describing the first page, and moving linearly forward. Consequently, vec must
be at least large enough to contain (length - 1 + page size) / page
size bytes. The lowest-order bit in each byte is 1 if the page is resident
in physical memory, and 0 if it is not. The other bits are currently undefined
and reserved for future use.
18..What
is Min / Max Spare Servers?
These options
are used to create a pool of spare servers that Apache can use
when it is busy.
Larger sites may wish to increase these numbers from their defaults. However,
for each spare server, more memory is required on the server.
19..What
is memory optimizations?
User-space code
and data, kernel code and data reside permanently in main
memory, so it
is important to reduce memory waste in every way possible. Initialization code
is a good candidate for memory optimization. Given their nature, most
initialization routines are executed either just once or not at all, depending
on the kernel configuration
20..What is System Memory Management?
One of the primary functions of the operating
system kernel is memory management. Not only does the kernel manage the physical
memory available on the server, but it can also create and manage virtual
memory, or memory that does not actually exist.
It does this by using space on the hard disk,
called the swap space. The kernel swaps the contents of virtual memory locations
back and forth from the swap space to the actual physical memory. This allows
the system to think there is more memory available than what physically exists
MEMORY MANAGEMENT - 1
MEMORY MANAGEMENT INTERVIEW QUESTIONS AND ANSWERS
PAGE - 1
1..Which
partition is used for virtual memory by a Linux system?
swap
2..How to find
out the usage of memory in linux?
# free –m
# vmstat –s
# top
3..What is Swap Space?
Swap space in
Linux is used when the amount of physical memory (RAM) is full. If the system needs
more memory resources and the RAM is full, inactive pages in memory are moved
to the swap space. While swap space can help machines with a small amount of
RAM, it should not be considered a replacement for more RAM. Swap space is
located on hard drives, which have a slower access time than physical memory.
4..How
to check the information about RAM of your system?
# free
5..What
is virtual address space?
Linux, a
operating system, virtualizes its physical resource of memory.
Processes do
not directly address physical memory. Instead, the kernel associates each process
with a unique virtual address space. This address space is linear, with addresses
starting at zero, and increasing to some maximum value.
6..Write the difference between the Pages
and Paging?
The virtual
address space is composed of pages. The system
architecture and
machine type
determine the size of a page, which is fixed; typical sizes include 4 KB (for
32-bit systems), and 8 KB (for 64-bit systems).* Pages are either valid or
invalid.
A valid page is associated with a page
in physical memory, or some secondary backing storage, such as a swap partition
or a file on disk. An invalid page is not associated with anything and
represents an unused, unallocated piece of the address space.
Accessing such
a page causes a segmentation violation. The address space is not necessarily contiguous. While linearly addressed, it
contains plenty of unaddressable gaps.
7..What is memory region?
The kernel
arranges pages into blocks that share certain properties, such as access permissions.
These blocks are called memory regions, segments, or mappings.
8..How
to allocate dynamic memory?
Memory also
comes in the form of automatic and static variables, but the foundation of any
memory management system is the allocation, use, and eventual return of dynamic
memory. Dynamic memory is allocated at runtime, not compile time, in sizes
that may be unknown until the moment of allocation
9..How to free the dynamic memory?
Automatic
allocations, which are automatically reaped when the stack
unwinds,
dynamic allocations are permanent parts of the process’ address space until they
are manually freed
10..How to allocate the aligned memory?
Most part, the
compiler and the C library transparently handle alignment
concerns. POSIX
decrees that the memory returned via malloc( ), calloc( ), and
realloc( ) be
properly aligned for use with any of the standard C types. On Linux,
these functions
always return memory that is aligned along an 8 byte boundary on 32-bit systems
and a 16 byte boundary on 64-bit systems.
REMOTE ACCESS - 2
REMOTE ACCESS INTERVIEW QUESTIONS AND ANSWERS
PAGE - 2
PAGE - 2
11..How to connect the binary
mode in ftp?
ftp> binary The FTP
12..How to send the particular file in ftp?
ftp>
put source_name
13..How to find out the local directory?
ftp> lpwd.
14..How to copy the particular file in ftp?
ftp> get source_file_name target_file_name
15..How to use FTP
mget without prompt?
ftp -i
hostname
( Use the
-i when starting the ftp and it will turn that off )
16..How can I transfer a
group of files without typing all their names?
The asterisk (
*) is a wildcard that tells FTP to match all files starting with fi
17..How to upload the file in ftp?
ftp>
put file_name
18..How to logout from
ftp connection?
ftp> bye
or
ftp> quit
REMOTE ACCESS - 1
REMOTE ACCESS INTERVIEW QUESTIONS AND ANSWERS
PAGE - 1
PAGE - 1
1..What
is ssh?
Connecting to another machine on the Internet
is a risky proposition. Some tools, like ftp and telnet, that provide access to
another machine transmit the username and password in clear text
SSH is one such program. It's name is an
acronym for “Secure SHell”. SSH has to run both on the machine you're
using and the machine you're connecting
to SSH runs on the remote machine just
like any other Linux service, and is initiated by you on the client in order to
connect to the remote machine
2..How
to connect the remote system using ssh?
SSH (the server) must be running on the
remote machine, and you need to know the IP address or URL of the remote
machine. The remote machine needs to be able to accept requests on port 22, the
port used by SSH.
3..How
to use the public/private keys to
connect the remote server?
Public key authentication involves a pair of
related keys that in this situation take the form of text files. The public key
sits on the remote machine while the private key resides on the local machine. When the local machine connects to
the remote box, the two keys are matched up by the remote machine. If they
match correctly, the authentication passes and you are granted access.
4...How
to create public and private keys?
ssh-keygen -t rsa
5..What
is the use of ftp?
The File Transfer Protocol (FTP) is a standard network protocol used to
transfer computer files from
one host to
another host over a TCP-based network, such as the Internet
6..Explain ssh client?
There are n
number of ssh client programs: slogin, scp, and ssh.
They each read the same configuration file, usually called /etc/openssh/ssh_config
7..How many types of the file available
in ftp?
There
are two types of files. An ASCII file contains text; a binary file contains
other kinds of information (such as graphics, audio recordings, or compressed
text).
8..How to connect the ascii mode?
ftp>
ascii
9..How
to copy the particular file in ftp?
ftp>
get source_name
10..How to see the list of files in ftp?
ftp>
ls
MAIL Q & A PAGE - 2
MAIL INTERVIEW QUESTIONS AND ANSWERS
PAGE - 2
PAGE - 2
11..How
to make copy of the all mails from mydomain.com
received by user1 ?
vi
/etc/mail/virtusertable @mydomain.com user1
:wq!
# service
sendmail restart
12..How
to make copy of the all mails from mydomain.com
received by user1 ?
vi
/etc/mail/virtusertable @mydomain.com user1
:wq!
# service sendmail
restart
13..
How to manage the mail spool?
Mail is queued
in the /var/spool/mqueue
directory before beingtransmitted. This
directory is
called the mail spool. The sendmail program
provides the mailq
command as a means of displayinga formatted list
of all spooled mail messages and their status. The /usr/bin/mailq command is a symbolic link to the sendmail executable
and behaves identically to:
# sendmail –bp
14.. What is
mail Statistics?
sendmail collects
data on the volume of mail traffic and some information on the
hosts to which
it has delivered mail. There are two commands available to display this
information, mailstats
and hoststat.
15..What is the use of mailstats command?
The mailstats
command displays statistics on the volume of mail processed by sendmail.
MAIL Q & A PAGE - 1
MAIL INTERVIEW QUESTIONS AND ANSWERS
PAGE - 1
PAGE - 1
1..What
is E-Mail?
Electronic mail
transport has been one of the most prominent uses of networking
since networks
were devised. Email started as a simple service that copied a file from one
machine to another and appended it to the recipient’s mailbox file. The
concept remains the same, although an ever-growing net, with its complex
routing requirements and its ever increasing
load of messages, has made a more elaborate scheme necessary
2..Explain
the meaning of mail message?
A mail message
generally consists of a message body, which is the text of the message, and
special administrative data specifying recipients, transport medium, etc, similar
to what you see when you look at a physical letter’s envelope.
3..Explain the mail delivery process?
We will compose
mail usinga program such as mail or mailx, or more
sophisticated
ones such as mutt, tkrat, or pine. These programs are
called mail user agents (MUAs). If you send a mail message, the
interface program will in most cases hand it to another program for delivery.
This is called the mail transport agent (MTA) Mail delivered over a network
using TCP/IP commonly uses Simple Mail Transfer Protocol (SMTP)
4..Explain the Mail routing process?
The process of
directing a message to the recipient’s host is called routing. Apart
from finding a
path from the sending site to the destination, it involves error checking and
may involve speed and cost optimization.
On the
Internet, the main job of directing data to the recipient host (once it is
known by its IP address) is done by the IP networking layer.
5..What
is the use of mailertable?
The mailertable feature adds support to the sendmail configuration
for the
mailertable. The
syntax of the mailertable
feature is:FEATURE(`mailertable', `specification')
6..Explain the use of virtusertable?
The send mail virtue
table feature adds support for the virtual user table,
where virtual email hosting is configured. Virtual email hosting allows the
mail server to accept and deliver mail on behalf of a number of different
domains as though it were a number of separate mail hosts
7..E-Mail function explain?
Sending mail via SMTP
(Simple Mail Transfer Protocol) and receiving mail from an ISP's POP (Post Office
Protocol) server, you can use a desktop client like Netscape Communicator or
KDE kmail. You will need to enter the names of the SMTP and POP servers in the
preferences of the respective application, as well as your E−mail address
(e.g., username@example.com), and your dial−up password. The same applies to
Usenet News. Enter the name of the NNTP (Network News Transfer Protocol) server
in your News client's preferences section. You may also have to provide the IP
addresses of the ISP's primary and secondary name servers.
If you have a traditional MTA (Mail Transport
Agent) like Sendmail, Smail, qmail, You'll
need to follow the instructions in each package. Basically, configuration
entails determining which host machine, either on your local LAN or via dial−up
Internet, is the ``Smart Host,'' if you're using SMTP. If you're using the older UUCP protocol, then you'll
need to consult the directions for configuring UUCP, and also make sure that
your ISP's system is configured to relay mail to you.
8..What does mean an open mail relay server?
An Open mail relay server, means that this is
a server that everyone can send emails through it without the need to identify
first or be a part of the domain group
9..What is the purpose of an exim service on
a server?
The exim service is an SMTP service
that can replace the regular sendmail service that comes with the Linux
installation
10..How can you check the mail queue of an
exim mail server?
# mailq
SAMBA Q & A PAGE - 1
SAMBA INTERVIEW QUESTIONS AND ANSWERS
PAGE - 1
10..How to take the print from window to shared printer in linux server?
PAGE - 1
1..What is Samba?
Samba is a suite of Unix applications that speak the SMB (Server
Message Block) protocol. Many operating systems, including Windows and OS/2,
use SMB to perform client-server networking. By supporting this protocol, Samba
allows Unix servers to get in on the action, communicating with the same
networking protocol as Microsoft Windows products.
2..What is SWAT?
Samba Web Administration Tool (SWAT) is used to
simplify administration and configuration of Samba
3..How
to prevent the browsing?
You can restrict a share from being in a browse list by using the browseable option.
This boolean option prevents a share from being seen in the Network
Neighborhood at all. For example, to prevent the[data] share from the
previous chapter from being visible, we could write:
[data]
path = /home/samba/data
browseable = no
guest ok = yes
comment = Data Drive
volume = Sample-Data-Drive
writeable = yes
4..What
is the use of samba?
You don't want to pay for -
or can't afford - a full-fledged Windows NT server, yet you still need the
functionality that one provides.
You want
to provide a common area for data or user directories in order to transition
from a Windows server to a linux one, or vice versa.
You want
to be able to share printers across both Windows and linux workstations.
You want
to be able to access NT files from a linux server.
5..How Can I Get Samba?
Samba is available in
both binary and source format from a set of mirror sites across the Internet.
The primary home site for Samba is located at http://www.samba.org/.
6..How to install samba?
# yum -y install samba
7..What are the SAMBA server Types ?
Primary Domain Controller (PDC)
Backup Domain Controller (BDC)
ADS Domain Controller
Backup Domain Controller (BDC)
ADS Domain Controller
8..How to find out the users currently locked to the files?
#
smbstatus
9..What is the use of "smbclient"
command?
"smbclient" is used to display the list of shares on
your server.
smbclient -L localhost –N
10..How to take the print from window to shared printer in linux server?
vi
/etc/samba/smb.conf [global]
netbios name=station? workgroup =
mygroup
server string=Share from Linux Server
security=user
smb passwd file=/etc/samba/smbpasswd
encrypt passwords=yes
[data]
path=/data
writable=yes
public=no
browsable=yes
valid
users=user1 user2
smbpasswd –a user1
smbpasswd –a user2
service smb start |
restart
chkconfig smb on
Samba
servers helps to share the data between linux and windows. Configuration file
is /etc/samba/smb.conf. There are some pre-defined section, i. global -> use
to define the global options, ii. Printers -> use to share the printers,
iii. homes - > use the share the user’s home directory.
/etc/printcap/ file containts all installed printer name
Subscribe to:
Posts (Atom)