How to Repair Boot-Loader In Ubuntu

Boot-Repair is a simple tool to repair frequent boot issues you may encounter in Ubuntu like when you can't boot Ubuntu after installing Windows or another Linux distribution, or when you can't boot Windows after installing Ubuntu, or when GRUB is not displayed anymore, some upgrade breaks GRUB, etc.

Boot-Repair lets you fix these issues with a simple click, which (generally reinstalls GRUB and) restores access to the operating systems you had installed before the issue.

Boot-Repair also has advanced options to backup table partitions, backup bootsectors, create a Boot-Info (to get help by email or forum), or change the default repair parameters: configure GRUB, add kernel options (acpi=off ...), purge GRUB, change the default OS, restore a Windows-compatible MBR, repair a broken filesystem, specify the disk where GRUB should be installed, etc.

Boot-Repair is a free software, licensed under GNU-GPL. Boot-Repair should be soon included in Ubuntu official repositories, until then use it at your own risks.

Getting Boot-Repair

1st option : get a CD including Boot-Repair

The easiest way to use Boot-Repair is to burn one of the following disks and boot on it.

• Boot-Repair is included in Ubuntu-Secure-Remix (multi-languages, ok for Wifi, LVM and RAID, 32 or 64bit, based on Ubuntu 12.10, Boot-Repair shortcut in the desktop, the 64bit version is UEFI-compatible)
• Boot-Repair-Disk is a CD starting Boot-Repair automatically. Both 32&64bit and only 360Mo, but: English only, no Wifi, no LVM, no RAID.

Remark : you can also install the ISO on a live-USB (eg via UnetBootin or LiliUSB).

2nd option : install Boot-Repair in Ubuntu

- boot your computer on a Ubuntu live-CD or live-USB.

- choose "Try Ubuntu"

- connect internet

- open a new Terminal, then type:

sudo add-apt-repository ppa:yannubuntu/boot-repair && sudo apt-get update

- Press Enter.

- Then type:

sudo apt-get install -y boot-repair && boot-repair

- Press Enter

Using Boot-Repair

Recommended repair

• launch Boot-Repair from either :
  • the Dash (the Ubuntu logo at the top-left of the screen)
  • or System->Administration->Boot-Repair menu (Ubuntu 10.04 only)
  • or by typing 'boot-repair' in a terminal
• Then click the "Recommended repair" button. When repair is finished, note the URL (paste.ubuntu.com/XXXXX) that appeared on a paper, then reboot and check if you recovered access to your OSs.
• If the repair did not succeed, indicate the URL to people who help you by email or forum.

Advanced options

Warning: the default settings are the ones used by the "Recommended Repair". Changing them may worsen your problem. Don't modify them before creating a BootInfo URL, and asking advice on this thread.

Keep Rocking! Keep Hacking!

How To Change File Permission In Linux

First of all, let's figure out what the command "chmod" does.

chmod - The chmod command allows you to alter access rights to files and directories. All files and directories have security permissions that grant the user particular groups’ or all other users’ access. To view your files' settings, at the shell prompt type: ls -alt
You should see some files with the following in front of them (an example follows):
total 4
drwxrwsr-x 7 file1 file1 1024 Apr 6 14:30 .
drwxr-s--x 22 file2 file2 1024 Mar 30 18:20 ..
d-wx-wx-wx 3 file3 file3 1024 Apr 6 14:30 content
drwxr-xr-x 2 file4 file4 1024 Mar 25 20:43 files

What do the letters mean in front of the files/directories mean?
r indicates that it is readable (someone can view the file’s contents)
w indicates that it is writable (someone can edit the file’s contents)
x indicates that it is executable (someone can run the file, if executable)
- indicates that no permission to manipulate has been assigned.

When listing your files, the first character lets you know whether you’re looking at a file or a directory. It’s not part of the security settings. The next three characters indicate Your access restrictions. The next three indicate your group's permissions, and finally other users' permissions.

Use chmod followed by the permission you are changing. In very simple form this would be:
chmod 755 filename
The example above will grant you full rights, group rights to execute and read, and all others access to execute the file.
# Permission
7 full
6 read and write
5 read and execute
4 read only
3 write and execute
2 write only
1 execute only
0 none

Still confused? Use the table above to define the settings for the three "users." In the command, the first number refers to your permissions, the second refers to group, and the third refers to general users.

Typing the command: chmod 751 filename

gives you full access, the group read and execute, and all others execute only permission.

I hope this article helps anyone having trouble with file permissions on linux. Don't forget to rate and comment. Thanks. 

File Permissions on Linux

First of all, let's figure out what the command "chmod" does.

chmod - The chmod command allows you to alter access rights to files and directories. All files and directories have security permissions that grant the user particular groups’ or all other users’ access. To view your files' settings, at the shell prompt type: ls -alt
You should see some files with the following in front of them (an example follows):
total 4
drwxrwsr-x 7 file1 file1 1024 Apr 6 14:30 .
drwxr-s--x 22 file2 file2 1024 Mar 30 18:20 ..
d-wx-wx-wx 3 file3 file3 1024 Apr 6 14:30 content
drwxr-xr-x 2 file4 file4 1024 Mar 25 20:43 files

What do the letters mean in front of the files/directories mean?
r indicates that it is readable (someone can view the file’s contents)
w indicates that it is writable (someone can edit the file’s contents)
x indicates that it is executable (someone can run the file, if executable)
- indicates that no permission to manipulate has been assigned.

When listing your files, the first character lets you know whether you’re looking at a file or a directory. It’s not part of the security settings. The next three characters indicate Your access restrictions. The next three indicate your group's permissions, and finally other users' permissions.

Use chmod followed by the permission you are changing. In very simple form this would be:
chmod 755 filename
The example above will grant you full rights, group rights to execute and read, and all others access to execute the file.
# Permission
7 full
6 read and write
5 read and execute
4 read only
3 write and execute
2 write only
1 execute only
0 none

Still confused? Use the table above to define the settings for the three "users." In the command, the first number refers to your permissions, the second refers to group, and the third refers to general users.

Typing the command: chmod 751 filename

gives you full access, the group read and execute, and all others execute only permission.

I hope this article helps anyone having trouble with file permissions on linux. Don't forget to rate and comment. Thanks. 

Top 10 Linux Tools

1. nmap - Nmap ("Network Mapper") is a free open source utility for network exploration or 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. Nmap runs on most types of computers and both console and graphical versions are available.

2. Nikto - Nikto is an Open Source (GPL) web server scanner which performs comprehensive tests against web servers for multiple items, including over 3200 potentially dangerous files/CGIs, versions on over 625 servers, and version specific problems on over 230 servers. Scan items and plugins are frequently updated and can be automatically updated (if desired).

3. THC-Amap - Amap is a next-generation tool for assistingnetwork penetration testing. It performs fast and reliable application protocol detection, independant on the TCP/UDP port they are being bound to.

4. Ethereal - Ethereal is used by network professionals around the world for troubleshooting, analysis, software and protocol development, and education. It has all of the standard features you would expect in a protocol analyzer, and several features not seen in any other product.

5. THC-Hydra - Number one of the biggest security holes are passwords, as every password security study shows. 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.

6. Metasploit Framework - The Metasploit Framework is an advanced open-source platform for developing, testing, and using exploit code. This project initially started off as a portable network game and has evolved into a powerful tool for penetration testing, exploit development, and vulnerability research.

7. John the Ripper - John the Ripper is a fast password cracker, currently available for many flavors of Unix (11 are officially supported, not counting different architectures), DOS, Win32, BeOS, and OpenVMS. Its primary purpose is to detect weak Unix passwords. Besides several crypt(3) password hash types most commonly found on various Unix flavors, supported out of the box are Kerberos AFS and Windows NT/2000/XP/2003 LM hashes, plus several more with contributed patches.

8. Nessus - Nessus is the world's most popular vulnerability scanner used in over 75,000 organisations world-wide. Many of the world's largest organisations are realising significant cost savings by using Nessus to audit business-critical enterprise devices and applications.

9. IRPAS - Internetwork Routing Protocol Attack Suite - Routing protocols are by definition protocols, which are used by routers to communicate with each other about ways to deliver routed protocols, such as IP. While many improvements have been done to the host security since the early days of the Internet, the core of this network still uses unauthenticated services for critical communication.

10. Rainbowcrack - RainbowCrack is a general propose implementation of Philippe Oechslin's faster time-memory trade-off technique. In short, the RainbowCrack tool is a hash cracker. A traditional brute force cracker try all possible plaintexts one by one in cracking time. It is time consuming to break complex password in this way. The idea of time-memory trade-off is to do all cracking time computation in advance and store the result in files so called "rainbow table". 

How to Install ubuntu Step- By-Step Guide

Installing Ubuntu

1. Get an Ubuntu installation disk (liveDVD or liveUSB).
2. Insert the Ubuntu disk into your DVD drive. (or connect your liveUSB)
3. Make sure that your BIOS (boot order) is set to boot from a CD/USB before a hard drive.
4. Start or restart your computer. If you do not see the Ubuntu logo, please refer to BootFromCD.
5. Choose the Try Ubuntu option in order to check that your hardware (screen, keyboard, internet...) is correctly recognized by Ubuntu.
6. Backup your documents on an external disk or DVDs
7. When you are ready to install Ubuntu on your hard disk, click the Install Ubuntu button. The installation wizard will appear:

Selecting language

• 

Select your desired language and click Continue. The Preparing to install Ubuntu window appears.

Preparing to install Ubuntu

• 

Select the desired options. Click Continue. The Installation type window appears.

Installation type

• 

Several choices are available:

- If you want to install Ubuntu alongside you other systems (eg alongside Windows), select the Install Ubuntu alongside them.

- If you want to install Ubuntu over your entire hard drive, select Erase disk and install Ubuntu, then select the hard drive that you want to install Ubuntu. Warning: this will erase all data and systems that are currently on the disk.

- If you want to manually setup your partitioning scheme, , select the Something else option. You will find further advice on the DiskSpace page.

Click Install now. From this point, the installation cannot be cancelled. Few additional parameters need to be setup. The Where are you? window appears.

Where are you?

• 

Select the location closest to your location. Click Continue. The Keyboard layout window appears.

Keyboard layout

• 

Select the correct keyboard layout. Click Continue. The Who are you? window appears.

Who are you?

• 
  When the installation wizard finishes, the Installation complete window appears.

Installation complete

• 
  Click Restart now to restart your computer. Ubuntu is now installed.