#!/bin/bash
# at start add
trap “” 2 20

# your script
echo ” Test”

# loop for sleep
sleep 5

trap -l command list all signals

20 is for CTRL + Z
2 is for CTRL  + C

Here is full list created by trap -l command:

1) SIGHUP     2) SIGINT     3) SIGQUIT     4) SIGILL
5) SIGTRAP     6) SIGABRT     7) SIGBUS     SIGFPE
9) SIGKILL    10) SIGUSR1    11) SIGSEGV    12) SIGUSR2
13) SIGPIPE    14) SIGALRM    15) SIGTERM    16) SIGSTKFLT
17) SIGCHLD    18) SIGCONT    19) SIGSTOP    20) SIGTSTP
21) SIGTTIN    22) SIGTTOU    23) SIGURG    24) SIGXCPU
25) SIGXFSZ    26) SIGVTALRM    27) SIGPROF    28) SIGWINCH
29) SIGIO    30) SIGPWR    31) SIGSYS    34) SIGRTMIN
35) SIGRTMIN+1    36) SIGRTMIN+2    37) SIGRTMIN+3    38) SIGRTMIN+4
39) SIGRTMIN+5    40) SIGRTMIN+6    41) SIGRTMIN+7    42) SIGRTMIN+8
43) SIGRTMIN+9    44) SIGRTMIN+10    45) SIGRTMIN+11    46) SIGRTMIN+12
47) SIGRTMIN+13    48) SIGRTMIN+14    49) SIGRTMIN+15    50) SIGRTMAX-14
51) SIGRTMAX-13    52) SIGRTMAX-12    53) SIGRTMAX-11    54) SIGRTMAX-10
55) SIGRTMAX-9    56) SIGRTMAX-8    57) SIGRTMAX-7    58) SIGRTMAX-6
59) SIGRTMAX-5    60) SIGRTMAX-4    61) SIGRTMAX-3    62) SIGRTMAX-2
63) SIGRTMAX-1    64) SIGRTMAX

Related posts:

1. Download youtube videos in ubuntu linux
2. Perl script for search & replace in several files
3. search & replace in several files in perl script

In its crudest form, this is called “poking a hole in the firewall.” I’ll call it an SSH back door. To use it, you’ll need a machine on the Internet that you can use as an intermediary.

In our example, we’ll call our machine blackbox.example.com. The machine behind the company firewall is called ginger. Finally, the machine that technical support is on will be called tech. Figure 4 explains how this is set up.

SSH Back Door

Here’s how to proceed:

1. Check that what you’re doing is allowed, but make sure you ask the right people. Most people will cringe that you’re opening the firewall, but what they don’t understand is that it is completely encrypted. Furthermore, someone would need to hack your outside machine before getting into your company. Instead, you may belong to the school of “ask-for-forgiveness-instead-of-permission.” Either way, use your judgment and don’t blame me if this doesn’t go your way.
2. SSH from ginger to blackbox.example.com with the -R flag. I’ll assume that you’re the root user on ginger and that tech will need the root user ID to help you with the system. With the -R flag, you’ll forward instructions of port 2222 on blackbox to port 22 on ginger. This is how you set up an SSH tunnel. Note that only SSH traffic can come into ginger: You’re not putting ginger out on the Internet naked.You can do this with the following syntax:

   ~# ssh -R 2222:localhost:22 thedude@blackbox.example.com

   Once you are into blackbox, you just need to stay logged in. I usually enter a command like:

   thedude@blackbox:~$ while [ 1 ]; do date; sleep 300; done

   to keep the machine busy. And minimize the window.

3. Now instruct your friends at tech to SSH as thedude into blackbox without using any special SSH flags. You’ll have to give them your password: root@tech:~# ssh thedude@blackbox.example.com .
4. Once tech is on the blackbox, they can SSH to ginger using the following command: thedude@blackbox:~$: ssh -p 2222 root@localhost
5. Tech will then be prompted for a password. They should enter the root password of ginger.
6. Now you and support from tech can work together and solve the problem. You may even want to use screen together! (See Trick 4.)

Related posts:

1. Checking your bandwidth
2. How to block websites in Ubuntu Linux
3. Hack Windows Admin Password using Ubuntu Linux

Here’s how you find the process that holds your DVD drive and eject it to your heart’s content: First, simulate it. Stick a disk in your DVD drive, open up a terminal, and mount the DVD drive:

# mount /media/cdrom
# cd /media/cdrom
# while [ 1 ]; do echo "All your drives are belong to us!"; sleep 30; done

Now open up a second terminal and try to eject the DVD drive:

# eject

You’ll get a message like:

umount: /media/cdrom: device is busy

Before you free it, let’s find out who is using it.

# fuser /media/cdrom

You see the process was running and, indeed, it is our fault we can not eject the disk.

Now, if you are root, you can exercise your godlike powers and kill processes:

# fuser -k /media/cdrom

Boom! Just like that, freedom. Now solemnly unmount the drive:

# eject

fuser is good.

Related posts:

1. How to repair windows using linux
2. How to open .chm files in ubuntu
3. Ubuntu fire eye wallpaper