PHP exec system calls not working in Debian 6

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After migrating Current website to Debian 6, PHP calls exec and system stopped working.
The reason for it is debian package dash which modifies behaviour of system default shell:


# ls -l /bin/sh
lrwxrwxrwx 1 root root 4 Dec 9 20:25 /bin/sh -> dash

To revert this this behaviour to standard, execute


# dpkg-reconfigure dash

dash dpkg-reconfigure debian linux

Select “No” and default shell will be changed to standard bash.

You can check it with following command:


# ls -l /bin/sh
lrwxrwxrwx 1 root root 4 Dec 9 20:26 /bin/sh -> bash

Tags: , Posted by BackTrack in Linux on December 9, 2013

BackTrack Remove disks or other media

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After creating a bootable USB image for BackTrack 5 R3 with Unetbootin you may encounter an error:


Remove disks or other media
Press any key to restart

This means you have incorrect image on USB drive.

Simple solution is to use a different ISO to USB utility:

You can download it from following URL:

Universal USB Installer – Bootable Pendrive Software

Tags: Posted by BackTrack in Linux, Networking on November 25, 2013

Ansible No Package matching found available installed or updated

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When trying to manage packages with yum module via Ansible, on fresh installed RHEL / Centos Linux systems, you may face following error:


msg: No Package matching 'sendmail-cf' found available, installed or updated

This is caused by missing package yum-utils.

It can be installed with Ansible raw module (also used for installing python-simplejson for Ansible):


ansible 1.2.3.4 -m raw -a "yum -y install yum-utils" --user=userx --sudo

Tags: Posted by BackTrack in Linux on November 25, 2013

Cisco 800W WiFi configuration example

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Cisco 800-series devices have embedded AP in them.

Here is an example of simple configuration of wireless network on these routers (851W, 871W еtс).

In this example Network SSID: WiFi-SSID
Encryption is WPA-TKIP
WPA key: wpakey01
Network: 10.23.45.0/24

dot11 ssid WiFi-SSID
vlan 1
authentication open
authentication key-management wpa
guest-mode
wpa-psk ascii 0 wpakey01

bridge irb

interface Dot11Radio0
no ip address
!
encryption vlan 1 mode ciphers tkip
!
ssid WiFi-SSID

interface Dot11Radio0.1
encapsulation dot1Q 1 native
no cdp enable
bridge-group 1

interface BVI1
ip address 10.23.45.1 255.255.255.0
ip nat inside
ip virtual-reassembly

bridge 1 protocol ieee
bridge 1 route ip

You will probably want to have DHCP for wireless clients as well:

ip dhcp pool WiFi
network 10.23.45.0 255.255.255.0
default-router 10.23.45.1
dns-server 8.8.8.8 8.8.4.4

Don’t forget to add new wireless network to your NAT rule, in order to reach out the Internet.

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Dell PowerConnect switch firmware update

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Step 1.
Download firmware archive from dell website: ftp://ftp.dell.com/Pages/Drivers/powerconnect-5548-all.html

Step 2 – Extract .ros and .rfb files and place them on TFTP server.
Copy .ros image to system partition and .rfb image to boot partition.


SW01# copy tftp:///powerconnect_55xx-4108.ros system
SW01# copy tftp:///powerconnect_55xx_boot-10014.rfb boot

Step 3 – Check the current boot image.

GEKZNS02# show bootvar

Unit Image Filename Version Date Status
—- —– ——— ——— ——————— ———–
1 1 image-1 4.0.1.11 16-Oct-2011 18:10:50 Active*
1 2 image-2 4.1.0.8 28-Aug-2012 11:17:36 Not active

“*” designates that the image was selected for the next boot

Step 4 – Change the active image to new firmware.

GEKZNS02# boot system image-2

Step 5 – Verify the change.

GEKZNS02# show bootvar

Unit Image Filename Version Date Status
—- —– ——— ——— ——————— ———–
1 1 image-1 4.0.1.11 16-Oct-2011 18:10:50 Active
1 2 image-2 4.1.0.8 28-Aug-2012 11:17:36 Not active*

“*” designates that the image was selected for the next boot

Step 6 – Reboot the switch

GEKZNS02# reload

This command will reset the whole system and disconnect your current session. Do
you want to continue ? (Y/N)[N] Y
Shutting down …
Shutting down …
Shutting down …

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