Posts Tagged ‘distro’

Linux: How to see / change supported network bandwidth of NIC interface and get various eth network statistics with ethtool

Monday, January 19th, 2015

linux-how-to-see-change-supported-network-bandwidth-of-NIC-interface-and-view-network-statistics
If you're a novice Linux sysadmin and inherited some dedicated servers without any documentation and hence on of the first things you have to do to start a new server documentation is to check the supported TCP/IP network speed of servers Network (ethernet) Interfaces. On Linux this is very easy task to verify the speed of LAN card supported Local / Internet traffic install ethtool (if not already preseont on the servers) – assuming you're dealing with Debian / Ubuntu Linux servers.

1. Install ethtool on Deb and RPM based distros

dedi-server1:~# apt-cache show ethtool|grep -i desc -A 3
Description: display or change Ethernet device settings
 ethtool can be used to query and change settings such as speed, auto-
 negotiation and checksum offload on many network devices, especially
 Ethernet devices.

dedi-server1:~# apt-get install –yes ethtool
..

ethtool should be installed by default on CentOS / Fedora / RHEL and  syntax is same like on Debs. If you happen to miss ethtool on any (SuSE) / RedHat / RPM based distro install it with yum

[root@centos:~] # yum -y install ethtool


2. Get ethernet configurations

To check the current eth0 / eth1 / ethX network (Speed / Duplex) and other network related configuration configuration:
 

dedi-server5:~# ethtool eth0

Settings for eth0:
        Supported ports: [ TP ]
        Supported link modes:   10baseT/Half 10baseT/Full
                                100baseT/Half 100baseT/Full
                                1000baseT/Full
        Supports auto-negotiation: Yes
        Advertised link modes:  10baseT/Half 10baseT/Full
                                100baseT/Half 100baseT/Full
                                1000baseT/Full

        Advertised pause frame use: No
        Advertised auto-negotiation: Yes
        Speed: 1000Mb/s
        Duplex: Full
        Port: Twisted Pair
        PHYAD: 1
        Transceiver: internal
        Auto-negotiation: on
        MDI-X: off
        Supports Wake-on: pumbag
        Wake-on: g
        Current message level: 0x00000001 (1)
        Link detected: yes

Having a NIC configured to act as Duplex is very important as Duplex communication enables LAN card to communicate both sides (Sent / Receive) packets simultaneously.

full-duplex-half-duplex-explained-picture

Probably most interesting parameters for most admins are the ones that are telling whether the NIC UpLink is 10megabyte / 100 megabyte or 1Gigabyte as well as supported Receive / Send ( Transfer ) speeds of LAN, a common useful ethtool admin use to just show current LAN ethernet interface speed:

server-admin1:~# ethtool eth0 |grep -i speed
        Speed: 1000Mb/s

 

To get info about NIC (kernel module / driver) used with ethtool:

dedi-server3:~# ethtool -i eth0 driver: e1000e
version: 1.2.20-k2
firmware-version: 1.8-0
bus-info: 0000:06:00.0

3. Make LAN Card blink to recognize eth is mapped to which Physical LAN

Besides that ethtool has many other useful use cases, for example if you have a server with 5 lan or more LAN cards, but you're not sure to which of all different EthX interfaces correspond, a very useful thing is to make eth0, eth1, eth2, eth3, etc. blink for 5 seconds in order to identify which static IP is binded physically to which NIC , here is how:

ethtool -p eth0 5


Then you can follow the procedure for any interface on the server and map them with a sticker 🙂

Ethtool is also useful for getting "deep" (thorough) statistics on Server LAN cards, this could be useful to identify sometimes hard to determine broadcast flood attacks:
 

4. Get network statistics with ethtool for interfaces
 

dedi-server5:~# ethtool -S eth0|grep -vw 0
NIC statistics:
     rx_packets: 6196644448
     tx_packets: 7197385158
     rx_bytes: 2038559235701
     tx_bytes: 8281206569250
     rx_broadcast: 357508947
     tx_broadcast: 172
     rx_multicast: 34731963
     tx_multicast: 20
     rx_errors: 115
     multicast: 34731963
     rx_length_errors: 115
     rx_no_buffer_count: 26391
     rx_missed_errors: 10059
     tx_timeout_count: 3
     tx_restart_queue: 2590
     rx_short_length_errors: 115
     tx_tcp_seg_good: 964136993
     rx_long_byte_count: 2038559235701
     rx_csum_offload_good: 5824813965
     rx_csum_offload_errors: 42186
     rx_smbus: 383640020

5. Turn on Auto Negotiation and change NIC set speed to 10 / 100 / 1000 Mb/s

Auto-negotiation is important as an ethernet procedure by which two communication devices (2 network cards) choose common transmission parameters such as speed, duplex mode, and flow control in order to achieve maximum transmission speed over the network. On 1000BASE-T basednetworks the standard is a mandatory. There is also backward compatability for older 10BASE-T Networks.

a) To raise up NIC to use 1000 Mb/s in case if the bandwidth was raised to 1Gb/s but NIC settings were not changed:

dedi-server1:~# ethtool -s eth0 speed 1000 duplex half autoneg off


b) In case if LAN speed has to be reduced for some weird reason to 10 / 100Mb/s

 

dedi-server1:~# ethtool -s eth0 speed 10 duplex half autoneg off

dedi-server1:~# ethtool -s eth0 speed 100 duplex half autoneg off

c) To enable disable NIC Autonegotiation:

dedi-server1:~# ethtool -s eth0 autoneg on


6. Change Speed / Duplex settings to load on boot

a) Set Network to Duplex on Fedora / CentOS etc.

Quickest way to do it is of course to use /etc/rc.local. If you want to do it following distribution logic on CentOS / RHEL Linux:

Add to /etc/sysconfig/network-scripts/ifcfg-eth0

vim /etc/sysconfig/network/-scripts/ifcfg-eth0

ETHTOOL_OPTS="speed 1000 duplex full autoneg off"

To load the new settings restart networking (be careful to have physical access to server if something goes wrong 🙂 )

service network restart

b) Change network speed / duplex setting on Debian / Ubuntu Linux

Add at the end of /etc/network/interfaces

vim /etc/network/interfaces

post-up ethtool -s eth0 speed 100 duplex full autoneg off

7. Tune NIC ring buffers

dedi-server1:~# ethtool -g eth0

Ring parameters for eth0:
Pre-set maximums:
RX:             4096
RX Mini:        0
RX Jumbo:       0
TX:             4096
Current hardware settings:
RX:             256
RX Mini:        0
RX Jumbo:       0
TX:             256

As you can see the default setting of RX (receive) buffer size is low 256 and on busy servers with high traffic loads, depending on the hardware NIC vendor this RX buffer size varies.
Through increasing the Rx/Tx ring buffer size , you can decrease the probability of discarding packets in the NIC during a scheduling delay.
A change in rx buffer ring requires NIC restart so (be careful not to loose connection to remote server), be sure to have iLO access to it.

Here is how to raise Rx ring buffer size 4 times from default value:

ethtool -G eth0 rx 4096 tx 4069

Raspberry Pi – Cheap portable credit-card sized single board Linux computer box

Thursday, November 7th, 2013

RaspberryPi tiny-computer running Linux and free software Logo

Not of a the latest thing out there but I believe a must know for every geek is existence of Raspberry Pi mini computer Linux board. It is a geek credit-card sized mini PC on extremely cheap price between 25$ and 35$ bucks (e.g. Raspberry Pi model A and Raspberry Pi Model B).

Raspberry Pi hardware you get for this ultra low price is as follows:

  • Broadcom BCM2835 system on chip
  • ARM Mobile processor model ARM1176JZF running at 700 Mhz (overlocking up to 1Ghz is possible – overclocked RP is called Turbo 🙂 )!
  • VideoCore IV GPU with 512 MBytes of ram
  • No Build hard disk or solid-state drive but instead designed to use SD-Card as a Storage
  • two video outputs
  • composite RCA and an HDMI port
  • 3.5mm audio output
  • 2 or 1SD/MMC/SDIO card slot (depending on device model A or model B)
  • Micro USB adapter power charger 500mA  (2.5 watts) – Model and 700mA (3.5 watts)

Raspberry PI mini computer hardware running Linux explained picture

The idea of whole device is to make cheap affordable device for pupils and people from third countries who can't afford to pay big money for a full-featured computer. Achievement is unique all you need to Raspberry Pi credit card sized device is external keyboard a mouse, SD-card and a monitor, this makes a 700Mhz featured almost fully functional computer for less than lets say 80$ whether used with a second hand monitor / mouse and kbd :). A fully functional computer or full functional thin client for as less as 80$ yes that's what RaspberryPi is!

It is recommendable that SD-Card storage on which it is installed is at least 4GB as this is part of its minimum requirement, however it is best if you can get an SD-Card of 32GBytes whether you plan to use its whole graphic functionalities.

Raspberry Pi Hardware is not too powerful to run a version of Windows as well as there is no free version of MS-Windows for ARM Processor, so basicly device is planned to run free software OSes GNU / Linux. 5 operating systems are working fine with the mini-board device as time of writting;
 

  • Raspbian – Debian "Wheezy" Linux port
  • Pidora – Fedora mixed version ported to run on Raspberry Pi
  • Risk OS port
  • Arch Linux port for ARM devices
  • Slackware Arm
    FreeBSD / NetBSD
  • QtonPi

Recommended and probably best distro port is for Debian Squeeze

To boot an OS into raspberry PI dowbnload respective image from raspberrypi.org

– Use application for copying and extracting image to SD-Card like Win32 Disk Imager – whether on Windows platform

Win32DiskImager burning raspberry PI mini Linux card board computer box image

– Or from Linux format SD-Card with gparted (N!B! format disk to be in FAT32 filesystem), extrat files and copy them to SD-CARD.

Once Raspberry Pi loads up it will drop you into Linux console, so further configuration will have to be done manually with invoking plenty of apt-get commands (which I will not talk about here as there are plenty of manuals already) – you will have to manually install your Desktop … Default shipped Web browser in Debian is Midori and due to lack of ported version of flash player for ARM streaming video websites like youtube.com / vimeo.com does not work in browser. There is a Google Chrome for Raspberry Pi port but just like with Midori heavy object loaded websites works very slow and thus not very suitable for multimedia.

raspberry pi cheaest portable linux powered computer sized of a credit card

Raspberry Pi device is very suitable for ThinClient use there is a special separate project – Raspberry ThinClient Project – using which a hobbyist can save 400$ for buying proprietary ThinClient.

RaspberryPI linux as a free software hardware thinclient picture

 

New FreeBSD version is out – Hello FreeBSD 9.2

Tuesday, October 1st, 2013

new version of FreeBSD is out FreeBSD 9.2

FreeBSD 9.2 is out today. There are mostly improvements in FreeBSD's ZFS. As usual BSD packages are updated with new ones. This version of BSD does not include anything revolutionary. Below are all the major changes in the distro. A list of all new introduced supports in that release as usual is in BSD's release notes

To all BSD users – Happy new BSD release 🙂

Create ASCII Art Text banners in GNU / Linux console and terminal with figlet and toilet

Tuesday, January 15th, 2013

Create fun and colorful text ASCII art banner logos on Linux (figlet and toilet)

As an old school hobbyist, I'm a kind of ASCII art freak. Free Software is just great for this text / console maniacs like me, who spend their youth years in a DOS (Disk Opearting System) command prompt.
For long time, I'm researching the cool programs which has to do somehow with ASCII Art, in that relation I decided to write few ones of figlet and toilettwo nice programs capable of generating ASCII art text beautiful banners based on a typed in text string. Obviously toilet developer Sam Hocevar had a great sense of humor 🙂

To play with figlet and toilet install them, according to (rpm or deb based package manager on distro) with yum / apt-get.

yum -y install toilet figlet
....

apt-get --yes install toilet figlet
....

There are no native tool packages for Slackware, so Slackaware Linux users need to compile figlet from source code – available on figlet's home page figlet.org

Once figlet and toilet are installed, here is few sample use cases;
 

hipo@noah:~/Desktop$ figlet hello world!             

figlet ascii art banner hello world
 

hipo@noah:~/Desktop$ figlet -f script Merrcy Christmas

figlet merry christmas text in ascii art with script font linux

Plenty of figlet font examples are available on Figlet's website example section – very cool stuff btw 🙂 To take a quick look on all fonts available for toilet – ascii art banner creation. Type in your console tty or terminal; for i in $(dpkg -L toilet-fonts|grep -i /usr/share/figlet); do toilet -f $(echo $i|sed -e "s#.tlf##g" -e "s#/usr/share/figlet/##g") test; done

On below picture, I made a screenshot of my gnome terminal with most fonts installed by toilet-fonts (fonts package).

ascii art banner create generate program linux figlet toilet with fonts on debian linux screenshot pic - how to create ascii banners linux

There are about 150 fonts, most of which needs to be downloaded and installed manually. A quick search online led me to a fonts collection of 263 figlet ascii art fonts – you can download a mirror of the file figletfonts40.zip here. To aid up toilet and  with those 263 extra fonts (on Debian) do; wget http://www.pc-freak.net/files/figletfonts40.zip cd /usr/share/figlets unzip figletfonts40.zip Note: you have to have installed unzip in advance, unzip is not in default install, so if you don't have it fetch it with; apt-get install --yes unzip toilet and figlet are partially compatible, between each other so most fonts should work okay on both.

figlet supports, also simple formatting of ASCII art banner, here is few examples with formatting; a.) format to center  

$ figlet -c bla bla

figlet centered ascii art text bla bla screenshot

b.) format to left


figlet ascii art banner left formatted text debian gnu linux

c. right formatting


figlet ascii art banner right formatted ascii art text debian linux generator

d. format to terminal width By default text that figlet generates is to suit for 80 rows terminals, normally on higher resolution in gnome-terminal and other Linux environments, terminals are not dimensioned 80×25, thus it is useful for longer sentences text to display text in accordance to terminal size;

figlet ascii art banner sentence phrase to terminal width banner debian gnu linux

The cool thing and advantage of toilet over figlet is toilet can print out ASCII art banners in colors – very very cool stuff; To quickly test all filters issue; for i in $(toilet -F list|awk '{ print $1 }'|grep -v Available|sed -e 's#"##g'); do toilet -F $i pC-fREAK; done Change text pC-fREAK with whatever you like;

> using toilet to create funny ascii-art banners linux pc-freak logo pictures

Very nice use of toilet or figlet, can be if it is placed to produce some nice message in ASCII banner on each user login. Other nice fun applications  is together with cowsay.

apt-cache show cowsay|grep -i description -A 5 Description: A configurable talking cow Cowsay (or cowthink) will turn text into happy ASCII cows, with speech (or thought) balloons. If you don't like cows, ASCII art is available to replace it with some other creatures (Tux, the BSD daemon, dragons, and a plethora of animals, from a turkey to an elephant in a snake).

In case interested in using cowsay on system logins, I suggest you check out my tiny cowrand script which uses cowsay and shows random cow ASCII art picture on each user login.

Also a good use if you're Christian is to combine, some nice Holy Scriptures  verse in text ascii with  some encouraging daily bible phrase from verse or fortune.

Apart from fun, common use of ASCII art slogans is in e-mail or blog comments ASCII art signatures, also they are certainly good for creating unusual (text) advertisements and even can be used to save printer ink:) cause text generated in ASCII art logo is not massive like most text fonts are 🙂 Last but not least  ASCII art banners are useful in generation of ASCII slogans as an art; after all ASCII art is one of innovative arts of 21st century 🙂

Xubuntu improve default picture viewing with gpicview

Tuesday, March 13th, 2012

The default picture viewer on Xubuntu's XFCE is risterroro. Risterroro is quite lightweight, but anyways is lacking even basic functionality with reading a number of pictures in a directory and showing, them one by one lacks any picture automated slider. The lack of picture back/forward functionality makes picture viewing very inconvenient on those Linux distro.

Ristretto Screenshot on Xubuntu Linux Desktop

Thanksfully this kind of unconfortable default behaviour on Xubuntu can easily be changed to use a handy picture viewer program called gpicviewxubuntu-linux:~# apt-get install --yes gpicview

gpicviewer grandmothers screenshot on Xubuntu Linux

Gpicview is a good minimalistic program which has all the functionality of the default GNOME picture viewer program eog – (eye of the Gnome). If you're aaccustomed to GNOME's eog you can always install and use eog instead 🙂

How to fix upside-down / inverted web camera laptop Asus K51AC issue on Ubuntu Linux and Debian GNU / Linux

Monday, February 13th, 2012

Skype Video Inverted bat like linux screenshot

Does your camera show video correctly in cheese but shows captured video upside-down (inverted) in skype ?
This is an issue a friend of mine experienced on his Asus K51AC-SX037D laptop on both Ubuntu and Debian Linux.
As you can see in the picture above it is funny as with this bug the person looks like a batman 😉
As the webcam upside-down issue was present on both latest Ubuntu 11.10 and latest stable Debian Squeeze 6.02, my guess was other GNU / Linux rpm based distro like Fedora might have applied a fix to this weird Skype inverted video (bat human like) issue.
Unfortunately testing the webcam with Skype on latest both Fedora 16 and Linux Mint 12 appeared to produce the same webcam bug.

A bit of research for the issue online and try outs of a number of suggested methods to resolve the issue led finally to a work around, thanks to this post
Here is few steps to follow to make the webcam show video like it should:

1. Install libv4l-0 package

root@linux:~# apt-get --yes install libv4-0
...

Onwards to start skype directly from terminal and test the camera type:

hipo@linux:~$ LD_PRELOAD=/usr/lib/libv4l/v4l1compat.so skype

This is the work around for 32 bit Linux install, most people however will probably have installed 64 bit Linux, for 64bit Linux installs the above command should be little different:

hipo@linux:~$ LD_PRELOAD=/usr/lib32/libv4l/v4l1compat.so skype

Once skype is launched test the camera and see if the camera capture is now uninverted, through menus:

S -> Options -> Video Devices -> Test

Skype Options Video devices screenshot

2. Create a skype Wrapper script Launcher

To make skype launch everytime with exported shell variable:
LD_PRELOAD=/usr/lib32/libv4l/v4l1compat.so

A new skype wrapper bash shell script should be created in /usr/local/bin/skype , the file should contain:

#!/bin/sh
LD_PRELOAD=/usr/lib32/libv4l/v4l1compat.so
/usr/bin/skype

To create the script with echo in a root terminal issue;

root@linux:~# echo '#!/bin/sh' >> /usr/local/bin/skype
root@linux:~# echo 'LD_PRELOAD=/usr/lib32/libv4l/v4l1compat.so' >> /usr/local/bin/skype
root@linux:~# echo '/usr/bin/skype' >> /usr/local/bin/skype
root@linux:~# chmod +x /usr/local/bin/skype

3. Edit the Skype gnome menu to substitute /usr/bin/skype Skype Launcher with /usr/local/bin/skype

Gnome 2 has a handy menu launcher, allowing to edit and add new menus and submenus (menus and items) to the Application menu, to launch the editor one has to click over Applications with last mouse button (right button) and choose Edit Menus

GNOME Edit menus screenshot

The menu editor like the one in the below screenshot will appear:

GNOME 2 Menu Editor Screenshot

In the preceeding Launcher properties window, Command: skype has to be substituted with:

GNOME2 Skype screenshot Launcher properties

Command: /usr/local/bin/skype

For console freaks who doesn't want to bother in editting Skype Launcher via GUI /usr/share/applications/skype.desktop file can be editted in terminal. Inside skype.desktop substitute:

Exec=skype

with

Exec=/usr/local/bin/skype

Skype fixed inverted bat like screenshot

As one can imagine the upside-down video image in Skype is not a problem because of Linux, but rather another bug in Skype (non-free) software program.
By the way everyone, who is using his computer with Free Software operating system FreeBSD, Linux etc. knows pretty well by experience, that Skype is a very problematic software; It is often a cause for system unexpected increased system loads, problems with (microphone not capturing), camera issues, issues with pulseaudio, problem with audio playbacks … Besides the long list of bugs there are unexpected display bugs in skype tray icon, bugs in skype messanger windows and at some rare occasions the program completely hangs and had to be killed with kill command and re-launched again.

Another worrying fact is Skype's versions available for GNU / Linux and BSD is completely out of date with its "competitor" operating systems MS Windows, MacOS X etc.
For people like me and my friend who want to use free operating system the latest available skype version is not even stable … current version fod download from skype's website is (Skype 2.2Beta)!

On FreeBSD the skype situation is even worser, freebsd have only option to run Skype ver 1.3 or v. 2.0 at best, as far as I know skype 2.2 and 2.2beta is not there.

Just as matter of comparison the latest Skype version on Windows is 5.x. Windows release is ages ahead its Linux and BSD ver. From a functional point of view the difference between Linux's 2.x and Windows 5.x is not that much different, what makes difference is is the amount of bugs which Linux and BSD skype versions contain…
Skype was about 6 months ago bought by Microsoft, therefore the prognosis for Skype Linux support in future is probably even darker. Microsoft will not probably bother to release new version of Skype for their competitor free as in freedom OSes.

I would like to thank my friend and brother in Christ Stelian for supplying me with the Skype screenshots, as well as for being kind to share how he fixed his camera with me.

Installing Linux on old hardware PC. Few thoughs on Puppy and Xubuntu Linux

Tuesday, January 24th, 2012

I needed a G/Linux distribution that will work fine on an old PC with hardware configuration:

guest@xubuntu-desktop:~$ grep -i cpu /proc/cpuinfo; free -m; df -h
cpu family : 6
cpu MHz : 797.613cpuid level : 2
total used free shared buffers cachedMem: 497 470 26 0 35 259-/+ buffers/cache: 176 321Swap: 1454 10 1444File System Size Used Free % Mounted on
/dev/sda1 37G 4,3G 31G 13% /

I've read a lot on the internet and come to the conclusion I have basicly two popular Linux distros as option to install on archaic x86 hardware:

1. Puppy Linux
2. Xubuntu Linux

I first give Puppy Linux a try. It worked quite nice, but the interface was too old school and the desktop felt like a bit out-dated.
Besides that many of the Puppy Linux shipped programs were not a mainstream programs available across most of the other Linux distributions.

Many of the programs shipped with Puppy are great, but more suitable for a computer geek than for a Windows accustomed GUI user.
Puppy Linux Screenshot

My opinion on Puppy (from what I've seen) is that its great distro for old school hardcore Linux users.
Anyways its not suitable for absolutely "uniniated" users who encounter Linux for a first time.

Secondly I installed Xubuntu. Most of the archaic hardware on the PC was detected during install time (a pleasently surprise).
Xubunto works fast and Xfce menus opens "light fast" as on the old 800Mhz pc with 512 mem of ram. Generally the GUI worked quick and responsive.
To conclude I liked Xubuntu a lot and I strongly recommend it to anyone who want to quickly roll on Linux on an old PC.
Xubuntu GNU / Linux theme

What impressed me most is the minimalistic look & feel and simplicity.

I'm sure Debian will be working great on old hardware as well, however configuring it will be hell a lot of work. Thus I think Xubuntu is a good choice for people who want save some time in obscure configurations and easily have a neat Linux ready for desktop use.

How to disable IPv6 on Debian / Ubuntu / CentOS and RHEL Linux

Friday, December 9th, 2011

I have few servers, which have automatically enabled IPv6 protocols (IPv6 gets automatically enabled on Debian), as well as on most latest Linux distribituions nowdays.

Disabling IPv6 network protocol on Linux if not used has 2 reasons:

1. Security (It’s well known security practice to disable anything not used on a server)
Besides that IPv6 has been known for few criticil security vulnerabilities, which has historically affected the Linux kernel.
2. Performance (Sometimes disabling IPv6 could have positive impact on IPv4 especially on heavy traffic network servers).
I’ve red people claiming disabling IPv6 improves the DNS performance, however since this is not rumors and did not check it personally I cannot positively confirm this.

Disabling IPv6 on all GNU / Linuces can be achieved by changing the kernel sysctl settings net.ipv6.conf.all.disable_ipv6 by default net.ipv6.conf.all.disable_ipv6 equals 1 which means IPv6 is enabled, hence to disable IPv6 I issued:

server:~# sysctl net.ipv6.conf.all.disable_ipv6=0

To set it permanently on system boot I put the setting also in /etc/sysctl.conf :

server:~# echo 'net.ipv6.conf.all.disable = 1 >> /etc/sysctl.conf

The aforedescribed methods should be working on most Linux kernels version > 2.6.27 in that number it should work 100% on recent versions of Fedora, CentOS, Debian and Ubuntu.

To disable IPv6 protocol on Debian Lenny its necessery to blackist the ipv6 module in /etc/modprobe.d/blacklist by issuing:

echo 'blacklist ipv6' >> /etc/modprobe.d/blacklist

On Fedora / CentOS there is a another universal “Redhat” way disable IPv6.

On them disabling IPv6 is done by editting /etc/sysconfig/network and adding:

NETWORKING_IPV6=no
IPV6INIT=no

I would be happy to hear how people achieved disabling the IPv6, since on earlier and (various by distro) Linuxes the way to disable the IPv6 is probably different.
 

Alto to stop Iptables IPV6 on CentOS / Fedora and RHEL issue:

# service ip6tables stop

# service ip6tables off

GUI wep/wpa cracking through Gerix Wifi Cracker NG (GUI for cracking wireless networks)

Thursday, December 10th, 2009

gerix-wifi-cracker-hack-into-wireless

I found a neat program that facilitates work on cracking
a wep or wpa secured wireless network. The program is called
Gerix Wifi Cracker NG and is a part of the
backtrack penetration testinglinux distro
Gerix Wifi Cracker itself is located here , it's cool cause the author even has prepared a deb
package with the nifty GUI wireless cracker
. The slogan of the soft is also a killer,it reads:
"The software that even your grandmother knows how to use!",
a bunch of nice granda's pictures are included as well 🙂