Tech Tips for everyone

Configure iptables to bypass the ttl=1 set by ISP

2008-10-17T21:37:00.000-07:00

I've just got a cheap 24hours internet account where my ISP sets a ttl = 1 which prevents it from sharing with multiple computers at a time. Which cannot stop me from using the mighty iptables and live a peaceful life. Here is a quick tip as to set up an internet connection sharing and at the same time change the ttl values.

A fancy ascii connection structure

LanComputer (A, 192,168.1.100) ------> gateway(B, eth1 192.168.1.1)

gateway(B, ppp0 public ip) ------------> ISP (internet)

Here are the magic lines


$ sudo iptables -t nat -A POSTROUTING -j MASQUERADE
$ sudo iptables -A FORWARD -i ppp0 -o eth1 -s 192.168.1.0/24 -m state --state NEW -j ACCEPT
$ sudo iptables -A FORWARD -m state --state ESTABLISHED,RELATED -j ACCEPT
$ sudo iptables -t mangle -A PREROUTING -j TTL --ttl-inc 1

Also for internet connection sharing make sure the ip forwarding is setup. Here is the command.

$sudo sh -c "echo 1 > /proc/sys/net/ipv4/ip_forward"

More on internet connection sharing is available at https://help.ubuntu.com/community/Internet/ConnectionSharing

Now someone needs to test this with openwrt or ddwrt.

Cheers

My favorite Firefox Extentions

2008-09-05T23:52:00.000-07:00

Extentions that i cannot live without in firefox.

1) Adblock Plus
Blocks all the adds, just couldn't live without it.
https://addons.mozilla.org/en-US/firefox/addon/1865

2) delicious bookmarks
Synchronizes all my bookmarks with del.icio.us. There is offline storage of bookmark which opens in a sidebar. Its really helpful.
http://delicious.com/help/quicktour/firefox

3) Downthemall
Helpful for quick and easy download. Supports resume and multiple part download. I rarely use an external downloader now.
http://www.downthemall.net

4) Firebug
Extremely helpful for debugging websites. If you are a webdeveloper then this is a must install addon. Helps to debug http requests, inspect DOM, modify CSS on the fly and lots of other features.
http://www.getfirebug.net

5) Fast Dial
When you open a new tab or a new window, it shows you a the thumbnail display of the websites you add to it. Its like a shortcut to most frequently used website. Extremely helpful.
https://addons.mozilla.org/en-US/firefox/addon/5721

6) Wikia Search Extension
Google isn't the only search engine. Now wikia is in my view a good open source alternative with user feedback option. You can add submit websites by a single Submit button. Also there is feature of rating as well.
https://addons.mozilla.org/en-US/firefox/addon/8267

7) Zotero
Saves your notes and research links inside your browser. Also it has option to sync your notes online. Helpful when you are doing lots of researches.
https://addons.mozilla.org/en-US/firefox/addon/3504

8) Tabs open relative
When google chrome was released, i loved its feature of opening new tab right beside the old tab. No more scrolling to the end of the tab list. Saves a lot of time and ease of use.
https://addons.mozilla.org/en-US/firefox/addon/1956

9) Tab duplicate
Duplicates the current tab. Helpful sometimes although i dont use it too much.
https://addons.mozilla.org/en-US/firefox/addon/28

10) Switch Proxy
Save a list of proxies. It then can be used as a minimalistic interface to switch between proxies. Very easy to use.
https://addons.mozilla.org/en-US/firefox/addon/125

Lots more useful addons available at https://addons.mozilla.org

Cheers all

Disable touchpad temporarily in HardyHeron Kubuntu/Ubuntu

2008-07-21T06:50:00.000-07:00

This has been bugging me for a long time. Everytime i start typing a long paragraph, the cursor would randomly move to a different section of the paragraph messing up my typing.

Since the ksynaptics and gsynaptics have been removed from the HardyHeron repositories, i found these two really nice command line tools.

The syndaemon and the synclient programs

But first, before using those two command, we have to allow other programs to share the memory of the touchpad, this can be done by editing the /etc/X11/xorg.conf file. Look for a section called Synaptic Touchpad

Originally i had the section like this
Section "InputDevice"
Identifier "Synaptics Touchpad"
Driver "synaptics"
Option "SendCoreEvents" "true"
Option "Device" "/dev/psaux"
Option "Protocol" "auto-dev"
Option "HorizEdgeScroll" "0"
EndSection

I had to add an extra line Option "SHMConfig" "on" so that my new configuration now looks like

Section "InputDevice"
Identifier "Synaptics Touchpad"
Driver "synaptics"
Option "SendCoreEvents" "true"
Option "Device" "/dev/psaux"
Option "Protocol" "auto-dev"
Option "HorizEdgeScroll" "0"
Option "SHMConfig" "on"
EndSection

Now the syndaemon tool is really nice that it lest you modify the touchpad parameters.
Check out
$ syndaemon --help
for more info on it.

To automatically start syndaemon when KDE starts, i had to make a script and save it in ~/.kde/Autostart folder, so i did

$ vim ~/.kde/Autostart/syndaemon.sh
#!/bin/bash
/usr/bin/syndaemon -d -i 0.8 -t

and save the file.

the -d means run in background, -i 0.8 means disable the touchpad for 0.8seconds and the -t means Only disable tapping and scrolling, not mouse movements. Ofcourse more information can be viewed from man syndaemon or syndaemon --help

Logout and Login again, Happy typing.

Inkscape - Getting Alt+Click work on Linux

2008-06-10T06:27:00.000-07:00

In linux, Alt+Click is reserved by the window manager, atleast default KDE reserves it to move windows.

To disable it, go to Control Center > Desktop > Window Behavior > Window Actions
and change Modifier Key + Left Button = Nothing,

Problem should be solved.

Reference
http://wiki.inkscape.org/wiki/index.php/FAQ#How_to_make_Alt.2Bclick_and_Alt.2Bdrag_work_on_Linux.3F

Socks Tunneling, Muaaah....

2008-05-19T08:37:00.000-07:00

ssh has this very cool feature called dynamic port forwarding which acts as a SOCKS 5 proxy.

When I am in a bandwidth limited network (usually my university has not so good international connection, plus my home isp sucks), i connect to my server which is in NPIX through ssh and forward a local port in my machine to act as a socks proxy.

I then configure firefox to use the particular proxy and browsing becomes pleasent.

Until now I hadn't thought about using any other application other than firefox, I use downthemall to download files so that was sufficient.

Yesterday while updating my system, i needed to forward synaptic through the tunnel. Since synaptic only supports http proxy and not socks proxy, i was going nuts.

Thanks to tsocks, that problem has been solved.

Through tsocks, you can forward all the network activity of a program through a socks proxy, so just running synaptic or apt-get after tsocks means using the alternative bandwidth that we get :-) .

The whole system is as belows.

a) Connecting to a remote server and opening a socks proxy in local machine

bibek@godzilla:~$ ssh bibek@10.1.1.2 -D 1080
bibek@10.1.1.2's password:
Linux chichekServer 2.6.24-16-server #1 SMP Thu Apr 10 13:58:00 UTC 2008 i686

The programs included with the Ubuntu system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.

Ubuntu comes with ABSOLUTELY NO WARRANTY, to the extent permitted by
applicable law.

To access official Ubuntu documentation, please visit:
http://help.ubuntu.com/
Last login: Mon May 19 17:43:14 2008 from 10.1.1.1
bibek@chichekServer:~$

godzilla is my main server and chichekServer is my remote machine, through godzilla i logged into chichekServer and during that time, opened port 1080 in my local machine,

All i need now is to put the socks proxy name in firefox as below

Time to install tsocks in my home machine
bibek@godzilla:~$ sudo aptitude install tsocks

Configure tsocks to use localhost:1080 as proxy server
the last three lines of /etc/tsocks.conf are

server = 127.0.0.1
# Server type defaults to 4 so we need to specify it as 5 for this one
server_type = 5
# The port defaults to 1080 but I've stated it here for clarity
server_port = 1080

Now lets use tsocks to tunnel apt-get
bibek@godzilla:~$ tsocks apt-get install kde4

This should tunnel your application through the socks proxy. If you want to tunnel any other application just put tsocks in front of it.

This way we the benefit is we can tunnel even p2p applications through the socks proxy, which isn't possible through normal http proxies.

Cheers

Ubuntu ltsp-server-standalone

2008-03-31T11:04:00.000-07:00

I nearly pulled all my hairs, the thin client was successfully getting ip from dhcpd but wasn't loading the kernel

The problem was with tftpd, which wasn't starting as it was supposed to :(
i tried
sudo dpkg-reconfigure tftpd-hpa
but no luck

the problem was there was no entry in the /etc/inetd.conf file

so i added the line at the end
tftp dgram udp wait root /usr/sbin/in.tftpd /usr/sbin/in.tftpd -s /var/lib/tftpboot

and restart, client boots successfully :) Hurrah!!

Setup of a local LAN svn server

2008-03-26T23:33:00.000-07:00

In this article I will show you how to setup a local LAN svn server.

It assumes that you have all the tools already installed in your main server.

First lets create a new svn repository

$ svn create /home/user/SVNREPO
This creates our local SVNREPO folder, we will have to add projects on it

$ mkdir tmpdir
$ cd tmpdir
$ mkdir projectA
$ mkdir projectA/trunk
$ mkdir projectA/branches
$ mkdir projectA/tags
$ mkdir projectB
$ mkdir projectB/trunk
$ mkdir projectB/branches
$ mkdir projectB/tags
…
$ svn import . file:///home/user/SVNREPO --message 'Initial repository layout'
Adding         projectA
Adding         projectA/trunk
Adding         projectA/branches
Adding         projectA/tags
Adding         projectB
Adding         projectB/trunk
Adding         projectB/branches
Adding         projectB/tags
…
Committed revision 1.
$ cd ..
$ rm -rf tmpdir


There goes our project layout.

Now to access the svn through LAN, we'd use the svnserve command
Assuming our main server is 192.168.0.1, here is what we do

In server
$ svnserve -d -r /home/user/SVNREPO

And to authenticate our users so that to track of who changed what
we'll change the /home/user/SVNREPO/conf/svnserve.conf file

Uncomment these lines /home/user/SVNREPO/conf/svnserve.conf
[general]
anon-access = read
auth-access = write
password-db = passwd

And to add the authentication information in new file
/home/user/SVNREPO/conf/passwd

[users]
username=password
username2=password2

And we're done!!

To import a project
svn import . svn://192.168.0.1/projectA/trunk

Enter username and password as asked

To checkout an existing project
svn co svn://192.168.0.1/projectA/trunk projectALocal

Good day

KDE Look (Human 7.04 Color Scheme)

2008-02-12T18:14:00.000-08:00

I've finally found a look for KDE that looks pretty enough and standard upon whole Ubuntu Desktop.

I installed Polyster style
sudo aptitude install kde-style-polyester

and then put the Human Color Scheme
http://www.kde-look.org/content/show.php/Human+7.04?content=65116

and it now looks like this

Then, to get similar interface across whole GTK (GNOME) applications, I installed gtk-qt-engine and all gtk applications have a kde-ish look
sudo aptitude install gtk-qt-engine

Add it with nuvola Theme available at http://www.kde-look.org/content/show.php/nuvoX?content=38467 and I get a very satisfying desktop. <]:-)
Cheers All

Picasa on Linux and proxy setting

2008-01-24T08:31:00.000-08:00

Its been quite a while Google Released Versions for Linux, and few months back, they released 2.7 version beta for people to test on.
Im so impressed, now that Picasa on Linux finally supports web albums, easy one click upload. (Not really one click but still).

2.7 is fairly stable with minor issues but unnoticable.

Its been quite a while i've tried searching for a proxy setting in picas. Reading through the manual, found out Picasa uses the default Proxy setting in the Internet Explorer.

Since there isn't a easier way to setup proxy server through wine, google had a tutorial btw.

http://picasa.google.com/linux/faq.html#31 << FAQ for Picasa Linux
/opt/picasa/bin/wrapper regedit << picasa wine executable to open up register

The proxy settings are as in this page http://www.pctools.com/guides/registry/detail/292/

Cheers All

Download Manager For Linux

2007-12-19T07:45:00.000-08:00

I've tested a lot of download manager for linux,
aria, d4x, Multiget and the firefox downthemall,

my best experience is Orbit download manager+WINE, can be downloaded from here.

Works great. No worries!!!

Proftpd Anonymous Configuration

2007-12-13T04:55:00.000-08:00

Although i recently installed gproftpd which provides a graphical interface to manage proftpd, the following configuration is for the proftpd

First make a user which maps to the anonymous, (this is needed because the files being written/uploaded to the server needs an owner and we thus create the user and its alais anonymous.

sudo adduser ftpuser, or through Gnome/KDE's GUI interface.

This should create the skeleton directory and stuffs. We will share /home/ftpuser/ftpshared folder as a public folder, make sure its writable.

Put the following code at the bottom of proftpd.conf, in xampp it can be found in /opt/lampp/etc/proftpd.conf

<Anonymous /home/ftpuser/ftpshared>
User ftpuser
Group ftpuser
UserAlias anonymous ftpuser
AllowOverwrite off
AuthUsingAlias On
AnonRequirePassword Off
<Limit STOR CWD XCWD CDUP MKD READ WRITE DIRS>
AllowAll
</Limit>
<Limit DELE>
DenyAll
</Limit>
<Limit LOGIN>
AllowAll
</Limit>
DisplayLogin /home/ftpuser/ftpshared/welcome.msg
</Anonymous>

The allowed methods are written in caps within the Limit tag as attributes, the configuration i've done is greedy configuration, ie it allows to read and write but doesnot allow to delete any of the files or folders.

Also create a file /home/ftpuser/ftpshared/welcome.msg and put your welcome message inside it. We're done!!

Cheers!!

Mount a folder inside another folder (Binding)

2007-12-13T04:40:00.001-08:00

I'll show you how to mount a folder residing somewhere in a filesystem to another folder.

Its a line command,
sudo mount -o bind /sourcefolderurl /destinationfolderurl

Done! Now where is it useful?
I ran into this problem during my ftp server setup,
ftp://myserver mapped to file system /media/sda7/ftpshared, ie ftp://myserver/a.mp3 mapped to /media/sda7/ftpshared/a.mp3.

But i also had to share /opt/cache/apt/archives (all the .deb files) within the ftp server, creating symbolic links wasn't working since proftpd worked in a chrooted environment, thus this was a good solution.

sudo mount -o bind /opt/cache/apt/archives/ /media/sda7/ftpshared/archives

To automatically mount the folder, make an entry in /etc/fstab file at the very end,
/var/cache/apt/archives /media/sda7/ftpshared/archives auto bind,gid=46,defaults 0 0

And on every boot, the folder is automatically mounted.

Cheers!!

Edubuntu Setup Tips and Tricks

2007-12-09T02:29:00.000-08:00

Update: We new have a separate LTSP related blog for Nepali Deployments, check it out here

A)
The usplash was giving resolution problem.
It was fixed by changing the /etc/usplash.conf file and setting
cat /etc/usplash.conf
xres=640
yres=480

Nice!!

B)
Now originally the client were successfully logging in, but after sometime they stopped working, it was strange but after debugging and following links below, i found that edubuntu and sabayon (gnomes configuration editor, or sth...)

The discussion links have been posted here
exactly my problem
https://lists.ubuntu.com/archives/edubuntu-users/2007-June/001199.html

then it forwarded to sth ssh related, update ltsp ssh keys
https://lists.ubuntu.com/archives/edubuntu-users/2007-June/001202.html

in the last link, there was option to simply remove sabayon and well guess what? it worked perfectly!!!
sudo aptitude remove sabayon

I was glad that there wasn't much dependencies related with sabayon.

B.1)HowEVER!!
I reinstalled sabayon watching so many cool stuffs about it on the net. All i needed to do was to add the users/client to the profile and done!!

C)
The server was giving problems with bad gdm login screen, was fixed easily by reconfiguring the x-server
sudo dpkg-reconfigure -phigh xserver-xorg

D) Local USB Mount missing!!
Asked about it in #edubuntu in freenode.net and got this link
https://bugs.launchpad.net/ubuntu/+source/ltsp/+bug/160420
and scanning for the fix, got to this place,
http://article.gmane.org/gmane.linux.terminal-server.general/22270

The modifications i made as mentioned in the mailing list above are
a) comment out
env['DISPLAY'] = 'localhost:10.0' to # env['DISPLAY'] = 'localhost:10.0' in
/usr/sbin/ltspfsmounter

b) in file /opt/ltsp/i386/usr/share/ldm/rc.d/S10-delayed-mounter,
add a -X line to ssh connection string like this
ssh -X -S ${LDM_SOCKET} ${LDM_SERVER} "/usr/sbin/ltspfsmounter ${DIR} add"

c) finally update the ltsp image by executing
sudo ltsp-update-image

Recover Grub using Ubuntu Live CD

2007-12-07T06:02:00.000-08:00

If you have lost grub after install Windows and cannot boot Linux then this tip will help you restore grub and the boot Linux.

What we need?
Ubuntu Live CD

Steps
a) boot from Ubuntu Live CD
b) Open terminal
Applications > Accessories > Terminal

c) You will see the gnome terminal,Now we need to enter grub. In the terminal type
sudo grub

d) Now you will see a different prompt called grub>
Everycommand below will be typed in the grub> menu.
We need to find the root device, that contains the GRUB's first and second boot files
grub> find /boot/grub/stage1
(hd0,0)

Note that your output might be different depending upon the partition where u install linux, example say (hd0,6) or (hd1,5). When (hd0,0) is mentioned below, replace it with the output that u see here.

e) grub> root (hd0,0)

f) grub> setup (hd0)

g) now restart your computer and you should see your old grub screen, and your linux should work as well.

Cheers
Reference:
1) LINUX COOKBOOK by Carla Schroder

Alternative Ways to login to gmail

2007-11-26T02:36:00.000-08:00

Besides the normal way of logging in to gmail, there are alternative ways to sign in.

The ones i know of are html view and mobile view. Why this is necessary is during peak hours in college or when u are at home and just want to check ur email quickly, this is extremely useful.

To access the html version of gmail, use this link.

http://mail.google.com/mail/?ui=html

To access the mobile version of gmail, use this link.

http://m.gmail.com

They are extremely fast way to access gmail, but feature wize, its no match to gmail's ajax interface.

Do check them out.

Minimal Installation of Ubuntu

2007-11-20T06:59:00.000-08:00

I like ubuntu because the best part of it is the availability of applications on the main, universe and multiverse repos and the ease at which you can install them. Also applications just work!! in Ubuntu.

But since i own a P3 700mHz PC, a whole gnome desktop or kde desktop would cripple the system unable to run eclipse(my fav ide) and other dev stuffs.

For this i use Openbox+fbpanel, which makes a great combination.
I also install Ubuntu the commandline way, which gives me very much flexibility withouth the whole ubuntu default packages.

Here is how i do it usually

a) put the DVD version of the kubuntu and boot from it.
b) select install a command line system
c) go on with the installer until we have a good commandline system working.
d) now its time to pull up custom picked packages from the dvd. The following packages should be enough to have xserver working
1) sudo apt-cdrom add
This will add ur dvd to apt
2) sudo aptitude install kdm
3) sudo aptitude install ttf-indic language-pack-ne firefox xorg upsplash kwin konqueror kdecore kubuntu-default-settings kubuntu-artwork-usplash amarok pidgin kaffeine libxine1-ffmpeg sun-java krusader msttcorefonts gnome-icon-theme k3b kpdf gwenview openbox openbox-themes fbpanel kde-systemsettings kmix kate

Will take some time to install, i wonder if ur video card driver is installed, should be install, paitience

kdm should load fine and u can select openbox as ur default session.

initally u will only see a blank screen possibly with kubuntu wallpaper, right click and u will see openbox menu. No to integrate fbpanel into it, we will write 2 linex in openbox config

4) Right click and exit, load a session in kde and check ur home
bibek@monster:~$ cd ~/.config/openbox/

5) if there is a file called autostart.sh modify it else create it
bibek@monster:~$ kate ~/.config/openbox/autostart.sh
inside autostart.sh, i have these 2 lines

(sleep 2 && fbpanel) &
(sleep 2 && kmix) &

Save and exit
this will run fbpanel and kmix after ur openbox, logout of ur kde session and log in in openbox session, there should be fbpanel and kmix both.

To make ur work even easier, u can define openbox short cuts as i've defined them,
Inside /home/username/.config/openbox u should see a rc.xml file which has configurations for openbox. Open the file for editing and search for
Now before paste the following code. Read the code the understand what they will do, makes my day to day life much easier.


<keybind key="W-F12">
<action name="Execute">
<execute>firefox</execute>
</action>
</keybind>
<keybind key="W-F11">
<action name="Execute">
<execute>xterm</execute>
</action>
</keybind>
<keybind key="W-F10">
<action name="Execute">
<execute>pidgin</execute>
</action>
</keybind>
<keybind key="W-F9">
<action name="Execute">
<execute>/home/bibek/bin/eclipse/eclipse</execute>
</action>
</keybind>
<keybind key="W-F8">
<action name="Execute">
<execute>krusader</execute>
</action>
</keybind>
<keybind key="W-F7">
<action name="Execute">
<execute>amarok</execute>
</action>
</keybind>
<keybind key="W-F6">
<action name="Execute">
<execute>kaffeine</execute>
</action>
</keybind>

Cheers

HOWTO Install Counter Strike Source in Linux

2007-11-20T06:36:00.000-08:00

This post is to help you install counter strike (cracked one which we get in copied cds) in linux. It will also serve as a reference for me for later installations.

I have installed ubuntu gusty gibbon and the wine package that comes with it. do not install the new package from wine's dev repo coz that wasted my 2hrs of debugging time.

Steps
a) install wine in linux
bibek@monster:~$ sudo aptitude install wine

b) create urself a wine folder
bibek@monster:~$ winecfg

this will openup a configuration window. Close it up and everything should be alright

c) Install cs bu runnig the installer
bibek@monster:~$ cd cs
bibek@monster:~/cs$ wine setup.exe

After the installation is finished, we need to install gecko, which is required by cs to run

d) Run this in command line and it will download the gecko for wine,
bibek@monster:~/cs$ wine iexplore http://www.google.com

When u do this for the first time, it will download the gecko engine, after installations u should see google.com, next time u do this, i till directly load www.google.com
Gecko is used to load HTML components through wine, google on it 4 more info

e) We also need the mfc42.dll file from windows installation,
bibek@monster:~/cs$ cp /media/sda1/windows/system32/mfc42.dll /home/bibek/.wine/drive_c/windows/system32/

f) Finally we need the tahoma font, copy tahoma.ttf from windowsdrive\windows\fonts\tahoma.ttf to /home/usernamehere/.wine/drive_c/windows/fonts/tahoma.ttf
bibek@monster:~/cs$ cp /media/sda1/windows/Fonts/tahoma.ttf /home/bibek/.wine/drive_c/windows/fonts/

g) reboot wine
bibek@monster:~/cs$ wineboot

h) now we're ready to run cs
bibek@monster:~/cs$ cd ~/.wine/drive_c/Program\ Files/Valve/Counter\ Strike\ Source\ Final/
bibek@monster:~/.wine/drive_c/Program Files/Valve/Counter Strike Source Final$ wine hl2.exe -steam -console -game cstrike

And ur game should run without any problems.

NOTE
Running hl2.exe directly through wine will give error so make sure to pass the additional arguements as mentioned above in step g)
Following error is given
Unable to get IFileSystem interface from filesystem factory
Bugs please put in comments.