1 and 0

What is the APN? How do you change it?

1ve0 — Thu, 31 May 2012 03:27:32 +0000

APN (Access Point Names) means a network or carrier that your cell phone or tablet accesses for data. It describes which wireless network you are using when you try to connect a telecom operator such as AT&T, Verizon, T-Mobile etc. It also defines your IP address type or security mechanism.

You may need to change your sim card’s APN for several reasons (Especially for testing purposes). The way to change APN depends on your device:

iPhone: Settings > General > Network > Cellular Data Network
iPad: Settings > Cellular Data > APN Settings
Android: Go to Settings > Wireless & Network > Mobile Networks > Access Point Names
PC: Use your carrier special application. For example, It is AirCard Watcher If you are using Sierra Wireless Data Card. You can change it when internet is disconnected. After changing it, you must unplug and plug it in again (It is called Power Cycle). Don’t forget to change “Connection type“. It must be “Autoconnect“.

Changing APN on Sierra Wireless Data Card

User is not in the sudoers file. This incident will be reported.

1ve0 — Fri, 27 Apr 2012 23:54:50 +0000

When you try to install a package on Linux, you may face an error like this:

user@linux-debian-gnu:/$ sudo /usr/sbin/visudo
We trust you have received the usual lecture from the local System Administrator. 
It usually boils down to these three things:
#1) Respect the privacy of others.
#2) Think before you type.
#3) With great power comes great responsibility.
[sudo] password for user:
User is not in the sudoers file. This incident will be reported.

You need to add your user to sudoers file. In order to do that; login as root and type the following:

echo 'user ALL=(ALL) ALL' >> /etc/sudoers

Note: You must use your own username instead of “user”.

Desktop enhancements on GNOME 3.2

1ve0 — Sun, 08 Apr 2012 00:33:39 +0000

You may fed up with your default desktop interface If you don’t add new features to GNOME. Especially If you are an experienced Windows user, you probably look for similar taskbar, icons and other useful tools.

I will mention about two small tools to enhanced your desktop experience on Linux:

Gnome Tweak Tool
Tint2

You may download these tools from “Add/Remove Software“.

Gnome Tweek Tool and Tint2 Installation

To use these tools after installation, look for “Advanced Settings” and “TintWizard” on “Activities > Applications” menu.

Configuration

Although all tweak tools, you may want to change your desktop environment from GNOME to KDE. Here is the code you should use for that (you will need root privileges):

yum install @kde-desktop
.

How do you enable root login on Linux?

1ve0 — Fri, 06 Apr 2012 03:50:55 +0000

The root user is not allowed to login on several linux distributions by default (Especially the ones have GNOME).

Enabling root login

To enable root login, apply these commands (It has been tried under Fedora 16. Probably It has similar procedure for other linux systems):

Open configuration file:
```
su -
gedit /etc/pam.d/gdm
```
Find that line and add “#” to beginning of the line. Then save it.
```
# auth required pam_succeed_if.so user != root quiet
```
Do the same thing for “/etc/pam.d/gdm-password” file.

Remote Desktop Connection to Linux (Fedora 16) from Windows 7

1ve0 — Wed, 04 Apr 2012 00:11:44 +0000

I’ll explain how to connect Fedora linux remotely from Windows. You have plenty of choices to do that. Two of them are here:

TightVNC Viewer
TeamViewer

First of all, you should allow other users to connect your linux desktop. On Fedora, follow this path: “Activities > Applications > Desktop Sharing“. Click to “Allow other users to view your desktop“.

Fedora Remote Connection Settings

You may also need to disable or set your Firewall on Fedora.

Method 1:

Download and install TightVNC Viewer. Type linux IP address and connect.

Remote Connection with TightVNC

Method 2:

Download and install TeamViewer. Start TeamViewer on Linux. Write your ID and password down. Open TeamViewer on Windows. Connect to linux using ID and password that you wrote down.

Remote Connection with TeamViewer

P.S. TeamViewer is faster than TightVNC.

Enjoy:

TeamViewer

Remote server connection by SSH using C#

1ve0 — Mon, 19 Mar 2012 04:10:04 +0000

SSH is a secure network protocol to use remote shell services or execute commands. You can connect to a remote server by SSH on Visual Studio. To do this, you need a SSH library. My suggestion is SharpSSH.

Download DLL files from SourceForge. You should add these DLL files to your Visual Studio project:

DiffieHellman.dll
Org.Mentalis.Security.dll
Tamir.SharpSSH.dll

To connect to server and execute commands, code is here:

SshExec shell = new SshExec(hostIP, username);
shell.Password = password;
shell.Connect();
string output = shell.RunCommand(command);
shell.Close();

My SSH application is below. It is a simple SSH Command Prompt.

SSH Command Prompt

Creating PDF, Word, Excel, Outlook and Text files using C#

1ve0 — Mon, 19 Mar 2012 02:37:33 +0000

When you develop an application that needs exporting capability for several type of files, you should use some internal or external programming libraries. I will mention a few useful and free libraries for our exporting purposes.

Data Export

I don’t want to give much explanation about these libraries because you can find out easily If you want. My purpose is giving the summary (library name and basic code) about that.

Creating PDF File

Library: iTextSharp

Document document = new Document();
PdfWriter writer = PdfWriter.GetInstance(document, new System.IO.FileStream
("C:\\test.pdf", System.IO.FileMode.Create));
document.Open();
document.Add(Paragraph p1 = new Paragraph("Hello World"););
document.Close();

Creating Word File

Library: Microsoft Word 14.0 Object Library (Internal)

Application app1 = new Application();
app1.Visible = true;
_Document doc1 = app1.Documents.Add();
doc1.Words.First.InsertBefore("Hello World");
doc1.SaveAs2("C:\\test.docx");

Creating Excel File

Library: Microsoft Excel 14.0 Object Library (Internal)

_Application app = new Application();
_Workbook workbook = app.Workbooks.Add(Type.Missing);
_Worksheet worksheet = null;
app.Visible = true;
worksheet = workbook.Sheets["Sheet1"];
worksheet = workbook.ActiveSheet;
worksheet.Cells[1, 1] = "Hello World";
worksheet.Columns.AutoFit();
worksheet.Cells.HorizontalAlignment = Element.ALIGN_RIGHT;
workbook.SaveAs("C:\\test.xls", Type.Missing, Type.Missing, Type.Missing,
Type.Missing, Type.Missing, XlSaveAsAccessMode.xlExclusive, Type.Missing,
Type.Missing, Type.Missing, Type.Missing);

Creating Outlook Files (New Mail Window)

Library: Microsoft Outlook 14.0 Object Library (Internal)

Outlook.Application oApp = new Outlook.Application();
Outlook.MailItem oMsg = (Outlook.MailItem)oApp.CreateItem
(Outlook.OlItemType.olMailItem);
oMsg.HTMLBody = "Hello World";
oMsg.Display();

Creating Text Files

Library: System.IO (Internal)

System.IO.File.WriteAllText("C:\test.txt", "Hello World");

Notes

To open a file, use this code:

System.Diagnostics.Process.Start("test.pdf");

Before using any library (dll), do not forget to add it as a reference (Visual Studio > Solution Explorer > Right Click on References > Add Reference):

Add Reference Window in Visual Studio

Resolution of “Cygwin installation is out of date” error when you install Moshell on Cygwin

1ve0 — Sat, 03 Mar 2012 01:56:12 +0000

After install Cygwin by following this document (or this one as backup), the next step would be installing Moshell (Step 13 in that document). When you type “bash moshell_install” command, you see an error like this:

!!! Your cygwin installation is out of date and incompatible with the latest moshell version !!!
Please upgrade to the latest cygwin version by rerunning the setup.exe from www.cygwin.com/setup.exe

Cygwin Version Error

It is a common problem. You are not alone. To resolve this problem:

Check your cygwin version (Command: “cygcheck -V“)
Cygwin Version Check
Check www.cygwin.com for the latest version.
If you are sure that you have latest version, open “moshell_install” file (under “C:\cygwin\home\USERID“).

Change rows 201 between 209 as the screenshot below (add “#” symbols before commands):

The resolution

Here you are:

Moshell Connection Successfull

What is iperf, jperf and xjperf? How can you use them to test network performance?

1ve0 — Thu, 16 Feb 2012 23:29:17 +0000

Iperf is a very helpful tool written in C++ to measure network bandwidth and quality. It can be used to analyze both TCP and UDP traffic.

Jperf or Xjperf (both of them are the same thing. Don’t confuse about the difference) equip Iperf with graphical interface. If you don’t like to spend your time by command line, use Jperf.

I am going to give you some information about Iperf and Jperf. First of all, the project links of these tools are here:

Iperf: http://sourceforge.net/projects/iperf/
Jperf: http://sourceforge.net/projects/jperf/

Quick Iperf Example:

Iperf is an “exe” file (I am talking about Windows of course. If you are wonder about Iperf on Linux, see last section of this article). Download this exe file by here or here. Open a command prompt (Start > Run > cmd). Go to folder which exe file is in.

We are beginning to study Iperf

It can be used as server or client. I mean the same exe file can be server or client.

To use Iperf as server, use:
```
iperf -s
```
To use Iperf as client, use:
```
iperf -c IPaddress
```

Iperf as server

Iperf as client

As you see above, average bandwidth is 13.0 Mbits/sec in this example. To find out that, Iperf has sent 15.5 MBytes in 10 seconds.

We are going deep in Iperf:

Indeed, Iperf is not easy as It seems. There are almost 30 commands for Iperf. To see all commands, use this command:

iperf --help

Iperf commands

In this case, we want to test our download and upload speed for TCP by specific windows size, interval and time.

Testing download speed:

Here is the environment:

Computer1 (main computer in the office that we want to test download/upload speed in)
Laptop2 (remote computer in another office)
Windows size: 384 KB
Interval: 1 second
Time: 20 seconds

The key point is client sends packets to server (Client generates network traffic). So:

If you want to see download speed for Computer1, you should configure it as Iperf server. Thus Computer2 sends packets to Computer1. Computer1 receives/downloads these packets.
If you want to see upload speed for Computer1, you should configure it as Iperf client. Thus Computer1 sends packets to Computer2. It means Computer1 uploads these packets.

Testing download speed for Computer1

Write these commands for the test:

On Computer 1:
```
iperf -s
```
On Computer 2:
```
iperf -c IPaddress -i 1 -t 20 -w384K
```

Do not forget to write your IP address instead of IPaddress!

After that, command lines are going to be like that:

After TCP download test for Computer 1. This screenshot is from Iperf client (Computer 2)

After TCP download test for Computer 1. This screenshot is from Iperf server (Computer 1)

As you see, totally 29.2 MB has been sent in 10 seconds. Average speed is 24.3 Mbits/sec.

Testing upload speed:

The environment is going to be the same with “testing download speed” section but iperf server and client computers should change.

Testing upload speed for Computer1

Write these commands for the test:

On Computer 1:
```
iperf -c IPaddress -i 1 -t 20 -w384K
```
On Computer 2:
```
iperf -s
```

Do not forget to write your IP address instead of IPaddress!

After that, command lines are going to be like that:

After TCP upload test for Computer 1. This screenshot is from Iperf server (Computer 2)

After TCP upload test for Computer 1. This screenshot is from Iperf client (Computer 1)

As you see, totally 12.6 MB has been sent in 10 seconds. Average speed is 10.4 Mbits/sec.

UDP Test:

You need to “-u” parameter for UDP test. You can see jitter (delay correlation) and data gram. Here is a quick example.

UDP test result of Iperf client

UDP test result of Iperf server

Iperf on Linux:

To install Iperf on Linux, use these commands:

wget http://78.40.227.80/~depo/iperf-2.0.5.tar.gz
tar xvfz iperf-2.0.5.tar.gz
cd iperf-2.0.5
./configure
make
&& make install

Commands are the same as commands on Iperf Windows version. Just be aware of default windows packet size (It is 85.3 KB).

Iperf on Linux

Jperf:

Jperf installation is as easy as regular program installation on Windows. Just you need to JDK or JRE first of all.

Download Jperf for Windows by here. Extract it.
Download JRE or JDK by here.
Click to “jperf.bat” in Jperf folder.

Jperf UI

Notes:

Use “-P” parameter for paralel test.
If you want to save Iperf output, add this command at the end of line: “> c:\output.txt”. For example:

iperf -c IPaddress -i 1 -t 20 -w384K > c:\output.txt

Enjoy!

If you have any question, send a comment guys. I am working hard with Iperf nowadays.

Which FTP client is better: FileZilla, CuteFTP or TotalCommander?

1ve0 — Thu, 16 Feb 2012 05:27:03 +0000

Most people think that FTP speed depends on server and network speed. How about FTP client? Which FTP client should you prefer If you need high speed?

Which one is the best?

I tested three FTP clients:

FileZilla 3.5.3
CuteFTP 8.3.2
Total Commander 7.55

Here is test environment:

Operating system: Windows 7 Ultimate
FTP Server speed: 30 Mbps (download), 140 Mbps (upload)
Network speed: 32 Mbps (download), 2 Mbps (upload)

I have tried download/upload three times and calculated average. All clients have had the same conditions. The results:

FTP clients comparison

* I used multi-part download and normal upload on CuteFTP. I used default settings on FileZilla and Total Commander.
* Passive mode was used for both download and upload (Find out more).

As a result:

Don’t use Total Commander! Upload speed of Total Commander is terrible!
If you like open source programs choose FileZilla.
If you like programs that have user-friendly interface, choose CuteFTP.

By the way, my favorite is CuteFTP!