Practical Code Solutions

Friday, June 15, 2012

How to create dynagen network topology with multible dynamips service

I explained "Using dynagen & dynamips for multible cisco router simulation" in the http://stdioe.blogspot.com/2012/06/using-dynagen-dynamips-for-multible.html article before. I'm going to talk about how to create a dynagen configuration for multiple dynamips service. Also we are going to work about dynagen performance optimization. Let's create a network topology to try on our system.

Now, we have got three dynamips services. Each single dynamips service is creating three virtual routers and all of them are connected to each other. The first dynamips service contains R1, R2 and R3 routers, the second dynamips service contains R4, R5 and R6 routers, the third dynamips service contains R7, R8 and R9 routers. They are seperated on configuration but logically they are connected to each other directly.

Start to practice,

1-) Starting dynamips services with different port numbers,

ismail@ismail-ThinkPad-T410:~$ dynamips -H 7200 &
ismail@ismail-ThinkPad-T410:~$ dynamips -H 7301 &
ismail@ismail-ThinkPad-T410:~$ dynamips -H 7402 &

2-) Create dynamips configuration file corresponding our network topology,

###############################1-Dynamips-1#############################
[localhost:7200]
  udp=10000
  workingdir = /tmp/workingdy1

[[3725]]
  image = /tmp/c3725-adventerprisek9-mz.124-15.T13.bin
  ram = 128
  #idlepc =  ?? # We will talk about this, later.
  ghostios = true
  sparsemem = true
  idlemax = 100 
  disk0=128

 [[Router R1]]
  model = 3725
  console = 2001
  autostart = false
  S0/0 = R2 S0/0

 [[Router R2]]
  model = 3725
  console = 2002
  autostart = false
  S0/0 = R1 S0/0
  S0/1 = R3 S0/0

 [[Router R3]]
  model = 3725
  console = 2003
  autostart = false
  WIC0/0 = WIC-2T
  S0/0 = R2 S0/1 
  S0/1 = R7 S0/1

###############################1-Dynamips-1#############################

###############################2-Dynamips-2#############################
[localhost:7201]
  udp=11000
  workingdir = /tmp/workingdy2

[[3725]]
  image = /tmp/c3725-adventerprisek9-mz.124-15.T13.bin
  ram = 128
  #idlepc =  ?? # We will talk about this, later.
  ghostios = true
  sparsemem = true
  idlemax = 100 
  disk0=128

 [[Router R4]]
  model = 3725
  console = 2004
  autostart = false
  S0/0 = R5 S0/0
  S0/1 = R8 S0/1

 [[Router R5]]
  model = 3725
  console = 2005
  autostart = false
  S0/0 = R4 S0/0
  S0/1 = R6 S0/0

 [[Router R6]]
  model = 3725
  console = 2006
  autostart = false
  S0/0 = R5 0/1

###############################2-Dynamips-2#############################

###############################3-Dynamips-3#############################
[localhost:7202]
  udp=12000
  workingdir = /tmp/workingdy3

[[3725]]
  image = /tmp/c3725-adventerprisek9-mz.124-15.T13.bin
  ram = 128
  #idlepc =  ?? # We will talk about this, later.
  ghostios = true
  sparsemem = true
  idlemax = 100 
  disk0=128

 [[Router R7]]
  model = 3725
  console = 2007
  autostart = false
  S0/0 = R9 S0/0
  S0/1 = R3 S0/1

 [[Router R8]]
  model = 3725
  console = 2008
  autostart = false
  WIC0/0 = WIC-2T
  S0/0 = R9 S0/1
  S0/1 = R4 S0/1

 [[Router R9]]
  model = 3725
  console = 2009
  autostart = false
  S0/0 = R7 0/0
  S0/1 = R8 0/0

###############################3-Dynamips-3#############################

I saved the content above with a file name of sample2.net name in /tmp directory. We need working directories as below:

ismail@ismail-ThinkPad-T410:~$ mkdir /tmp/workingdy1
ismail@ismail-ThinkPad-T410:~$ mkdir /tmp/workingdy2
ismail@ismail-ThinkPad-T410:~$ mkdir /tmp/workingdy3

3-) The working directories are ready. Right now, dynagen service is ready to start. I did a mistake to shown follow up how to troubleshooting.

ismail@ismail-ThinkPad-T410:~$ dynagen /tmp/sample2.net 
Reading configuration file...

Shutdown in progress...
Shutdown completed.
Shutdown in progress...
Shutdown completed.
Shutdown in progress...
Shutdown completed.
*** Warning:  Connecting R6 S0/0 to R5 0/1 resulted in:
 malformed destination interface: R5 0/1
*** Warning:  Connecting R9 S0/0 to R7 0/0 resulted in:
 malformed destination interface: R7 0/0
*** Warning:  Connecting R9 S0/1 to R8 0/0 resulted in:
 malformed destination interface: R8 0/0

*** Error:  errors during loading of the topology file, please correct them
Shutdown in progress...
Error: could not communicate with dynamips server localhost
It may have crashed. Check the dynamips server output.
Exiting...
Press ENTER to exit
[3]+  Segmentation fault      (core dumped) dynamips -H 7202
ismail@ismail-ThinkPad-T410:~$

Normally, you can define a connection on both ends of lines. But on our sample, dynagen service doesn't accept this duplicate defination. I removed " S0/1 = R6 S0/0" line in R5 router part. Also " S0/0 = R9 S0/0" line in R7 part and " S0/0 = R9 S0/1" line in R8 part. After editing, sample2.net file has a content as seen below:

###############################1-Dynamips-1#############################
[localhost:7200]
  udp=10000
  workingdir = /tmp/workingdy1

[[3725]]
  image = /tmp/c3725-adventerprisek9-mz.124-15.T13.bin
  ram = 128
  #idlepc =  ?? # We will talk about this, later.
  ghostios = true
  sparsemem = true
  idlemax = 100
  disk0=128

 [[Router R1]]
  model = 3725
  console = 2001
  autostart = false
  S0/0 = R2 S0/0

 [[Router R2]]
  model = 3725
  console = 2002
  autostart = false
  #S0/0 = R1 S0/0
  S0/1 = R3 S0/0

 [[Router R3]]
  model = 3725
  console = 2003
  autostart = false
  #S0/0 = R2 S0/1
  S0/1 = R7 S0/1

###############################1-Dynamips-1#############################

###############################2-Dynamips-2#############################
[localhost:7201]
  udp=11000
  workingdir = /tmp/workingdy2

[[3725]]
  image = /tmp/c3725-adventerprisek9-mz.124-15.T13.bin
  ram = 128
  #idlepc =  ?? # We will talk about this, later.
  ghostios = true
  sparsemem = true
  idlemax = 100
  disk0=128

 [[Router R4]]
  model = 3725
  console = 2004
  autostart = false
  S0/0 = R5 S0/0
  S0/1 = R8 S0/1

 [[Router R5]]
  model = 3725
  console = 2005
  autostart = false
  #S0/0 = R4 S0/0
  S0/1 = R6 S0/0

 [[Router R6]]
  model = 3725
  console = 2006
  autostart = false
#  S0/0 = R5 0/1

###############################2-Dynamips-2#############################

###############################3-Dynamips-3#############################
[localhost:7202]
  udp=12000
  workingdir = /tmp/workingdy3

[[3725]]
  image = /tmp/c3725-adventerprisek9-mz.124-15.T13.bin
  ram = 128
  #idlepc =  ?? # We will talk about this, later.
  ghostios = true
  sparsemem = true
  idlemax = 100
  disk0=128

 [[Router R7]]
  model = 3725
  console = 2007
  autostart = false
  S0/0 = R9 S0/0
  #S0/1 = R3 S0/1

 [[Router R8]]
  model = 3725
  console = 2008
  autostart = false
  S0/0 = R9 S0/1
  #S0/1 = R4 S0/1

 [[Router R9]]
  model = 3725
  console = 2009
  autostart = false
#  S0/0 = R7 0/0
#  S0/1 = R8 0/0

###############################3-Dynamips-3#############################

We already started dynamips with 7200, 7201 and 7202 ports but dynagen service has been crashed. Some dynamips services may have been crashed. We have to check them before restarting dynages service.

ismail@ismail-ThinkPad-T410:~$ ps -ef | grep dynamips
ismail    3811  3756  1 10:15 pts/0    00:00:14 dynamips -H 7200
ismail    3829  3756  1 10:16 pts/0    00:00:14 dynamips -H 7201
ismail    4017  3756  0 10:27 pts/0    00:00:00 grep --color=auto dynamips

So One dynamips service crashed and other two ones still working. I want to kill all dynamips services and start them again to make sure about everything on the way. We can kill a PID using the "kill -9 3811" command but I selected pkill command in this sample to show first practice.

ismail@ismail-ThinkPad-T410:~$ pkill dynamips
[1]-  Terminated              dynamips -H 7200
[2]+  Terminated              dynamips -H 7201
ismail@ismail-ThinkPad-T410:~$

And now, there is no any running dynamip process. We can start all of them again,

ismail@ismail-ThinkPad-T410:~$ dynamips -H 7201 &
ismail@ismail-ThinkPad-T410:~$ dynamips -H 7202 &
ismail@ismail-ThinkPad-T410:~$ dynamips -H 7203 &
ismail@ismail-ThinkPad-T410:~$ dynagen /tmp/sample2.net 
Reading configuration file...
...
...
...
Dynagen management console for Dynamips and Pemuwrapper 0.11.0
Copyright (c) 2005-2007 Greg Anuzelli, contributions Pavel Skovajsa

=>

Finally dynagen loaded our network topology. We can handle it now. We can start routers with "start" command on dynagen console and get console of routers with "telnet Rx" command (x is number of router name, for example R4).

We may need to use the "idlepc" parameter in this sample. If you need more performance, you have to use idlepc parameter. Dynagen can optimize itself using the value given for idlepc. We have to learn only what is our idlepc value for our system. We can use following command in the dynagen console,

=> start R1
=> idlepc get R1
Please wait while gathering statistics...

Please wait while gathering statistics...
Done. Suggested idling PC:
   0x60c08128 (count=22)
   0x60c08164 (count=33)
   0x60c08180 (count=35)
   0x60c081c0 (count=66)
   0x62b2823c (count=45)
   0x60c08bf8 (count=23)
   0x60c08c20 (count=20)
   0x614b0e34 (count=38)
   0x62b2b134 (count=20)
   0x6026bca4 (count=30)
Restart the emulator with "--idle-pc=0x60c08128" (for example)
   1: 0x60c08128 [22]
   2: 0x60c08164 [33]
   3: 0x60c08180 [35]
   4: 0x60c081c0 [66]
   5: 0x62b2823c [45]
   6: 0x60c08bf8 [23]
   7: 0x60c08c20 [20]
   8: 0x614b0e34 [38]
   9: 0x62b2b134 [20]
  10: 0x6026bca4 [30]
Potentially better idlepc values marked with "*"
Enter the number of the idlepc value to apply [1-10] or ENTER for no change: 
No changes made
=>

If you find any "*" line, you can use this line value. If you don't have any marked line with "*", you can try to get idlepc value again.

Thursday, June 14, 2012

Calculating Levenshtein Distance Between Two Strings in Fuzuli

Hi! I am so happy I can code with Fuzuli programming language. In this article, I'll show you how to calculate the distance between two strings on Fuzuli. I usually use Levenshtein distance on PHP. This situation is the same on Fuzuli. Before introducing my sample, sharing the Levenshtein function would be nice, I think.

For this article, I've got an example here:
The code given belown is about how to calculate the distance between strings.

(require "nfl/io.nfl")
(require "nfl/string.nfl")

(print "Please enter a word for calculating distance: ")
(let word(readline))

(let Array (list "windows" "ubuntu" "android"))

(foreach i in Array
   (block
  (let distance (levenshtein word i))
  (print distance " for " i "\n")
    )
)

(require "nfl/string.nfl")
(require "nfl/io.nfl")

The code shown above shows how we import a required package. string package is for Levenshtein function, namely it is not "fuzuli" :) io package is for readline.

You can run it by typing:

fuzuli levenshtein.fzl

Screen View

If you compare screen views, you can see the differency. First, I wrote "fuzuli" and the system has found distances, but when I write "android", the system has found zero distance for "android".

Here, I actually wanted to show you many things. One of'em was how to get a piece of array with foreach. Other one was the point of this article, Levenshtein function. I hope that was enough and helpful for you!

See you!

Calculating roots of a parabola with Fuzuli Programming Language

Fuzuli has its core libraries inhereted from C++ standard libraries. That is why adapting to Fuzuli does not require climbing a sharp learning curve. Only the requirement is to have a habitat of parenthesis syntax.

In this article, we write a small script for calculating roots of a parabola. This script includes two Fuzuli packages, io and math. This packages are required for readline, exit and sqrt functions. The remaining part of this script uses the internal functions of Fuzuli.

A parabola is a function in form of ax^2 + bx + c where a!=0. Delta, which is calculated as b^2 - 4ac is an indicator of number of real roots. If delta is less than zero, the parabola has no real roots. If delta is zero, all of the roots shares the same value. If delta is greater than zero, there are two distinct roots. This is not our subject now and it is well described at the Wikipedia.

Before coding, you can manually install the Fuzuli for Linux or Windows systems. Please visit the Fuzuli Official Web Page and Google Code page for installing instructions.
Our Fuzuli script is shown below:

(require "/usr/lib/fuzuli/nfl/io.nfl")
(require "/usr/lib/fuzuli/nfl/math.nfl")

(print "Please enter a b and c for parabola ax^2 + bx + c\n")
(print "Enter a:")
(let a (readline))

(print "Enter b:")
(let b (readline))


(print "Enter c:")
(let c (readline))

(let delta (- (pow b 2) (* 4 (* a c))))
(print "Delta is " delta "\n")

(if (< delta 0.0)
 (block
  (print "No real roots exist\n")
  (exit 0)
 )
)

(if (= delta 0.0)
 (print "There are two equal roots\n")
)

(if (> delta 0.0)
 (print "There are two different real roots\n")
)

(let x1 (/ (+ (* -1 b) (sqrt delta)) (* 2 a)))
(let x2 (/ (- (* -1 b) (sqrt delta)) (* 2 a)))
(print "x1=" x1 " and x2=" x2 "\n")

I write the codes above in the file "delta.fzl". You can run it by typing

#fuzuli delta.fzl

and program asks for values of a, b and c. The output screen is similar to the output given below:

Have fun with Fuzuli!

Wednesday, June 13, 2012

Extracting links from web pages using Fuzuli

We have too much written about Fuzuli and its core components but we didn't publish any real world applications run on it.

Fuzuli, our new general purpose programming language and interpreter, is first introduced in Practical Code Solutions blog and has the official web page http://www.fuzuliproject.org.

Here we have an example of extracting links from an HTTP connection. Program asks for a domain name. The default one is amazon.com and processed by just pressing enter key. Then program sends an HTTP GET request to the server and reads the content. After collecting all of the content, program starts to parse HTML codes and shows the tags start with an A tag. The Fuzuli code is shown below:

# Loading required packages
(require "/usr/lib/fuzuli/nfl/io.nfl")
(require "/usr/lib/fuzuli/nfl/string.nfl")
(require "/usr/lib/fuzuli/nfl/net.nfl")

# Getting a domain name from user.
(puts "Please give a domain (for default just type enter):")
(let word (readline))

# If user did not type anything
# set the default page to amazon.com
(if (< (strlen word) 3)
   (let word "amazon.com")
)
(print "Doing " word "\n")


# Open a socket connection to host
(print "Connecting " word "\n")
(let socket (fsockopen word 80))

# Sending HTTP Request
(print "Sending request\n")
(fsockwrite socket (strcat (list "GET /\n\n")))

# Reading html content
(print "Retrieving result\n")
(def htmllist LIST)
(while 1
   (let c (fsockread socket 1))
   (if (= (typeof c) NULL) (break))
   (append htmllist c)
)
# Closing socket
(fsockclose socket)

(print "Constucting string\n")

(let html (strcat htmllist))
(let len (strlen html))
(print len " bytes read.\n")

(def part STRING)
(def i INTEGER)

# Parsing loaded content
(for (let i 0) (< i len) (inc i)
   (let part (substr html i (+ i 7)))
   (if (= part "<a href")
      (block
         (print "link found: \n")
         (while (!= part "</a>")
            (let part (substr html i (+ i 4)))
            (print (substr html i (+ i 1)))
            (inc i)
         )
         (print part "\n")
      )
   )
)

The example given above combines variable definitions and scopes, loops, sockets and basic io. Please get more detailed information about the keywords, commands and functions using Fuzuli's documentation site.

PHP and Microsoft Access Database Connection

We all know that MySQL database connection is the best way for PHP. This make us so strong during coding. But what I have to say is that is not the only way. We have some opinions about connecting to databases. These may be between PHP&Access, PHP&Sqlite and PHP&PostgreSQL etc. But here, we interested in the first one, PHP&Access.

Access is one of the most popular databases in the world. It was made by Microsoft Corporation. You can find here more information about Access. A person who uses the Access can create, update, delete, etc tables on databases without using SQL. That's why we can see easily how important the interface is. In this respect this is so simple and useful.

An Example on Access : Getting data from access

<?php

$conn = new COM("ADODB.Connection") or die("ADODB Oops!");

$conn->Open("DRIVER={Microsoft Access Driver (*.mdb)};DBQ=C:\Users\UserName\Desktop\ MyDatabaseFile .mdb");

$data = $conn->Execute("SELECT * FROM myTable ORDER BY users ASC");

print "<TABLE border='1'><TR><TD colspan='6'>DATA</TD><TR>";

while (!$data->EOF)

{

print "<tr>";

print "<td>" . $ data ->Fields[0]->value . " </td>";

print "<td>" . $ data ->Fields[1]->value . " </td>";

print "</tr>";

$ data ->MoveNext();

}

echo "</TABLE>";

Just save code above as access.php and run it. It's going to be like the screen belown.

Screen View

If you try to figure that out, codes belown will be helpful for you.

$conn = new COM("ADODB.Connection") or die("ADODB Opps!");

$conn->Open("DRIVER={Microsoft Access Driver (*.mdb)};DBQ=C:\Users\UserName\Desktop\MyDatabaseFile.mdb");

We try to connect access database with php here.

odbc_connect(‘dsn name’, ‘user name’, ‘password’);

There is a problem with this! When you look at the code belown, can realize user_name and password field. What are these ones? How can we build on these? That's the point on this article actually. Just go to the localhost and this page:

phpinfo.php

<?php

Phpinfo();

When run phpinfo.php file, need look into ODBC properties

ODBC with phpinfo.php

You must implement your user name and password for working on it. By the way, it is easier to make this operations with codes. That's why i show you as code, not screen views.

Well, let's code then :)