A port scanner is a program designed to probe a server or host for open ports. Looking at open ports, one can tell what services might be running on the remote server. We earlier made a TCP Connect port scanner in C here – https://www.binarytides.com/tcp-connect-port-scanner-code-c-winsock/ and here – https://www.binarytides.com/tcp-connect-port-scanner-c-code-linux-sockets/ Now we shall try making the… Read More »
Here is a list of port scanners that work on Ubuntu/Linux. 1. Angry IP Scanner Download and Install from http://www.angryip.org/ Fast and easy to use network scanner and port scanner. To scan ports got to Tools > Preferences > Ports > Port Selection Enter the ports you want to scan Start the scan. 4. Nmap… Read More »
The getimagesize function of php provides lot of information about an image file , including its type. The type can be used to check if the file is a valid image file or not. To check if a file is an image or not, use the function function is_image($path) { $a = getimagesize($path); $image_type =… Read More »
In many php applications there are multiple tasks that need to be run via cron at different times. In a typical application you may be doing the following tasks via cronjobs : 1. Backup database. 2. Send out email to subscribers. 3. Clear temporary files. 4. Fetch xml feeds from some source and store them… Read More »
desktop:~$ php -a Interactive shell php > echo time(); 1319362432 php > Above is an example of a given timestamp. And a cron schedule can look like this 0 5 * * * – which means run everyday at 5 hours and 0 minutes. Now in a php application you may need to test if… Read More »
The strtotime function is used to convert a date in various formats to a timestamp. However its behaviour is different based on architecture it is running on, whether 32bit or 64bit. Lets take a few examples : In 64 bit environment desktop:~$ php -a Interactive shell php > echo strtotime("0000-00-00 00:00:00"); -62170005200 php > echo… Read More »
In a previous article we saw how to . Now here we shall see how to perform a whois for an ip address from the terminal. Get your ip address from ipmango.com. I got this IP : 59.93.210.154 Little Theory The information about any ip or ip range is stored in the Regional Internet Registry…. Read More »
Whois is often used to find out the details of the owners or the registrants of a domain name. The details includes name, address, telephone number etc. Whenever a domain is registered by a user, the user has to fill out own details at the domain registrar. These details are fed into the whois system,… Read More »
The autoincrement feature in mysql allows us to create numeric fields that automatically increment by 1 for every row inserted. It does it atomically so we don’t have to worry about any duplicates or collision. However, there are situations when we need an autoincrement field to reset at regular intervals like every month or so…. Read More »
If a file is to be saved in at path /var/www/a/b/c/d/abc.zip where the directory c and d dont exist then the directories have to created. Here is a function that uses recursion to check for directories in a path and create them if they do not exist : /** Make a nested path , creating… Read More »
Box2d Box2d is a 2d physics simulation library written for C++ and ported to many languages including Javascript. From Box2d’s Website Box2D is a feature rich 2D rigid body physics engine, written in C++ by Erin Catto. It has been used in many games, including Crayon Physics Deluxe, winner of the 2008 Independant Game Festival… Read More »
DNS Query Code in C A dns query lets you to lookup the various dns records for a given hostname or domain name on the internet. The simplest use case is to lookup the ip address of a domain name. When you open a url in your browser, it first performs a dns query to… Read More »
PHP’s session_start method stores the session data in files by default. These files are stored in the tmp directory of the OS and are cleared at intervals by the garbage collector. Alternatively the session data can be stored in database as well. Storing session data in database has certain advantages : 1. Limit the number… Read More »
Php from command line PHP scripts are usually opened in a web browser. But they can be run from command line or terminal as well. The syntax to run a script from commandline is very much similar to python or perl. php /path/to/script/index.php Inside a script it might be necessary to test if it is… Read More »
Racing car in box2d Box2d is a physics 2d simulation library and is used in game development. Apart from C/C++ it has ports for various languages like python, javascript etc. With the availability of the html5 canvas element and many other html5 apis, it becomes possible to write browser based games in javascript. So in… Read More »
To get beautiful and smooth fonts on Ubuntu : 1. Install ttf-mscorefonts-installer from synaptic This will provide the fonts like microsoft arial , tahoma , verdana , courier etc. 2. Get the xml file by Obi Bok from https://wiki.ubuntu.com/Fonts The above xml file provides special finetuned settings for antialiasing and hinting parameters for various fonts… Read More »
If Totem , the default movie player does not play vcds properly , showing file permission errors , then try : 1. SMPlayer Install from synaptic : sudo apt-get install smplayer 2. mplayer Install from synaptic : sudo apt-get install mplayer 3. KPlayer Install from synaptic : sudo apt-get install kplayer To play from terminal… Read More »
Google Chrome has problem displaying hindi/unicode and other Indian language fonts. For example bold hindi fonts might be displayed as square boxes. http://code.google.com/p/chromium/issues/detail?id=32109 http://code.google.com/p/chromium/issues/detail?id=21320 It is some kind of font selection bug. Lets try fixing it. 1. You may want to install the packages ttf-devanagari-fonts and ttf-indic-fonts. Also get that mangal.ttf thing from windows or… Read More »
VCDs that are played on vcd players often contain the video in dat format. The dat format is internally mpeg only but has some additional header information attached. So the mpeg portion has to be ripped off to get the mpeg format. Once converted to mpeg format, it can be processed inside any video editor…. Read More »
Resizing images Web applications often need to work with images like pictures of users or photos etc. So the need to resize images comes up when creating thumbnails for example or compressing images for storage. The default library to handle image operations in php is GD. It can be used to resize images. GD vs… Read More »