Database schemas Databases are present in almost all kinds of application that need to store information in some form or the other. Web applications like blogs, cms, social networking sites or business applications etc all have a database along with the code. The database design or schema determines how the tables and their relationships are… Read More »
SSL certificates Some websites, specially restricted ones might require you to use a client side ssl certificate to open the pages. The certificate is used as an authentication factor, in place of username/password. When opening such websites in browsers, the browser must provide the ssl certificate. Over here we shall see how to do that… Read More »
Socket based chat application In our previous article on we learned about the basics of creating a socket server and client in python. In this post we are going to write a very simple chat application in python that is powered by sockets. The chat application we are going to make will be more like… Read More »
The telnet client is a simple commandline utility that is used to connect to socket servers and exchange text messages. Here is an example of how to use telnet to connect to google.com and fetch the homepage. $ telnet google.com 80 The above command will connect to google.com on port 80. $ telnet google.com 80… Read More »
ICMP Ping Flood A ping flood program sends a large of icmp packets to a remote host to flood the network and system resources on the target system. The target system keeps replying to the icmp packets and its system resources are consumed un-necessarily. In a previous article on we saw how to construct raw… Read More »
ICMP Ping Flood Icmp ping flood is a kind of DOS attack that can be performed on remote machines connected via a network. It involves sending a large number of ping echo requests (packets) to the target system such that it is not able to tackle so fast. So the result is that the host… Read More »
Communication over sockets involves 2 programs running on the same machine or on separate machines across a network. First is a socket server and the other is a socket client. Tcp stands for Transmission control protocol and it is the most common protocol being used for most of the network communication that takes place over… Read More »
SOAP and PHP SOAP is a protocol to exchange objects over http. It is used to implement apis and the data being exchanged is in xml format. Sometimes it might be required to modify the soap request to add custom http headers for example. Since SoapClient is a class, it can be extended and the… Read More »
When loading xml files in php through simplexml_load_string or domDocument class, sometimes an error like this might popup Warning: DOMDocument::loadXML(): Input is not proper UTF-8, indicate encoding ! OR Warning: simplexml_load_string(): Entity: line 93: parser error : Input is not proper UTF-8, indicate encoding ! The error occurs when the xml has some invalid characters… Read More »
Many applications do not directly support the use of socks proxy. It is not possible to configure them in anyway to use a proxy server. Torsocks enables such applications to use the Tor Socks proxy. It automatically routes all network requests made by a certain application through the Tor proxy. The manual page defines Torsocks… Read More »
The file_get_contents function is often used to quickly fetch a http url or resource. Usage is very simple and appears like this $content = file_get_contents('http://www.google.com/'); However the file_get_contents does not get the contents compressed. It requests the server to send everything in plain text format. Most websites are capable of serving compressed content, if they… Read More »
Socket Programming Socket programming involves connecting to remote machines on LAN or over the internet using ip addresses and port number. For example google.com has an ip “173.194.36.3” and runs http server on port 80. So a socket application can connect to that ip address on that particular port number and start data communication. Socket… Read More »
In your web application you might need to parse the user’s user-agent string to find out the browser/OS/device being used. This is necessary specially when your webapp tries to adapt to the user’s platform in a better way. For example a different layout for mobile device or restricted features/graceful degradation on a non supporting browser…. Read More »
The filter_var function of php is capable of validating many things like emails, urls, ip addresses etc. It does not have a direct option to validate a domain name however. So I coded up this little snippet that the filter_var function with a little tweak so that it can validate domain names as well. function… Read More »
Download a File using Curl Here is a quick curl snippet for php, that can download a remote file and save it. <?php set_time_limit(0); // File to save the contents to $fp = fopen ('files2.tar', 'w+'); $url = "http://localhost/files.tar"; // Here is the file we are downloading, replace spaces with %20 $ch = curl_init(str_replace(" ","%20",$url));… Read More »
Adsense Management API The google adsense management api can be used to fetch adsense reports inside a web or desktop application. In this article we are going to see how to use the api in python to fetch the earnings. The documentation is available here. The code shown here is build using the samples. Setup… Read More »
Html to pdf If your php application needs to generate some kind of pdf report then the simplest approach would be to generate the report as an html and then convert it to pdf using some library. Plenty of libraries are available that can convert html to pdf in php. To name a few -… Read More »
Php applications might need to do some image processing if they are allowing users to upload pictures of somekind. This can include cropping, watermarking, compressing etc. To compress an image the quality needs to be adjusted. Here is a code example of how to do it: function compress_image($src, $dest , $quality) { $info = getimagesize($src);… Read More »
In a previous article we learned how to . Now lets do the reverse, that is extract tar.gz archives and get the files out. The code to extract a tar.gz archive is very simple and uses PharData class. Here is an example // decompress from gz $p = new PharData('files.tar.gz'); $p->decompress(); // creates files.tar //… Read More »
Tar is a common archive format used on linux. Alone it is just an archiving format, that is it can only pack multiple files together but not compress them. When combined with gzip or bzip2 files are compressed as well. Then it becomes a .tar.gz which is actually a gzip compressed tar file. Php has… Read More »