Tcp connect port scanning TCP connect() scanning is the most basic form of TCP scanning. The program performs a connect() command on those ports of the target machine which are to be checked. If the port is open then the connect() command will succeed and a connection will be established. If the port is closed… Read More »
Port scanning A port scanner is a program that checks for open network ports on a local or remote machine. For example, if a machine is running an http webserver then it has port 80 open. So by scanning for open ports on a machine, we can find what server applications are running on it…. Read More »
The following function will parse a given text and convert all the urls into links. It does this using regular expressions. It converts email addresses to mailto links as well. Code function parse_links($str) { $str = str_replace('www.', 'http://www.', $str); $str = preg_replace('|http://([a-zA-Z0-9-./]+)|', '<a href="http://$1">$1</a>', $str); $str = preg_replace('/(([a-z0-9+_-]+)(.[a-z0-9+_-]+)*@([a-z0-9-]+.)+[a-z]{2,6})/', '<a href="mailto:$1">$1</a>', $str); return $str; }
Libpcap Libpcap is a packet capture library for linux which can be used to sniff packets or network traffic over a network interface. Pcap Documentation gives a description of the methods and data structures available in the libpcap library. To install libpcap on your linux distro you can either download the source from the website… Read More »
Packet sniffer Packet sniffers are programs that intercept the network traffic flowing in and out of a system through network interfaces. So if you are browsing the internet then traffic is flowing and a packet sniffer would be able to catch it in the form of packets and display them for whatever reasons required. Packet… Read More »
Switches, Routers, Wires and speed As usual internet was fast on ubuntu as it used to be till I needed to plug more PCs into the adsl route lying nearby. After connecting all computers and the adsl router to a switch I noticed that on one of the PC (Ubuntu 8.04) internet became really slow…. Read More »
Install Postgresql , phpPGAdmin and pgadmin 3 can be installed from synaptic. $ sudo apt-get install postgresql phppgadmin pgadmin3 After installation some configuration needs to be done. First of all setup the password of the user ‘postgres’ which is the default user of postgresql. Type the following in the terminal $ sudo -u postgres psql… Read More »
Automatic Running In a web application there are many cases, when a certain piece of code or script needs to run automatically in the background to perform certain tasks, without the need of any user to start it. Like scraping, extracting or crawling data from web or perform some regular tasks like sending emails, system… Read More »
The PHP function set_time_limit is used to set a time limit on the maximum execution time of a script. But if the script has socket operations using fsockopen , fread and fwrite or even CURL then the set_time_limit may not appear to have any effect on the scripts timelimit or timeout. Again if safe mode… Read More »
Apache Mod Rewrite mod_rewrite is an apache module which enables rewriting of urls requested by client before the pages are fetched by apache. For example www.site.com/products.php?code=459 can be written as www.site.com/products/459 or www.site.com/products/459.html. The second url is re-written into the first one by mod_rewrite using rewrite rules specified in the .htaccess file. Enable Mod Rewrite… Read More »