I upgraded my ubuntu few hours back from 11.04 to 11.10 ; it all went fine. After the upgrade I noticed that Quanta – my favorite php development tool had vanished. Doing few searches on google lead to the information that its now deprecated and not maintained in the repos anymore. So I got it… Read More »
The function gettimeofday can be used to retrieve the total number of seconds and balance microseconds elapsed since EPOCH. Structure timeval looks like this : struct timeval { time_t tv_sec; /* seconds */ suseconds_t tv_usec; /* microseconds */ }; On Linux it can be done like this : /** * Get time difference in microseconds… Read More »
On Linux the header file sys/types.h provides the fixed sized integer data types like these : u_int8_t; u_int16_t; u_int32_t; On windows the header file stdint.h provides similar ones but with slightly different names , uint8_t etc. So if you are writing cross platform code you can get the same ones on windows as in a… Read More »
Theory The whois information of an ip address provides various details like its network, range, isp etc. This information is maintained by various regional registry servers. Read the wikipedia article on regional internet registries for more information. There are a total of 5 regional registries spanning various geographical regions of the world. For example if… Read More »
wxwebconnect is a control for wxwidgets that allows to embed a gecko browser in a wxwidgets application. So lets try to install it on Ubuntu 11.04 wxWidgets can be installed from synaptic. Look for packages called libwxgtk2.8-* 1. Download wxwebconnect source from http://www.kirix.com/labs/wxwebconnect/downloads.html Extract them in home directory. Inside the webconnect directory you would see… Read More »
Socket programming with winsock This is a quick guide/tutorial to learning socket programming in C language on Windows. “Windows” because the code snippets shown over here will work only on Windows. The windows api to socket programming is called winsock. Sockets are the fundamental “things” behind any kind of network communications done by your computer…. Read More »
Handle multiple socket connections When writing server programs using sockets , it becomes necessary to handle multiple connections at a time , since a server needs to serve multiple clients. There are many ways to do so. On linux this can be done in various ways like forking , threading , select method etc. In… Read More »
Learn socket programming in C on the linux platform. Write socket servers and client programs in C.
Wxpython is the python port of wxwidgets gui library. On ubuntu wxpython can be installed from synaptic. On windows it can be downloaded from the website wxpython.org And here is a small program that pops up a simple window , to take a domain name and perform a whois for that domain. #!/usr/bin/python ''' GUI… Read More »
Whois A whois client is a program that will simply fetch the whois information for a domain/ip address from the whois servers. The code over here works according to the algorithm discussed here. A whois server runs a whois service on port 43 (whois port). We need to connect to this port with sockets and… Read More »
Php has a useful function called str_replace which can search and replace a certain string in another big string. However there is no such function in C. So I wrote up one for myself. Here is the code. /* * Search and replace a string with another string , in a string * */ char… Read More »
Here are some IDEs that work very well on Ubuntu ( and other Linuxes ) and can be used as an alternative to the terminal gcc or g++ thing. Geany Url : http://www.geany.org/ Install with sudo apt-get install geany Open any C/C++/PHP/Html/Python/Perl file and start coding. Compile with F8 , Build with F9 and execute… Read More »
Local Ip address The local ip is the source ip in IP packets send out from a system. When the system is a part of a local area network then the local ip in most cases is something like 192.168.*.* . The network interface (eth0) is assigned an ip address of that range. However when… Read More »
Winpcap Winpcap is a packet capture library for Windows used for packet sniffing and sending raw packets. Wireshark is a popular sniffer tool that uses winpcap to sniff packets. Here is a sample code which shows how winpcap can be used to sniff incoming packets on a particular interface. Code /* Simple Sniffer with winpcap… Read More »
MAC Address Mac address (Media Access Control Address) or hardware address is a 48 bit (6 character) wide address assigned to a network interface. It is important for the packet delivery between 2 devices like your computer and the router. Ethernet protocol uses the mac address to deliver it to the right network node. It… Read More »
The traceroute utility can be installed from synaptic : $ sudo apt-get install traceroute Some Information : $ traceroute -V Modern traceroute for Linux, version 2.0.15, Oct 17 2010 Copyright (c) 2008 Dmitry Butskoy, License: GPL v2 or any later Doing some test runs $ traceroute www.google.com traceroute to www.google.com (74.125.235.20), 30 hops max, 60… Read More »
Socket applications often need to convert hostnames like google.com to their corresponding ip address. This is done through dns requests. The socket api in linux provides functions like gethostbyname and getaddrinfo that can be used to perform the dns requests and get the ip address. 1. gethostbyname The first method uses the traditional gethostbyname function… Read More »
MPM (Multi processing module) is a component of apache server, that determines how multiple clients or connections shall be handled. Apache is flexible by design and there are different mpms that can be used with apache depending on the needs. Some MPMs create a separate process to handle each request, whereas some create separate threads…. Read More »
Linux distro name and version When working with an unknown server, the first task of a sys admin is to gather some information about the system, like what OS is it running, what version, what services are running and so on. And there is no single command that can detect distribution specific information consistently across… Read More »
Install mpm itk On ubuntu mpm itk can be installed from synaptic. Look for the package called apache2-mpm-itk sudo apt-get install apache2-mpm-itk Configure Configuration for mpm itk can be done in the file sites-enabled/000-default $ gksudo gedit /etc/apache2/sites-enabled/000-default In the VirtualHost *:80 section add this just before the end of the VirtualHost tag [xml] <IfModule… Read More »