Syn Flood Syn flood program sends out a large number of syn packets to a destination host such that the destination host gets under heavy pressure to reply to all of them and hence consumes huge amount of memory/cpu resources without any real purpose. This causes the services of the remote host to become unavailable… Read More »
Syn flood and raw sockets A syn flood program sends out large number of tcp syn packets to a remote host on a particular port number. Syn packets are intended to initiate a tcp connection. However if a large number of syn packets are send without any purpose, then then it would consume a lot… Read More »
Tcp/IP Socket programming Sockets enable your program or application to talk to other machines over the network. When you type in google.com in your browser, it talks to google.com over the internet and fetches the webpage. For socket programming we need to use the socket library or api which provides some very simple functions to… Read More »
Tcp connect port scanner in perl A tcp connect port scanner works on the principle of establishing a full tcp connection on a port it wants to check. Therefore a port scanner is quite easy to code, as it just connects to all required ports one by one and whenever a connection is established, reports… Read More »
Open ports When doing a lot of socket programming, it often happens that a server program when recompiled/rerun fails to bind to a particular port number because that port number is already in use. To close the port number manually first the process name/id has to be found out that is holding the port open… Read More »
UDP – User Datagram Protocol sockets UDP is an alternative protocol to the more commonly used TCP protocol. It is a connection-less protocol where you directly send packets without have to establish a proper connection. UDP packets have smaller headers compared to TCP headers. Also data communication is faster since no acknowledgement is exchanged for… Read More »
Pcapy In the previous articles we coded packet sniffers in python using raw sockets. Now lets use the libpcap library for the same. Libpcap is the packet capture library for linux and has wrappers for most languages. In python there are multiple libpcap wrappers like pcapy, pypcap etc. In this article we shall use the… Read More »
Wrapper class for socket functions The standard socket library in C comes with a lot of functions for every task like connecting, sending data and receiving data etc. However knowing the syntax of all the functions and calling them again and again and in the right sequence could be a bit intimidating. Using a class… Read More »
Socket function – recv() If you are writing a network application using sockets in C that communicates with a remote server and fetches data, then you must be aware of the recv function that is used to receive data. The recv function can only receive a specified number of bytes in the response. If the… Read More »
UDP Sockets in Php In a previous article we learnt about writing simple server and clients using TCP sockets in php. In this article we are going to use udp sockets for the same. UDP sockets are much simpler to work with since they are connection-less. A udp server just has an socket that waits… Read More »