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 »
Raw UDP sockets Raw udp sockets are used to constructed udp packets with a application defined custom header. It is useful in security related network applications. The udp header can be found in RFC 768 and has a very simple structure as shown below. 0 7 8 15 16 23 24 31 +——–+——–+——–+——–+ | Source… 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 »
UDP sockets This article describes how to write a simple echo server and client using udp sockets in C on Linux/Unix platform. UDP sockets or Datagram sockets are different from the TCP sockets in a number of ways. The most important difference is that UDP sockets are not connection oriented. More technically speaking, a UDP… Read More »
Learn socket programming in C on the linux platform. Write socket servers and client programs in C.
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 »
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 »
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 »
TCP/IP 3-way handshake is done to establish a connection between a client and a server. The process is : 1. Client –SYN Packet–> Server 2. Server –SYN/ACK Packet –> Client 3. Client –ACK Packet –> Server The above 3 steps are followed to establish a connection between source and destination. SYN Flood DOS attacks involves… Read More »