Category : "Socket Programming"

Socket programming tutorials in C, Python, Perl, Php, Java and Winsock

Get ip address from hostname in C using Linux sockets

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. gethostbyname The first method uses the traditional gethostbyname function to retrieve information about a hostname/domain name. Code #include<stdio.h> //printf #include<string.h> ...

Packet Sniffer Code in C using Linux Sockets (BSD) – Part 2

In the previous part we made a simple sniffer which created a raw socket and started receiving on it. But it had few drawbacks : 1. Could sniff only incoming data. 2. Could sniff only TCP or UDP or ICMP or any one protocol packets at a time. 3. Provided IP frames , so ethernet headers were not available. In this article we are ...

Code a network packet sniffer in python for Linux

Basic Sniffer Sniffers are programs that can capture/sniff/detect network traffic packet by packet and analyse them for various reasons. Commonly used in the field of network security. Wireshark is a very common packet sniffer/protocol analyzer. Packet sniffers can be written in python too. In this article we are going to write a few very simple sniffers in python for the linux ...

Code a TCP Connect port scanner in PHP

A port scanner is a software application designed to probe a server or host for open ports. We earlier made a TCP Connect port scanner in C here - http://www.binarytides.com/blog/tcp-connect-port-scanner-code-in-c-with-winsock/ and here - http://www.binarytides.com/blog/tcp-connect-port-scanner-with-linux-sockets-bsd/ Now we shall try making the same in PHP. The code is very simple : Using fsockopen <?php /* Simple TCP connect port scanner in php using fsockopen */ //avoid warnings like ...

DNS Query Code in C with linux sockets

This article is an extension of the article : http://www.binarytides.com/blog/dns-query-code-in-c-with-winsock/ The Linux version has some changes. On Linux the dns server ips are stored in a file called /etc/resolv.conf. So the get_dns_servers function will open this file and pickup the dns server ip addresses. A typical /etc/resolv.conf file can look like this : # Generated by NetworkManager nameserver 208.67.222.222 nameserver 208.67.220.220 So the lines starting with nameserver can ...

Code raw sockets in C on Linux

Raw tcp sockets in C Raw sockets can be used to construct a packet manually inside an application. In normal sockets when any data is send over the network, the kernel of the operating system adds some headers to it like IP header and TCP header. So an application only needs to take care of what data it is sending and ...

SYN Flood DOS Attack with C Source Code (Linux)

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 sending too many SYN packets (with a bad or random ...

TCP Connect Port Scanner Source Code in C with Winsock

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 the connect() function would simply timeout ...

Code a port scanner in C | linux

Tcp connect port scanning Tcp connect port scanner works by trying to establish a connection with every port that is to be scanned. If a connection is established then the port is open otherwise closed. This technique of port scanner is the most basic form of port scanning. However it is the slowest and not very stealthy and easily caught by ...

C Packet Sniffer Code with libpcap and linux sockets

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 and compile it and install. Or if ...

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