The Raw socket code based on UDP protocol can be seen at this Link. We directly send the packet to the destination address via “sendto” API. As was seen in the TCP code for Raw sockets, we need to create the UDP header in the application and send the header alongwith the packet data. The […]

This article deals with a RAW socket example for the IPPROTO_UDP protocol. The interested reader can get an understanding of TCP/UDP headers at this link. The code is shown below Analysis of Raw Socket IPPROTO_UDP Socket code

The Raw socket code can be viewed at this location. It is seen that the Raw socket does not bind or connect to the destination location. We use “sendto” API to send data to the destination IP address and use “recvfrom” API to receive data on the destination IP address. The socket is opened with […]

The following code opens a raw socket with the IPPROTO_TCP L4 protocol. By opening such a socket connection, The TCP header now needs to be filled in by the application. The IPv4 header will still be filled by the Kernel on the packet send if IP_HDRINCL flag is not set via setsockopt API. The code […]

In this article, we look at certain aspects of TCP/UDP/IP headers which we would most likely be used in the coming example implementations for Raw socket for TCP/UDP protocols in this website.  Kindly note that this article does not try to explain the TCP/UDP/IP headers in detail, but only tries to provide context to the […]

In the Previous article (Link here), we looked at how Raw sockets are invoked and how Raw sockets allow an application to directly access lower layer protocols or create it’s own L4 protocol on top of the IP layer. What does the above statement mean? We look at a diagram below (taken from the book […]

Normally the TCP/UDP sockets provide an abstraction wherein the user of those sockets does not need to concern himself/herself with the TCP/IP or layer 2 headers. The data is provided to the socket with all the lower layer headers removed. But what if some one wished to tweak the IP headers themselves. If a developer […]

Linux supports the SOCK_SEQPACKET socket connection for AF_UNIX domain. The Sequenced socket SOCK_SEQPACKET code is exactly similar to AF_UNIX TCP stream socket code.  The only difference is that the “type parameter” of the socket API is passed SOCK_SEQPACKET as the type. The code analysis for the TCP Stream socket can be seen at this link […]

Sequenced Packet Socket connections are connection oriented sockets. The normal socket connection APIs such as bind/listen/accept/connect are used to establish a socket connection. In all respects, as far as the connection establishment is concerned, it is equivalent to a TCP stream socket connection. The SOCK_SEQPACKET socket connection has the below properties: The TCP stream socket […]

Till now we have seen examples wherein the socket connection is between two distinct processes. “socketpair API” socket connection allows a user to create a socket link between a Parent process and it’s child process. Each process (ie. the parent and its child) gets two handles. The parent socket handle and the child socket handle. […]