The scenario is pretty simple: Using TCP/IP I have a client which connects to me (server) I want to forward the data the socket sends me to another socket which I opened and the data I received from that socket backwards.Just like a proxy. Right now I have 1 thread one who listens from incoming connection and…
Tag: sockets
Linux/Unix Socket Self-connection
When a client try to connect to a server, if client and server are both localhost, self-connection may happen(source port and destination port happened to be the same.). But my problem is, client is not listening to that port, how can self-connection be possible? Answer We can simple reproduce this phenomenon…
connect() returns “Operation now in progress” on blocking socket?
I have a blocking socket (at least it appears so in following code): And this is from log: Mar 6 10:42:04 tcpclient: fcntl ret=0, ret & O_NONBLOCK = 0 Mar 6 10:42:04 tcpclient: after select fcntl ret=0, ret & O_NONBLOCK = 0 Mar 6 10:42:14 tcpclient: authenticate: error on connect -> Operation now i…
What should TCP/IP do if one computer changed its IP address which we are sending data to?
What’s the standard behavior of TCP/IP protocol stack when a computer which we are sending data to suddenly changed its IP address? When this happens, the ARP table in our system is out of date, but the entry for this IP is not timed out? Is there a way to discover the new IP-mac mapping or we simply dr…
Is it possible that Accept return a same socket value for different tcp connections on the same machine
Is there possible that accept() (on redhat Enterprise 4/linux kernel 2.6) return a same socket value for different tcp connections from the same process of a same application and same machine? I am so surprised that when I got such a result that many connections have the same socket value on server side when …
How to prevent kernel from passing packets to network layer?
Frames received by the network card will be handled by the driver and then passed to the upper layer of the protocol stack by the Linux kernel. Is there an easy way to prevent the kernel from passing packets to network layer? So that I can receive the frames from datalink layer and handle all the packets by m…
How to completely destroy a socket connection in C
I have made a chat client in linux using socket, and i wish to destroy the connection completely. Following is the relevant portions of the code: but the close(sock) doesnot seem to close the destroy the connection completely, because after going to ‘label’ the code is exiting showing the error me…
Can Python select what network adapter when opening a socket?
The target machine running the python application will have three network interfaces available to it. In general all three networks will be vastly different, however there is a possibility that two of the three could be on similar networks. In the example below I do not have control over the destination addre…
Simplest way to script slowly sending data through a socket connection
I need to periodically connect to a server from a Linux client and send some commands, so I wrote this script: The problem is that I need to wait between commands. This script sends the commands and disconnects too quickly, which the server detects, and drops the commands. It works if I open the connection fr…
Socket data length questions
I have a couple of questions related to the following code: The questions: Why I read 255 not 256 ? Let’s say I want to send the word: “Cool” from the client to the server. How many bytes should I write “in client” and how many bytes should i read “in the server”? I&#…