is a data communications endpoint for exchanging data between processes executing within the same host operating system.

learn more… | top users | synonyms

9
votes
4answers
5k views

Are FIFO, pipe & Unix domain socket the same thing in Linux kernel?

I heard that FIFOs are named pipes. And they have exactly the same semantics. On the other hand, I think Unix domain socket is quite similar to pipe (although I've never made use of it). So I wonder ...
6
votes
4answers
5k views

How does the server find out what client port to send to?

As I understand it this is what happens when a client makes a connection request: The server will be bound to a particular port number. The port number is always bound to a listening process. Since ...
4
votes
2answers
581 views

Cross-process dup on Linux

I'd like to dup a file descriptor running in an unrelated process on Linux. I know about sendmsg(2) and SCM_RIGHTS (e.g. ...
0
votes
2answers
89 views

Why flipping is done on data from Big endian before storing in LE?

Simple but confusing question for a beginner. Suppose A is a BE machine and is sending 0x44332211 sending data to B which is LE. By default A will be using htonl of 0x44332211 which is nothing but ...
0
votes
1answer
986 views

How to connect to port immedeately, avoiding socket_bind(): unable to bind address?

When running a code that is supposed to read from a TCP/IP port I often get the following message (depending exactly what language have been used): socket_bind(): unable to bind address I know that ...
1
vote
1answer
142 views

Communication to device is lost when network starts on boot up?

I have an application that opens a socket on port 4444 to a device (/dev/linkToDevice). The "linkToDevice" is a link to ttyUSB0. The application is a c++ program of which is now a daemon and runs at ...
2
votes
1answer
78 views

Custom application running on embedded device - do I need to register my listening port in /etc/services?

I have written an application that will run on an embedded device. The installation is very minimal and uses busybox and not many other things. Part of the software includes a listener thread that ...
-1
votes
3answers
529 views

telnet implementation using C [closed]

The program in general is I want to implement telnet program. On the client side user send its logging name and password, and if it is correct he starts to send commands to the server On the Server ...
2
votes
1answer
1k views

Why can't I use strace with rsh?

If I run rsh, it works, but prints some strange “Connection refused” messages at the beginning: $ rsh localhost pwd connect to address 127.0.0.1 port 544: Connection refused Trying krb4 rsh... ...
0
votes
2answers
254 views

Physical layer header is not present in the data read from raw sockets?

i have read about RAW sockets that they are UNIX domain sockets and don't generally go over the wire unlike TCP or UDP. They are used for interprocess communication. Also they are used in the ...
5
votes
1answer
362 views

In bash, can I asynchronously open sockets and use them later?

I had no idea that Bash supported so many advanced features! I started working on a simple network program to try and use some of these things I found. My particular program is a basic redis client ...
2
votes
0answers
269 views

Best location and permissions for socket files [duplicate]

I will have a couple of WSGI applications. They will communicate with nginx using sockets. For that purpose I've created the directory /run/wsgi in which I will place all the socket files that are ...
1
vote
1answer
936 views

Default value for SO_RCVTIMEO option on Solaris

Is there any way to find out what is the default value set for option SO_RCVTIMEO on Solaris 10? If there is a way to find out how would one go about changing it? P.S. I am aware of ability of ...
2
votes
0answers
185 views

How do you write test cases for a web server that uses posix sockets? [closed]

I know how to test it experimentally by running the program, but ideally I would like to test each function I write as I write it. Usually I can't test my functions until I write a whole bunch of ...
0
votes
1answer
683 views

pcap and raw socket [closed]

I want to develop an application (module or user-level if possible) to create a raw socket in RHEL stealing all level-2 packets directly from kernel (without being routed or handled by other open ...
1
vote
0answers
903 views

Symbolic link to a socket

From a security point of view, is it safe to create a symbolic link to a socket file? The following bits of context refer to the deployment of a web application on a shared hosting service. $ ls -al ...
2
votes
1answer
2k views

Adjusting rsync TCP timeout

I'm using rsync in my own C++ program by issueing the command system("rsync -rauzvq root@host:/folder"); I use this for keeping multiple systems in sync. Now I have the problem that when a remote ...
1
vote
1answer
856 views

Where to locate “sockets”

I am new to this, so sorry if its obvious. I am running a Debian server and installing the likes of UWSGI, NGinx etc on there. The configurations keep talking about pointing to "sockets". In the ...
2
votes
1answer
877 views

Closing socket connection on running console application

I am testing a chat bot and want to gracefully handle for times when the chat server isn't running so it can come back up when the service is available again. I have the programming handled. My ...
4
votes
2answers
5k views

File descriptor linked to socket or pipe in proc [duplicate]

Possible Duplicate: /proc/PID/fd/X link number i have a question regarding the file descriptors and their linkage in the proc file system. I've observed that if i list the file descriptors ...
1
vote
1answer
715 views

Netstat shows programs running on different ports then they should

I have some code I'm testing. Program A listens on a predefined socket for program B to connect to and for my testing I'm running 32 instances of the programs A and B. I've written my script to tell ...
0
votes
2answers
790 views

Force getaddrinfo to use IPv4

The man page says: The getaddrinfo(3) function is not limited to creating IPv4 socket address structures; IPv6 socket address structures can be created if IPv6 support is available. These ...
2
votes
1answer
225 views

Why does this simple Perl client not work?

I am fairly new to IPC with sockets and expect this issue is a simple one to resolve. I'm trying to understand why I cannot get this example script from perldoc perlipc to run on my Ubuntu setup: ...
3
votes
1answer
4k views

Kill TIME_WAIT sockets immediately?

Is there anyway to kill those TIME_WAIT sockets immediately ? e.g output of netstat: tcp 0 0 127.0.0.1:8080 127.0.0.1:41500 TIME_WAIT - tcp 0 ...
2
votes
2answers
2k views

Size of data that can be written to / read from sockets

I was wondering if there is an easy way to find the maximum size that is supported by Linux sockets? (Is this configurable? If so where?) For example, most of the socket examples found on the web ...
3
votes
1answer
402 views

User associated with a socket

I use ss -p to see TCP sockets information. But process info are not printed for some sockets. Below: $ ss -p4 State Recv-Q Send-Q Local Address:Port Peer Address:Port ESTAB 0 0 ...
1
vote
1answer
387 views

How to limit all tcp traffic to the network interface the session was initiated on?

I have an embedded linux system with two network interfaces (lan0, wlan0) that are configured to the same subnet. A server on this system accepts tcp connections on both interfaces. How I can assure ...
2
votes
0answers
346 views

Does epoll give available bytes to read or write, and threshold feature?

kqueue gives available bytes to send or receive if file descriptior (such as socket) gets signal. and, kqueue gives threshold feature, for example, it does not signal until sufficient bytes are ...
5
votes
2answers
3k views

Write inside a socket open by another process in Linux

Is it possible on Linux for a process to write inside a socket open by another one? Let's say I open a connection to google.com using netcat: myuser@linux:~$ nc google.com 80 Now I can lookup for ...
13
votes
1answer
2k views

Kernel socket structure and TCP_DIAG

I'm working on a software which connects to a Real Time data server (using TCP) and I have some connections dropping. My guess is that the clients do not read the data coming from the server fast ...
14
votes
1answer
906 views

“ss” command in iproute package; why query slab table for timewait sockets?

Forgive me if this isn't the best forum for this question, but it seems more relevant to the kernel than to the programming itself. I'm writing a script that queries the system for open ports so that ...
19
votes
3answers
21k views

How can I communicate with a Unix domain socket via the shell on Debian Squeeze?

I’m running a Debian Squeeze web server. I’ve installed memcached on it, and configured memcached to listen on a Unix domain socket (at /tmp/memcached.sock), as it only needs to receive messages from ...
2
votes
1answer
170 views

Wrapping socket connections

I'd like to wrap an insecure connection (this one: http://culturedcode.com/things/) with a secure tunnel, a bit like http://en.wikipedia.org/wiki/Stunnel does, just using UNIX tools. What's the best ...
10
votes
5answers
7k views

Under AIX, how can I get the full path of a program bound to a port?

Under Linux I can use netstat -tulpnw and ps, like so: # netstat -tulpnw | grep :53 tcp 0 0 127.0.0.1:53 0.0.0.0:* LISTEN 1482/named udp ...
4
votes
2answers
7k views

rpc.statd running on system not using NFS

I have a Debian machine that gets warnings (via the Tiger automatic auditor) that rcp.statd is listening on such-and-such socket. Googling shows rpc.statd is a daemon used by NFS. As far as I know, ...
6
votes
1answer
3k views

How long is a TCP local socket address that has been bound unavailable after closing?

On Linux (my live servers are on RHEL 5.5 - the LXR links below are to the kernel version in that), man 7 ip says: A TCP local socket address that has been bound is unavailable for some time after ...
16
votes
2answers
3k views

What is a socket?

Could someone explain to me what a socket is? I see it in many acronyms in context of SSL, etc. Also, why is it called a socket? Is it purely because it was what a name they invented? Or was it the ...
22
votes
2answers
5k views

Who's got the other end of this unix socketpair?

I want to determine what process has the other end of a unix socket, that was created with socketpair(). I have a program parent which creates a socketpair(AF_UNIX, SOCK_STREAM, 0, fds), and fork()s. ...
9
votes
3answers
11k views

How do I reserve ports for my application?

How do I reserve a list of ports for my custom applications? To be specific, the product I'm creating has a lot of processes and a lot of intercommunication between them. The problem I'm having is ...
15
votes
2answers
7k views

/proc/PID/fd/X link number

In Linux, in /proc/PID/fd/X, the links for file descriptors that are pipes or sockets have a number, like: l-wx------ 1 user user 64 Mar 24 00:05 1 -> pipe:[6839] l-wx------ 1 user user 64 Mar 24 ...