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

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-1
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2answers
20 views

shell command wrapper for socat

I have used the command socat - foo The text I type is sent directly to address foo. Is there some general-purpose wrapper for stdin (along the lines of ! from ed) that lets one parse a shell ...
-1
votes
0answers
11 views

connected device port number [closed]

I am using a NanoStation Device for send and receive some data by socket Programming I want to know ip address and port number to communicate I have ip address . how can i find the device's port ...
2
votes
1answer
25 views

When is a port considered being used?

I am getting port in use cannot bind on process restarts. I am trying to find out when a port is considered being used? Is it only when in LISTEN mode? Can it also be if a connection is open to the ...
0
votes
0answers
17 views

Why select do not tell me that a client wants to connect? [migrated]

I've made a simple tcp server that I can test with telnet program. When running it on windows, it works as expected, when running it on linux, the behavior is strange: telnet clients understand ...
1
vote
1answer
24 views

Socket remains ESTABLISHED even if remote process is stopped

I am running a celery - rabbitmq configuration between a client and a server. The client process opens a connection on the server at port 5672. Using netstat -np on the server I confirm that since the ...
10
votes
2answers
129 views

What is the difference between &6 and /dev/fd/6?

To read from file descriptor 6 I can use <&6 or </dev/fd/6 (aka /proc/self/fd/6). Usually both work equally well. However if that file descriptor happens to be a socket, strange things ...
1
vote
1answer
41 views

How to provoke a broken pipe

I try to debug a python script that interfaces MPD using python-mpd2. When the script tries to perform an action after being idle for a couple of hours, it terminates with an exception ...
3
votes
1answer
51 views

root cannot connect to symlinked socket of other user

I use oh-my-zsh's ssh-agent plugin to have a static symlink to my current SSH_AUTH_SOCK created. When connecting through SSH with agent forwarding enabled the file /tmp/ssh-agent-$USER-screen is ...
4
votes
2answers
3k views

How to send data from serial port over wifi?

I have microcontroller device which reads data from sensors and sends it via Serial to USB converter (ftdi232 cable). This Serial to USB converter is connected to ARMv7 mini-computer - CuBox with ...
2
votes
0answers
28 views

how to list all the epoll requests in linux

I used to use netstat for displaying all listening sockets. How can we list epoll requests on the sockets? Or is there anyway to dislay epoll requests using netstat?
1
vote
2answers
4k views

Installing vsftpd - 500 OOPS: could not bind listening IPv4 socket?

I have to set up a FTP server on my machine. I have installed vsftpd using the command: sudo apt-get install vsftpd I then edited the configuration file vsftpd.conf in the location /etc. The file ...
1
vote
1answer
190 views

/private/var socket not created with postfix/dovecot sasl

I'm currently running into a problem I have with my email server. I try to setup Postfix and Dovecot with SASL authentication but I get the following error when I connect with telnet (port 25) to the ...
29
votes
6answers
8k views

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

I want to determine which process has the other end of a UNIX socket. Specifically, I'm asking about one that was created with socketpair(), though the problem is the same for any UNIX socket. I ...
2
votes
1answer
57 views

Time synchronization, use NTP or just socket?

I am using a PC and a raspberry pi(both run Linux) to gather sensor data, raspberry pi gathers laser scan data, PC gathers image captured by camera. I must synchronize time for these two machines. I ...
0
votes
1answer
27 views

strace vs web browser

I was trying to strace an iceweasel like this: strace -e trace=connect iceweasel And I was expecting to see calls to connect when I load new pages. Surprisingly, there weren't any. Why so? Am I ...
0
votes
0answers
22 views

Connection refused, but only on one specific port

I have two service daemons. One responds; the other does not. The command netstat -pln returns, among others, Proto Recv-Q Send-Q Local Address Foreign Address State ...
0
votes
1answer
26 views

Server port doenst go back to listen and is in closed_wait state , because of starting an daemon application from client

Below is the basic client and server code . While iam trying to start an appliaction(which has to keep running in the machine once we send a msg to server) during connect call. using ...
1
vote
1answer
89 views

How to get more info about socket file?

For a socket file likes this: # ls -alti socket 14112 srw------- 1 root root 0 Nov 15 20:03 socket # cat socket cat: socket: No such device or address Since cat command is useless here, is there ...
11
votes
4answers
10k 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 ...
2
votes
0answers
33 views

Read but not write access to a socket on Linux, what can one do with that?

On a server installation, i found sockets writable to group, but only readable to others. I assume that the latter is withouth any effect, as my understanding was that write access is needed to be ...
1
vote
1answer
70 views

Differences between Unix Domain Sockets and Network Sockets?

Am I right that When two processes communicate by network sockets, each process create a socket (each socket belongs to one process), and the processes communicate by their sockets. When two ...
0
votes
0answers
28 views

What kinds of IPC are used in ssh port forwarding?

SSH local forwarding is specified by: -L [bind_address:]port:host:hostport on the local host, a process called P1 attaches to port, so that P1 and the ssh client SC can communicate. What type of ...
0
votes
1answer
33 views

What's the relationship between SOCKS and socket?

SOCKS (socket secure) is a protocol for proxy. A socket is an endpoint of communication. Why is SOCKS named after socket? How are they related?
2
votes
1answer
71 views

How do I find out more about socket files in /proc/fd?

Looking in /proc/$mypid/fd/, I see these files lrwx------ 1 cm_user cm_user 64 Oct 14 03:21 0 -> /dev/pts/36 (deleted) lrwx------ 1 cm_user cm_user 64 Oct 14 03:21 3 -> socket:[1424055856] ...
1
vote
1answer
157 views

Is it possible to establish a Socket session (between Server and Client) using shell commands ?

From what I read (only the very outline, i do not know C Language) a Socket session is established between a server and a client by calling functions for both of them in a certain order. It starts ...
0
votes
0answers
35 views

How to view source service(Process Name), when connection is established

Imagine there are 3 servers server1 has Haproxy, server2 has apache and server3 has MySQL. Deployed an application in server2. Client can send the request via Haproxy to server2. Apache listens on the ...
12
votes
3answers
19k 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 ...
3
votes
0answers
180 views

Scripted write-then-read from Unix domain socket using socat

I have a simple server listening on a Unix domain socket (on a CentOS box in case that's important). When I send the command "DATE" to the socket it writes back a welcome message and then "APRIL 15 ...
1
vote
0answers
43 views

What does the “ss -s” result “Total:” value represent? How to get details on each of them?

I am trying to understand what the ss -s result line Total: value represents, along with how this number is related to the other numbers. Note, the following values are equivalent: ss -s Total: == ...
11
votes
1answer
342 views

Does Linux automatically clean up abstract domain sockets?

There's a great answer on StackOverflow about providing a better lock for daemons (synthesized from here) that doesn't depend on the common PID file lock mechanism for daemons. There are lots of good ...
3
votes
2answers
225 views

Distinguish TCP server from client within netstat output

I have a socket connection between a client process and a server process, both running on my machine. There are two entries shown for the connection as, sudo netstat -ntp | grep 56442 tcp 1 ...
0
votes
1answer
49 views

Is the return value “-1” of the function socket close() method possible?

Under which circumstances is it possible to produce a return value of -1 when closing a network socket using it's close(int fildesc) method? I suppose it is possible with an invalid fildesc number, ...
-1
votes
2answers
204 views

Free or cheap shell (i.e., platform) to run a Linux C program with root privileges (raw socket)

I'm working on a Linux C program that needs root privileges (raw socket). I would like to run it on a host located in the US (I am in EU) to compare results. Is there any free (or cheap) shell ...
0
votes
1answer
116 views

A script to identify whether a file descriptor has gone bad

Problem : I have a server program running which connects to a remote program using TCP sockets. There many of them (say 20). My problem is one of the socket descriptor has gone bad and has recieved ...
0
votes
1answer
68 views

Path to unix socket

I'm using p0f to fingerprint network OSs from traffic captures. p0f has a feature allowing it to be set up as a daemon and listen in the background for a connection from a p0f-client (ie: ...
0
votes
1answer
205 views

Finding out the number of dropped packets in raw sockets

I am developing a program that sniffs network packets using a raw socket (AF_PACKET, SOCK_RAW) and processes them in some way. I am not sure whether my program runs fast enough and succeeds to ...
-1
votes
1answer
17 views

Need to write an automated web navigator with “click” and “retrieve” capabilities

In our company, several clients provide the detailed information information that we need in a web site. The amount of time that our employees spend navigating the remote website is simply ridiculous, ...
0
votes
1answer
106 views

Who opened a file descriptor? (socket)

I am using strace to track a program. In this line: recvfrom(7, "\0\260R\0\0\1\364\6\215\r\257\330\210\341\0\270\240\0\260R\0\0\0\0\0\0\0\0\0\0\0\0"..., 3000, 0, {sa_family=AF_PACKET, proto=0x88e1, ...
6
votes
2answers
399 views

What does an @ symbol denotes in the beginning of a unix domain socket path in Linux?

When I run netstat --protocol unix or lsof -U I see that some unix socket paths are prepended with @ symbol, for example, @/tmp/dbus-qj8V39Yrpa. Then when I run ls -l /tmp I don't see file named ...
1
vote
0answers
164 views

How to know file name of sockets or pipes in /proc/[pid]/fd

In Android, #ls -l 15843/fd gives following output, lrwx------ u0_a179 u0_a179 2015-05-28 11:58 90 -> socket:[193728] lrwx------ u0_a179 u0_a179 2015-05-28 11:58 91 -> ...
0
votes
1answer
217 views

Forwarding a udp socket connection to a range of ip addresses

I have a program which is a udp socket client. I can determine an IP adress to which this program should send. Unfortunately, I configured the computer as Access Point and don't know the address of ...
2
votes
1answer
89 views

using a pty like a socket?

I'm writing a collection of scripts to talk to an external program. My problem is that the scripts are only "alive" for a short time (triggered by a keypress in a larger program) but the external ...
2
votes
3answers
856 views

Nginx leaves old socket

I'm running Nginx 1.6.2 (the nginx-full package from the nginx/stable PPA). I'm using the unmodified configuration /etc/nginx/nginx.conf: user www-data; worker_processes 4; pid /run/nginx.pid; ...
2
votes
0answers
195 views

What does an inode for a socket contain?

I read somewhere that the inode for a TCP socket would contain the buffer space. Is that true, and if so, does it mean that the inode contains a memory address for the buffer space used by the ...
1
vote
1answer
72 views

how do applications communicate via sockets

On my computer audio works sometimes and sometimes not. I want to troubleshoot this. First I verified I am using pulseaudio. I did this by strace'ing the pulseaudio process: [pid 2289] send(28, ...
20
votes
5answers
7k 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 ...
12
votes
0answers
785 views

What is the purpose of sockets in layman terms? [duplicate]

I met several times the term "socket", so I looked it up on different sites, but each of them required too much knowledge in order to understand the explanation. What I read were things like: ...
3
votes
1answer
470 views

cannot start chrome browser - bind failed: Permission denied

I am using grsecurity kernel with CONFIG_GRKERNSEC_SOCKET_SERVER enabled: [*] Socket restrictions [ ] Deny any sockets to group (NEW) [ ] Deny client sockets to group (NEW) [*] Deny ...
1
vote
1answer
21 views

What setsockopts() 'name' values are used by the running Linux kernel?

I am introducing some new socket commands with nf_register_sockopt(&my_new_socket_options). How can I find, what setsockopt commands are already used (registered?) by the currently running kernel, ...
2
votes
1answer
337 views

How to report receive queue size for AF_UNIX sockets

netstat -a reports Recv-Q (amount of unread data pending for a reading application) for AF_INET sockets, but not AF_UNIX sockets (at least not for SOCK_DGRAM). Does anybody know a way to obtain this ...