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

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5 views

Socket timeout from an upstream DNS server nxfilter

We are using ubuntu 14.04 server and installed nxfilter latest version. After the run ./startup.sh script file, getting below error after the 2-3 minute and If i stop and start the again script then ...
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0answers
6 views

Udev rule setting up SocketCAN socket only works correctly only when run manually

I want to start slcand (the userspace daemon for the serial line CAN interface driver) when my Lawicel CanUSB dongle is plugged in. I followed Pascal Walter's step-by-step guide and all seems to work ...
2
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1answer
30 views

why do I find (under /proc/pid//fd) sockets with broken symlinks

I don't think they're closed, because I would expect that after a close() the fd would disappear, but I see a bunch of lingering fd -> socket[xxxxx] entries with broken symlinks which don't seem to be ...
2
votes
1answer
55 views

Blocking a specific external IP:Port connection in RedHat?

I know that in RedHat, in the IP tables I can block incoming connections to a local port. I can also block connections from a specific IP. But is it possible to block a connection from a specific IP ...
1
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0answers
14 views

Several TCP Window Scale values depending on interface?

Is it possible that TCP Window Scale value set by default on a socket (not raw) depends on the interface used? Where are these values stored?
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1answer
27 views

How do I get active unix domain sockets for a specific pid if I can't use lsof command?

If I have no permission to use lsof, how do I get them for a process with pid already known? Thanks I know netstat -l -p command print out active unix domain sockets, but it seems it's not updating ? ...
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1answer
67 views

How to pass received data from netcat to another script as argument?

I have simple bash nc script: #!/bin/bash nc -k -l 127.0.0.1 4444 > filename.out which listens 4444 port for TCP connection. Instead of redirecting received data to filename.out I would like, if ...
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0answers
19 views

Implications of increasing igmp_max_memberships

I am writing an application that will subscribe to 150+ multicast groups. It appears the linux default number of multicast subscriptions is 20 which can be increased via sysctl -w ...
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1answer
32 views

Where to put socket so PrivateTmp can be true

I have a C++ program which must communicate with other services (including httpd), and does so via a socket in /tmp With the advent of systemd and the PrivateTmp=true setting, processes like httpd ...
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0answers
87 views

Netlink access inside a network namespace

I'm trying set up an IPsec gateway (strongSwan) on a Raspberry Pi 2. The Pi was already providing a number of services on the LAN using a private IP address. My initial attempt to turn it into an ...
3
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0answers
83 views

Sharing unix sockets across unprivileged lxcontainers

I have two unprivileged containers and I'd like to share a unix socket between them. Each container has its own user on the host, complete with separate subuid and subguid mappings. I've tried ...
3
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0answers
13 views

Limit access/transmit rights on NIC to a single user application

I currently have a RT patched linux machine and I need to have full and undelayed access to my Wired interface card. I am running a realtime non-preemtable user application which sends a couple of ...
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62 views

espeak, alsa Unknown PCM

I have a Debian Wheezy and I connected to my linux a USB Dac. I use every time a MPD server (and that work) Now, I would like to use espeak with pyttsx But when I start my script (It worked and my ...
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0answers
27 views

How to decrypt data buffer in kernel level before read/recv [closed]

Before reading contents from socket file descriptor using read/recv(), can we preprocess/modify(e.g. decryption) data buffered in kernel level? I have server&client programs written in C, and I ...
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2answers
55 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 ...
2
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1answer
49 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 ...
1
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1answer
80 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 ...
11
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2answers
184 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 ...
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1answer
71 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
83 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
0answers
467 views

OEL6 Slow boot && Millions of socket files in /tmp/orbit-gdm

Background on question Lately I've been having some trouble with slow booting on the servers, sometimes over 2 hours to boot stuck on "Enabling Local Filesystem Quotas:" After searching I managed to ...
2
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0answers
45 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?
2
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1answer
86 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
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1answer
35 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 ...
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0answers
34 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
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1answer
30 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 ...
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1answer
233 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 ...
3
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0answers
64 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 by group, but only readable by others. I assume that the latter has no effect, as my understanding was that write access is needed to be able to work ...
2
votes
1answer
181 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 ...
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0answers
40 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
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1answer
42 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
105 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] ...
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0answers
58 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 ...
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0answers
50 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: == ...
3
votes
2answers
322 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
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1answer
60 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, ...
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2answers
249 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 ...
11
votes
1answer
552 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 Eduardo Fleury) that doesn't depend on the common PID file lock mechanism for daemons. There are ...
0
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1answer
100 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: ...
-1
votes
1answer
18 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
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1answer
382 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 ...
0
votes
1answer
132 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
850 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
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0answers
266 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
284 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
128 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
0answers
241 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 ...
3
votes
0answers
227 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
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1answer
78 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, ...
1
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1answer
207 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 ...