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

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If an I/O function cannot fail with EINTR, does that mean it never blocks? [migrated]

For example, consider fdopen. I have been wondering whether it's possible for this to block, if, say, the file descriptor argument refers to a pipe or socket. A Google search hasn't turned up anything ...
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0answers
25 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 ...
2
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0answers
19 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 ...
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1answer
39 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, ...
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1answer
43 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 ...
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784 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: ...
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1answer
459 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 ...
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1answer
13 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, ...
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1answer
208 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 ...
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0answers
61 views

Switching from LPD to SOCKET protocol in CUPS?

I have a USB+LAN printer that was USB-connected to a Windows computer and shared via LPD. In CUPS this was configured to be a raw printer. The jobs where processed correctly. I then simply put the ...
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1answer
43 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 ...
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1answer
77 views

ss is replacing netstat, how can I get it to list ports similarly to what I am used to?

I've been trying to modernise my way with Linux by, for one thing, ditching netstat for ss. I looked up my favourite command line flag for netstat in the ss man pages, and was very glad to find that ...
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1answer
279 views

Opening a socket in Kali Linux using bash scripts

I know how to open a TCP or UDP socket in Ubuntu, with the following command : exec 3<>/dev/tcp/google.com/80 for example: we can open a TCP socket on port 80, but in Kali Linux there's no ...
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0answers
76 views

linux + what are the messages bad tty under /var/log/messages file

under /var/log/messages I see the following messages "bad tty" what the meaning of these messages? second is it caused because some application that called - owstd ? as we can see from the log? ...
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0answers
23 views

Placing OpenSSH control socket in /run

OpenSSH has a feature that allows you to multiplex connections over a controlsocket. It is generally accepted that these control sockets should not reside in a common area, due to the security issues ...
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2answers
99 views

Runs perfectly through the command line, will not work through systemd ExecStart

I've installed Butterfly http terminal server, written in python, on my Arch machine. I'm new to systemd, but I'm having an issue with one of the command line parameters. /usr/bin/butterfly.server.py ...
2
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1answer
123 views

Connect through different interfaces to the same server (SO_BINDTODEVICE): Destination Host Unreachable

I have 2 interfaces: eth0 and wlan0, each one connected to a different router. Their network specs are these: eth0: ip: 192.168.1.7 Gateway: 192.168.1.1 Submask: 255.255.255.0 wlan0: ...
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0answers
87 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 ...
6
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1answer
245 views

How does moving a unix domain socket enable socat to monitor traffic?

socat can be used to monitor traffic across a Unix domain socket: sudo mv /path/to/sock /path/to/sock.original sudo socat -t100 -x -v UNIX-LISTEN:/path/to/sock,mode=777,reuseaddr,fork ...
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0answers
37 views

Which Privileges Should Assign For Create Raw Sockets

I want to run an ICMP command to ping an IP Adress at Java: InetAddress.getByAddress("XXX.XXX.XXX.XXX".getBytes()).isReachable(1000); However there is a security restriction that: Normal users are ...
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0answers
44 views

how to fix a port no statically for client request on client side?

I have an assignment to implement: unicast multicast broadcast in Java socket programming. While implementing the multicast part I decided to do it on my own system itself, so for the purpose of ...
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4answers
1k views

Are Unix Internet sockets files?

I understand that "Everything is a file" is one of the major concepts of Unix, but sockets use different APIs that are provided by the kernel (like socket, sendto, recv, etc.), not like normal file ...
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2answers
258 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; ...
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1answer
19 views

How to apply a parameter to packet so TC can prioritize\classify it

I want to add a parameter to the packet so that I can later let TC (HTB in specific) prioritize my packet (based on filtering that parameter). I thought about filtering by socket but as I understand ...
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1answer
187 views

Advantages of using named pipes and sockets rather than temporary files

I have two cooperating programs. One program just writes its output to a file and the other one then reads from the file and spits the data out for the front end to work with. I have been reading ...
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108 views

Stopping syslogd also closes /dev/log UNIX domain socket

I am working on a project and from some testing I found out that stopping syslogd daemon also closes /dev/log socket. Is there some other way so that even if syslogd is down, /dev/log socket still ...
2
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0answers
111 views

Emulate console by sending data on one UDP port, and receive text from another

Note: I also posted this question on SuperUser, because I'm not sure where it belongs I'm trying to establish a "console-like" connection with a National Instruments cRIO-FRC. It broadcasts its ...
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3answers
3k views

Why are TCP/IP sockets considered “open files”?

I need some assistance grasping what I'm sure is a fundamental concept in Linux: the limit for open files. Specifically, I'm confused on why open sockets can count towards the total number of "open ...
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1answer
121 views

ip forwarding to remotely connect to a socket listening to localhost only?

I must transfer data from PC1 to PC2 using a specific port, but the socket opened on PC2 only listens to local host. Is there a way to "trick" the socket into accepting the connection from PC1?
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3answers
115 views

Server running on guest Linux VM will not accept connections from Windows host

I have a simple echo server program running on CentOS 7. If I run both the client and the server in the VM, I can connect to the server. I'm using VirtualBox with the "bridged" network configuration. ...
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1answer
151 views

Archlinux ARM Apache server fails to start

I am currently setting up an Apache web server on my Pi running on Archlinux ARM. After installing and making the first small configurations I have tested it and it works. Then I stop the server and ...
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70 views

Why was n't kqueue socket polling mechanism not implemented in Linux?

Linux has epoll for socket polling mechanism. kqueue seems to be better than epoll. Why did linux went with epoll rather than kqueue? I read about libkqueue. But that is implemented in user space and ...
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0answers
202 views

X11 bad access at first try but working on successive tries

I use the following setup to forward X11 output from my local machine to the server. I will outline the setup: X11 server and the client are on the same local machine. The X11 server runs on my ...
0
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1answer
77 views

What are the differences between socket polling mechanisms of kqueue and epolling?

kqueue socket polling mechanism is used in FreeBSD and epolling in Linux. I would like to know what are the differences between the two mechanisms?
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3answers
277 views

nc not waiting for server disconnect on OS X

How to make nc client on OS X Mavericks keep socket open and read data until server disconnects the socket? I want to send data to a server through nc and then use the response. Problem is that nc ...
2
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1answer
76 views

Is there a system call to bind a file descriptor directly into another?

A read() & write() loop would probably be as good as what I'm looking for, but nevertheless is anything like that around or is it impossible because of an obstacle I didn't envisage ? I'm curious
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0answers
108 views

closing socket after forcing terminal close

I'm running Bluetooth socket server, this server is listening to incoming connection. but I forced the terminal close ctrl + Z . after that the server is not listeing any more and show me the output ...
3
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1answer
59 views

Can close() block?

For example, if you close a pipe or socket that still has data in its write buffer that hasn't been read by the process on the other end, does close() block until the data is read or the other process ...
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0answers
49 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 ...
2
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0answers
53 views

Last data traffic time for a TCP socket

Is it possible, to find out when was the last time there was any traffic on an opened TCP socket? Keepalive and timeout timers are based on this statistic, so I guess it has to be stored somewhere. ...
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2answers
7k views

How to make a TCP socket time out

For network catastrophe simulations of our server environment, we are looking for a way to intentionally timeout a TCP socket. Are there any simple ways for existing sockets? Also, little C test-case ...
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1answer
265 views

How can I allow applications to bind to any address in a subnet assigned to an interface?

I recently got a static IPv6 /56 prefix of my own from Freenet6, and am trying to allow applications to bind arbitrary addresses in the prefix. I modified the tunnel creation script that gogoc uses in ...
3
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1answer
1k 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
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2answers
10k views

ssh: Read from socket failed: Connection reset by peer

When I try to ssh to a remote host, I get the following error messages: root@cloudstack-server-1:~/.ssh# ssh ubuntu@172.17.4.17 -v OpenSSH_5.9p1 Debian-5ubuntu1.1, OpenSSL 1.0.1 14 Mar 2012 ...
3
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1answer
788 views

Memcache 'stats' reports non-zero 'curr_connections' - but lsof shows no socket connections

Our memcache daemon reports non-zero 'curr_connections'... $ telnet memcache-server 11211 Escape character is '^]'. stats ... STAT curr_connections 12 ... ...and yet, lsof shows no socket ...
8
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3answers
2k views

Is there a file for each socket?

"Everything is a file" in the UNIX World. Above sentence is famous. When I run echo "hello programmer" >> /dev/tty1 , I can watch the given string on TeleType 1 , .... What and where is file ...
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2answers
112 views

Detect open sockets manually (not using nc or similar)?

I'm trying to debug a network problem on a embedded system which has a very limited set of userspace applications. Meaning I can't use any of the following sudo lsof -i sudo netstat -lptu sudo ...
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2answers
174 views

How to see the amount of pending data on a unix domain socket?

When I'm logged to a tmux session from two different computers, I'd like to be able to trace the amount of pending data on the sockets of both tmux session. To test this I logged to computer A and to ...
3
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2answers
1k views

Socket connect to a ports bound to IP vs localhost

It is my understanding that sockets bound to ports using localhost will not be visible to the subnet because the binding is not with the nic IP address. Local processes connecting to such port will ...
2
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1answer
523 views

Using a Unix Domain Socket to Control VLC

I am interested in using a UNIX-Domain Socket to control VLC playback. This functionality is outlined in the VideoLan documentation for using oldrc. So what I need to is startup vlc with a command ...