Netcat is a simple but powerful utility program that reads and writes data across network connections, using TCP or UDP protocol, IPv4 or IPv6, with a variety of functions.

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Unix : `nc` on Ubuntu vs Redhat (netcat)

nc -q -1 local host ${PORT} ${CMD} In Ubuntu, nc may be used as above, with the -q option. See manpage. -q after EOF on stdin, wait the specified number of seconds and then quit. If ...
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20 views

Netcat redirect remote console application

I have a windows interactive command line application ('pianobar', Pandora client) that I'm running on a Win2k8 server that I would like to control remotely, possibly using netcat. I need to be able ...
4
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1answer
3k views

Why is “nc -l xxxx” not opening a port?

I'm trying to get netcat to listen on port 4444, but it doesn't seem to be working. I am checking to see if the port is open using nmap, but it doesn't pick it up and I can't figure out why. I have ...
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0answers
7 views

Using DJB's tcpclient or tcpcat bidirectionally

Can someone post an example on how to use DJB's tcpclient bidirectionally? We need to read from Tor's ControlPort as well as write to Tor's ControlPort. A "file" that is open for both, reading and ...
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How to edit a text file over a network with netcat plus some $EDITOR

(no alternate suggestions like vim --servername, or vim over ssh, or "just use ssh", or nfs, sshfs please. Also I prefer to avoid more elaborate incarnations of netcat like ncat) I'd like to edit my ...
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2answers
2k views

Sending text file contents to server using netcat?

There is a daemon process listening on port 5144, which I cannot to modify. I want to use netcat to send the contents of a text file to the server, but this causes netcat to hang the terminal until I ...
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1answer
264 views

Multiple unix pipes not working

This first pipeline works fine (printing "c"): echo "a" | sed 's/a/b/' | sed 's/b/c/' This one does not do what I expect (nothing gets printed when I feed an "a" into my fifo ): mkfifo fifo; cat ...
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233 views

Netcat error: Can't grab 0.0.0.0:80 with bind

When I tried to listen on port 80 in Windows 7 with netcat, I get this error: C:\Users\sashoalm>echo "hello, world" | netcat.exe -l -p 80 Can't grab 0.0.0.0:80 with bind On the other hand, ...
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1answer
34 views

Quickest way to upload to a server?

I am looking for a way to upload a large file (1gb) to a server. So far I have used scp, nc and sftp. Initially I start with a nice upload speed of around 2 mbps, but this quickly slows down to around ...
0
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1answer
84 views

How to send message both to netcat and other script?

I'm trying to make some client-server interface. Think of it as one-on-one chat. What I want to achieve are two horizontal views. Bottom for my (server) input, top for client output and my input. ...
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4answers
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How can I pipe commands to a netcat that will stay alive?

echo command | netcat host port This results in the command being sent to the remote host and some data being read back. But after a few seconds, the connection closes. The -w parameter did not ...
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53 views

DNS tunneling through an SSH connection looses connectivity

In the article 'UDP traffic through SSH tunnel', it is described how to tunnel DNS trough a SSH tunnel: client# ssh -N -L 6667:localhost:6667 user@server server# mkfifo /tmp/fifo server# nc -k -l ...
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1answer
274 views

Unable to transmit stream through OpenVPN tunnel

We are trying to transmit a video-stream via netcat from a OpenVPN server to a client. The server is a Raspberry Pi with Pidora running on it. The client is a Notebook with Ubuntu 12.04 and has a ...
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2answers
6k views

Netcat stops listening for UDP traffic

I am using netcat on some Linux machines (see this other question), but seeing some unexpected behavior. Unlike the guide in the accepted answer, I am not using UDP tunneling to do DNS queries. I ...
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3answers
116 views

Quick way to scan for opened ports on local network according to a list

How can I quickly find out whether port 80 is open/listening on a server via a bash script? Normally on all workstations the daemon is running, but sometimes it fails. I use the following command to ...
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1answer
530 views

Listen to port continuously and dump data to file

I use this command to listen to port and dump data to file: while : ; do nc -l 0.0.0.0 10000 > log.txt & done First request works perfect, it's dumped in log.txt but after first request, ...
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1answer
202 views

Saving Live Video received through Netcat

I'm using the following command to stream a video which I receive through Netcat. nc -l -p 5001 | mplayer -fps 31 -cache 1024 - (On Windows CMD) This command opens the MPlayer and plays the live ...
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6answers
750 views

How can I verify that a 1TB file transferred correctly?

I frequently transfer VM images from hypervisors to an archive server for long term storage. I transfer using netcat since it is faster than scp, rsync, ect.. hypervisor$ cat foo.box | nc ...
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1answer
378 views

How to wait for a response on the inbound side of the socket using NC command under BusyBox?

I am having problems using the Netcat that comes with BusyBox 1.1.3 to make an HTTP request and then receive the response. The NC command seems to quit out as soon as it reaches the end of the request ...
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1answer
133 views

How to upload a file to windows through a netcat session

I have a netcat session and I want to upload a binary to the target windows machine. How can I do so? Is there a native "wget" in windows?
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1answer
125 views

Why is Udcast is many times faster than Netcat?

I use Netcat once in a while to copy files or disk images over the network. While it does the job I always felt like it was always on the slow sluggy side regardless of using ssh, no ssh, compression ...
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2answers
376 views

Why is the '-e' option missing from netcat-openbsd?

Why is the -e option missing from the netcat-openbsd package? There is a netcat-traditional package but it has many features from the OpenBSD package missing. I am running Linux Mint 16. Does anyone ...
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77 views

Create duplex TCP tunnel in Windows with netcat

I need to create a TCP tunnel in Windows, I tried by chaining netcat: ncat -l 3333 | ncat 192.168.0.110 4015 This creates a single direction tunnel, though, as only the first netcat's STDOUT ...
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1answer
138 views

Netcat: Should I use Ctrl+C to close the connection?

I've opened netcat, and I'm entering things from the keyboard. When I've finished and I want to close the connection, should I just hit "Ctrl+C"? I want the connection to be closed "normally", but I ...
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132 views

pipe a serial port to a command that blocks? </dev/ttyACM0 nc -l 1234

For practical purposes I have only one shot at testing this, so I wonder how will </dev/ttyACM0 nc -k -l 1234 work when no client is connected. Will the kernel buffer all the serial data, will the ...
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117 views

netcat command is not working in bidirectional mode

I am using netcat in Linux to send and receive data (using udp protocol) from a serial port to another device through the network. The command is : nc -u 192.168.10.12 < /dev/ttyUSB0 > ...
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2answers
433 views

Why can't nc / netcat sniff http port traffic easily?

I'm NOT looking for advice such as "try wireshark." I'm trying to understand what netcat is and isn't. When I try to listen (-l) to port 80, it says "address already in use." Can netcat not listen to ...
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1answer
49 views

Is it possible to set up my own DNS for my computer?

I don't know if I ask the right question but I hope this situation would give you the whole picture. I have my PC which located at my apartment. As usual, I get access to Internet using service ...
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0answers
96 views

nc connection refused even on loopback

I'm working on an embedded linux system, which appears to be networked correctly and is running ssh (dropbear) and rpcbind. I'm setting up a server application on it, and every single thing I try ...
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3answers
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netcat as a multithread server

I use netcat to run a simple server like this: while true; do nc -l -p 2468 -e ./my_exe; done This way, anyone is able to connect to my host on port 2468 and talk with "my_exe". Unfortunately, if ...
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1answer
138 views

Keep Process Running after Quitting NetCat

I am using NetCat on Windows 7 Professional to connect to my linux machine at home. I need to run a process and make it keep running after I close NetCat (Cmd Console). However when I close and then ...
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1answer
264 views

X11Forwarding using SSH and Netcat

From my machine, I must connect through nodes A, B, and C, to reach target: localhost -> A -> B -> C -> target Machine A is configured to refuse X11 Forwarding, so I guess I shouldn't ...
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2answers
300 views

netcat output into separate files using string delimiters

I want netcat to pipe the output of a tcp/ip connection to commands that examine the output and split it into distinct files separated by the strings "msg" and "/msg" from the output, something like ...
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1answer
66 views

DDNS and NetCat

I'm messing around with netcat(windows) and i'm trying to configure netcat listening to external connections.My ISP provides me dynamic IP so i gotta find a way to have netcat connecting back to me no ...
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1answer
135 views

Netcat connection over dynamic IP

I was playing around with netcat on my lan , had PC1 configured as a netcat client and PC2 configured as a netcat server into a reverse netcat TCP connection.This whole reverse TCP connection works ...
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3answers
198 views

Use xargs to send requests to the same server in parallel with netcat

I am trying to devise a one-liner to send text to a simple echo server - but multiple connections in parallel. This is what I'm trying: echo -e A,B,C,D | xargs -d, -i -P 4 echo {} | nc localhost ...
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1answer
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Can I pipe/redirect a console application through netcat so it can be used remotely?

Is it possible to 'pipe' an instance of a console application through netcat, so netcat is listening for a new connection and redirects the stdin and stdout over the network connection.
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696 views

How to send a binary message in TCP and store the response

I have to develop a client for a proprietary protocol and it would be very useful to be able to understand the behaviour of the existing server by sending it custom messages and look at the answer. ...
2
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1answer
160 views

ncat only works in certain scenarios

I tried using ncat (a “much-improved reimplementation of netcat”) to chat with a friend (and ultimately want to send a large file, but I know I can get that working once I get chat to work). We both ...
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1answer
151 views

Netcat stops when in a detached session

I want to use netcat to dump a number of blocks of strings to a file. I've been running this in my linux terminal and everything works very well until I try to detach my command line. If I run my ...
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2answers
197 views

Is it possible to push video out and usb over TCP/IP

I have a security camera system that is running Linux and is placed near the cameras (not in an office). It has a VGA out and uses a USB mouse. I'd love to redirect the VGA and USB to another ...
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2answers
418 views

List incoming connections on nc (netcat)

I set up nc on some computers in my office. They're connecting to our server like so: nc 192.168.1.2 3291 -e cmd Does anyone know how to list incoming connection attempts rather than accept one? ...
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0answers
868 views

Server: Microsoft-HTTPAPI/2.0 running on port 10234 on my Windows 7 pc?

I've recently set up a home server and spent some time working on the security. One of the tools I've been using nmap which I pointed at my Windows 7 desktop. It showed an unknown service on port ...
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2answers
460 views

ssh -R then expose the local port over HTTP?

Here's my scenario, I have two machines, A and B. A is behind a VPN, so B can't get to A. I have a web server: machine_a$ curl localhost:8088 "hello from machine_a" I have executed a remote SSH ...
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1answer
548 views

Can I stop a netcat tar pipe and continue later without overriding existing files?

I'm trying to copy a lot of files from my NAS to my server, about 2TB. I found that using a netcat tar pipe to copy the directories goes pretty fast, about 40mb/s. It seems to work faster than rsync ...
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how to bypass this error : “port range not valid”?

I have a port number that I want to connect to it via net-cat. previously I was working with windows and it was working perfect; but now in Ubuntu when I want to run the Net-Cat it's show me this ...
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3answers
715 views

How to make netcat support ssl by combining openssl?

Original netcat doesn't support ssl. ncat from nmap project does. In linux, we can connect multiple commands with pipeline. Is it possible to combine netcat and openssl to create a ncat?
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1k views

How to download a URL from internet by netcat?

I can use netcat to transfer files between two computers. # Server nc -l -p 8080 < file # client nc 192.168.1.101 8080 > file Can I use netcat to download a URL from Internet like wget?
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1answer
84 views

Two hop SSH with multiple user names

I am trying to set up an ssh proxycommand, where the user name at the final host is different from the user name at the original host. I am logged in on firstHost as username and want to effectively ...
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1answer
657 views

Cygwin netcat nc doesn't resolve hosts through /etc/hosts

I'm trying to use ssh to log into remote servers, and I have a ProxyCommand setup in ~/.ssh/config to use a proxy (setup through PuTTY to connect to a VPN). The ProxyCommand uses nc to connect ...