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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138 views

Probing a port for RDP

I use an ssh tunnel to RDP into my home computer ("home"). Occasionally, the tunneling software running on home crashes and the RDP port stops getting tunneled. I've attempted to resolve this by ...
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162 views

Creating a proxy with netcat

I'm trying to setup a permanent proxy server for one of my servers to reroute connections having issues. The proxy server is running Centos 7 x86 User -UDP or TCP-> Proxy -> Server I am am ...
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1answer
873 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 ...
0
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1answer
249 views

automatically start netcat on localhost and remote-host and keep it active

I found this answer by @jeremytrimble on Stack Overflow which explains how you can read a FIFO file over network. I wonder if it’s possible to start these netcat commands automatically, e.g. in a ...
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1answer
57 views

Using netcat to connect to znc

I'm trying to send status updates to my IRC channel on irc.foo.com My limitations are.. The msg has to be sent to irc.foo.com from my ZNC account on znc.bar.com (znc is connected to irc.foo.com) ...
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1answer
158 views

Bash - Parsing XML output of nmap

I am trying to write a bash script that will take port id I retrieve from an nmap command, and then use those ports to send a file using netcat. So I got some basic knowledge using this link, How can ...
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4answers
22k views

Sending file via netcat

I'm using something like this to send file from one computer to another: To serve file (on computer A): cat something.zip | nc -l -p 1234 To receive file (on computer B): netcat server.ip.here. ...
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0answers
81 views

Give a command HTTP proxy auth access

I'd like to let a command (wsimport) access a URL through an HTTP proxy with authentication. It can be configured to use a proxy, but not with auth. I was wondering if a tool such as netcat, or any ...
15
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1answer
7k views

How can I force netcat to send my input immediately, not just on newlines?

How can I force netcat to send my input immediately, not just on newlines? I want to test an HTTP parser manually and check how it behaves when header lines are spread across multiple packets.
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0answers
137 views

SImple server to run program and return result

I am attempting to create a minimal local listen server that takes an input request, pipes the input to a program and then returns the result of the command. What I have at the moment is the program ...
0
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1answer
27 views

OS X LoginHook - nc exits prematurely for no apparent reason

I'm trying to use loginhook to download large amounts of data and I've been having problems which I've nailed down to nc exiting prematurely for no apparent reason. This is a simplified test script: #...
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2answers
674 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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3answers
3k views

Use netcat as a proxy to log traffic

I want to use netcat as a proxy to log http requests and responses to files, then tail these to inspect traffic. Think wireshark. Tried the following where 'fifo' is a named pipe, 'in' and 'out' are ...
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0answers
27 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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2answers
9k 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 ...
7
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1answer
465 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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1answer
3k 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
75 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 ...
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1answer
569 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. ...
4
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0answers
130 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
1k 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
9k 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
407 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 ...
3
votes
1answer
8k 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, ...
2
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1answer
764 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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1answer
643 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
4k 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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0answers
220 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
579 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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2answers
1k 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 ...
0
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1answer
62 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
326 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 ...
7
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3answers
11k views

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 ...
0
votes
1answer
400 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 ...
1
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1answer
707 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 ...
1
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1answer
564 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 ...
1
vote
1answer
101 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
193 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 ...
2
votes
3answers
575 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 ...
7
votes
1answer
13k views

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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2answers
2k 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
votes
1answer
362 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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2answers
1k 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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vote
2answers
735 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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0answers
4k views

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
1k 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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2answers
4k 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
315 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
1k views

Bash RTSP client with netcat - keep connection open while parsing sent data with sed?

I am trying to make a RTSP client in bash. Problem is that I must make only one connection to the server through which it will send video frames. I can keep it on one connection up to the point at ...
0
votes
1answer
146 views

Knock on a port to get service and version

I'm having difficulty remmebering a certain command I would use in bash that would give information about a port it would 'knock' on. I've used ssh backdoors before so that I can access my home ...