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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Using netcat to log traffic to a file

I currently have a Windows 10 laptop connected to a Ubuntu 12.04 Laptop via Ethernet. All of the traffic from the windows system has been routed to go through the Linux laptop and out the Linux ...
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68 views

Listen to TCP port but only accept connections from a specified IP in netcat

I can use the following command in netcat to listen to a TCP port: nc -l -p 12345 But any IP can connect to this port: Is there a way to only accept connections from a specified IP? Note that I ...
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23 views

Use netcat to bridge thru firewall?

I have a machine behind a firewall. It's my machine, I have set up ssh, but it's completely firewalled. My solution has been to use a reverse shell set up on a cron basis to reconnect if it fails ...
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25 views

How to connect a vm to pc wth nc

I'm using a PC with Ubuntu Desktop and a VM (Virtual Box) with Ubuntu Server. I would connect my ubuntu desktop to VM with NC. How to I've setup my VM? My setting network of VM has bridge and with ...
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57 views

Setting up a SSL server that disconnects connections and executes commands

I am looking for suggestions on how to setup a simple SSL server that listens on a port and when a device connects, tell the device to disconnect, and then executes a command Context: The device is ...
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5 views

How would I do a GET and parameters requests in ncat using udp?

I'm trying to learn the difference between http and udp. So how would I request via udp: udp://server/path_name?param1=value1&param2=value2 Theoretically is that kind of thing possible or am I ...
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35 views

Port forwarding check on Comcast Router with netcat not working

I am very new to networking stuff, and I can't figure out why my port forwarding setup on my router is not working. Here is what I am using: Router: Standard provided by Comcast (I think it's Xfinity ...
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31 views

Save HTTP body with netcat

I can save the whole HTTP response from a server using netcat > output.txt, however this saves the HTTP response headers as well, if the body is text this isn't a problem as I can just ignore the ...
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31 views

netcat, nc, listen to several requests

I am trying to debug a network client. I just need to see several HTTP requests made in sequence. my first idea was o run nc -l 80, but it will keep open the socket after the first connection. Is ...
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87 views

Tracking Bandwidth & Latency in Linux [closed]

I'm trying to write a simple script that can detect dips in network traffic (both bandwidth and latency in both directions) between 2 arbitrary hosts in my network over time. Is there a tool to do ...
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42 views

netcat shell bind with mac (command -e not found)

I can successfuly use the command nc 192.168.. 5442 to connect to a listening device. The device listen using the: nc -lvp 5442. Everything works, I can send messages and receive some. I wanted to ...
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74 views

Using netcat for a Minecraft server

I have started learning the cmd code. While I was learning I have discovered netcat and that with it, you can make servers. I tried making a server for Minecraft likes this but it didn't work. Here ...
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456 views

netcat - keep listening for connection in Debian

There's -k option in OS X (BSD) version of netcat to keep listening after current connection is completed. However in Debian (GNU?) version this option is missing. There's -q -1 option to listen ...
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41 views

Reboot Linux via netcat?

Put aside the security risks, I need a temporary way to reboot over a network without relying on SSH. My SSH server has some other issues that I need more time to resolve those so need a way to bypass ...
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2answers
36 views

How can I make a one-shot sshd process?

I'm trying to find some invocation of sshd (OpenSSH on Ubuntu) that accepts only one connection, and then terminates the sshd process when that one connection closes. I see nothing in the sshd docs ...
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46 views

How can I process traffic between 2 instances of NetCat?

I have an utility that make some data transformation between stdin and stdout in both directions (encode / decode), and I want to make a some kind of bi-directional proxy using two nc instances and ...
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28 views

Does NetCat Read all Incoming Connections?

Imagine I have a server. If I set up a JavaScript to use the HTTP POST, would I receive that data using a NetCat command listening on port 8000 (the default POST port, I think)? Or does NetCat only ...
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258 views

Network transfer speed very slow using nc (netcat) over Wi-fi LAN

Anybody could have a hint why my home Wi-fi transfer using nc is so slow? What I've got: 1) Xubuntu machine with Atheros: $ lspci | grep -i wireless 03:00.0 Network controller: Qualcomm Atheros ...
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58 views

writing the response of netcat to the text file

I have a script file which sends soap request to the remote server and it gives the response in the terminal . However I want this response from terminal to the text file so I can use it later. I ...
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14 views

how to redirect incomming connections in one interface to another?

trying to do a quick test of one service that is listening on one interface, let's say 10.0.0.1:123 and i want a device that can only reach that host on another interface, let's say 192.168.1.1, to ...
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36 views

Tried to NAT hole punch the router in a loop, why didn't it work?

Comments on this answer indicate, that the NAT is not consulted if the destination is in the same network. But what if the destination is the public IP of the router, not 192.168.x.x or similar? I ...
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191 views

How netcat can`t receive UDP packets?

I have a simple UDP device (ENC28J60 ) connected to my computer with a direct cable. The device configured to send UDP packet to 192.168.133.1 IP, 6661 port. The computer ,Fedora 22 OS, interface ...
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426 views

Installing nmap and keeping it undetectable

I have a administrative computer fully equipped with antivirus (avg,norton,malbytes. etc) that I want to install ncat(nmap) on and keep it as close to undetectable as possible. How would I do this?
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696 views

Netcat connection closes after connecting through python

So I have installed Netcat on my raspberry pi and my mac and I can get them to connect really easily. Problem is that if I want a python script on my mac to establish the connection when the raspberry ...
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How do I interactively type \r\n-terminated query in netcat?

$ nc example.com 80 GET / HTTP/1.1 Host: example.com HTTP/1.1 200 OK ... It works, line separator is just 0A here instead of required 0D0A. How do I type a 0D0A-separated query in netcat? It is ...
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62 views

How to store data from different netcat connections in separate files?

I need a server that should receive data streams, store them in files and send further. Each connection should create a file with corresponding timestamp in file name, then write to it. My solution: ...
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116 views

nc and named pipes for port forwarding

I have my environment setup to listen to jetty on port 8888. However, for a limited time, I will have to also listen on 8889. I though of using named pipes and nc for that: mkinfo pipe1 /bin/nc -l ...
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265 views

How do I make netcat timeout nonsilently?

I'm trying to send some data to a server with a command like nc -w 3 IP_ADDRESS PORT < data where nc is the netcat from FreeBSD 5.4. When the server doesn't respond within 3 seconds I get no ...
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128 views

How to netcat all the files in my directory?

I have a directory of files I'd like to netcat to another machine. For one, I use nc <ip> <port> < sample.fls But if I have a directory of sample1.fls sample2.fls sample3.fls ...
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73 views

netcat between mac and linux only working in one direction

I have two machines on the same local network. One is a Mac (192.168.42.74) and one is a Dell (192.168.42.75) running Kubuntu Linux. If I issue 'nc -l 12345' on the Mac and issue 'echo "blah" | nc ...
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228 views

How to keep the reverse shell open in Netcat?

As soon as the command prompt is closed on the target machine the reverse shell is closed on the client machine. Is there any way to keep the port open and Netcat working after the target machine ...
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345 views

how to make a batch file close automatically

I have a .bat file which its content is like this: @echo off nc x.x.x.x 23 < commands.txt exit in which nc is a .exe file in the same directory nc.exe known as NetCat. The commands.txt file ...
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137 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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161 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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248 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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157 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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80 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 ...
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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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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 ...
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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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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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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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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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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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566 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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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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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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405 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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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, ...
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763 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 ...