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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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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1answer
246 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
261 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
835 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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1answer
2k 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
620 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
3k 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
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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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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
158 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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2answers
5k 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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2answers
1k 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 ...
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1answer
131 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 ...
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2answers
474 views

Nested Redirection in BASH

I have a scenario where I want to filter log files. To do this I am wanting to follow the last 10 lines or so of a log file and as new lines are read in, pipe them through an awk program and then ...
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2answers
633 views

Meaning of “netcat can be used as a backdoor” [closed]

I recently read about netcat and it is often mentioned that it could be used as a "backdoor". What exactly is meant by backdoor? Could some one give an example of such usage of netcat.
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1answer
651 views

How to pipe the output of a linux command back into the predecesssing command

The linux command nc -l 8090 | (read METHOD URI PROTOCOL ; echo "method: $METHOD" ; echo "path: $URI" ; echo "prot: $PROTOCOL") listens to port 8090 and when I type something like ...
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3answers
2k 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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1answer
834 views

Unix bidirectional pipe on commandline

I've been able to use this linux command to connect Netcat to a serial port: nc -l 80 <> /dev/ttyS0 I would like to be able to log this transaction. My backup plan is to use Wireshark to ...
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1answer
615 views

TCP connection to my host's public IP address using Linux netcat

I need to make a TCP connection to my machine through an application that needs only the public IP address and port to connect. I have been able to do it in Windows, but I need to do it in Linux ...
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1answer
6k 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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2answers
1k views

How do I send and receive simultaneously with netcat?

I need to test a TCP server by connecting with netcat as a client sending a stream from /dev/random and at the same time pipe the output to /dev/null. Receiving: nc 127.0.0.1 3000 > /dev/null ...
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How do I make netcat receive UDP packets from any host?

Is there a way to make netcat receive UDP packets from any ip:port? I don't want it to bind to a specific host as the first packet comes. I can consider alternatives, but they have to be bash ...
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1answer
1k views

netcat and tee redirection via a bash script

Quick question that has been haunting me all day.. I have a bash script that includes this line: nc -l 8044 | tee nc-output & The output from netcat is never being written to nc-output. If I ...
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1answer
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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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2answers
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How to get the WAN IP from a router using UPnP/SSDP

I'm trying to find a way to get my router to report back my WAN IP using UPnP/SSDP, but so far I have been unable to even get a list of UPnP supporting internet access devices on my network. Here's ...
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Port forwarding on D-link DIR-615 router

I'm attempting to configure my router to forward a port to my Linux machine. The Linux computer has a static IP (192.168.0.185) Right now I'm just experimenting to make sure I can forward a port, so ...
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1answer
1k views

Can I use nc and/or stunnel to make a transparent SSL proxy such that I can specify the outgoing source port?

I've been playing around a bit with different variations and can't seem to find something that quite works. I want to be able to 'bridge' an SSL connection across a particular gateway node in the ...
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2answers
571 views

How to set up a secure chat using netcat

I use netcat to chat in LAN. PC1 listen port 8080 $ nc -l -p 8080 PC2 connect to PC1:8080 $ nc 192.168.10.1 8080 Unfortunately, this is not secure. Anyone sniffing packets can intercept my ...
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1answer
729 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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1answer
3k views

bidirectional socat functionality with nc

This is question is somehow related to How is it called when listening(connecting) two sockets and exchanging data between them? In the test setup I have three terminal windows open I run in Term1: ...
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1answer
243 views

Can I use dd to clone two drives from two machines simultaneously?

To clarify, I have two machines: Machine1 and Machine2. Each machine has 2 disks (Machine1 has Disk1-1 and Disk1-2; simiarly, Machine2 has Disk2-1 and Disk2-2). Can I use 'dd' to clone Disk1-1 to ...
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4answers
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Can the telnet or netcat clients communicate over SSL?

I would like to test client connections with IMAP over SSL, HTTPS, and other secure text-based Internet protocols over SSL/TLS, the same way I would using telnet or netcat if they were not tunneled ...
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1answer
304 views

cat file that contains escaped characters to netcat

I'm trying to test a webserver with some HTTP request written in a file. GET / HTTP/1.1\r\n\r\n Right now I'm feeding that file to netcat like this: cat files | nc localhost 80 However, the \r\n ...
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1answer
199 views

Monitoring incoming requests on a web hosting server

I have a web hosting account with GoDaddy (its a Linux based hosting). Can I install applications like netcat to monitor all incoming requests to my website on a certain port? If not, is there any ...
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2answers
8k views

Netcat/socat behavior with piping and UDP?

I guess this is close to linux - Netcat stops listening for UDP traffic - Super User, but I thought I'd better ask anyways As far as versions of netcat I'm using Ubuntu 11.04 and the default netcat ...
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1answer
8k views

Linux built-in or open source program to join multicast group?

I'm using tcpdump to capture multicast packets and had to code up a custom program to join multicast feeds so tcpdump will "see" the packets. Just wondering if netcat or any other applications can ...
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3answers
1k views

Using nc (netcat) to emulate NTP server response

I want to test some security on an NTP client developed in-house and would like to use netcat to do it. I have packets captured with Wireshark from previous NTP exchanges that I tried to feed to the ...
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1answer
140 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
2k views

versions of netcat

I've tried the two main versions of netcat : GNU and BSD. (mine is BSD Version). On GNU version, the command $ nc -l -p 12345 works fine but with BSD, option -l (listen) can't be used in conjonction ...
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1answer
2k views

Differences in nc (netcat) options on Ubuntu vs RedHat

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 seconds is ...
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1answer
624 views

How to purge connections left open by SSH ProxyCommand?

I have a webserver WWW1 and a front-facing proxy PRX. I use SSH ProxyCommand to connect to WWW1's internal IP (private IP) via PRX (private+public IP). For some connections (not all) I see a network ...
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4answers
22k views

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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3answers
8k 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 ...
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1answer
4k views

Terminal command to send data (plain text string) to a port at a remote computer

I am trying to send data (plain text string) to a port at a remote computer using terminal utility. The string would be used to trigger something on the remote computer running a program that would ...
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1answer
498 views

Simple secured SFTP tunnel?

I'd like to setup an sftp tunnel so that I can connect to an IP-secured SFTP server through a gateway computer from anywhere, and download the files to anywhere. I was thinking of using a combination ...
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1answer
913 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 ...
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1answer
1k views

Netcat file transfer problem

I have two custom scripts I just wrote to facilitate transferring files between my VPS and my home server. They are both written in bash (short & sweet): To send: #!/bin/bash SENDFILE=$1 PORT=$2 ...
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2answers
1k views

nc or socat: How to read data from remote:/dev/ttyACM0?

I have a device running at a remote computer on /dev/ttyACM0 Now I want to read that data on my computer. I can connect to it over ssh. Unfortunately I am a nc/socat rookie and no howto covered this. ...
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1answer
24k views

Netcat on Mac OS X

Is anybody else not able to get nc -lp 8888 working on Mac OS X? Is there another way to get this to work?
9
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4answers
16k 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. ...