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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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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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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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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33 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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2answers
997 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
29 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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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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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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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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540 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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Can the Telnet/Netcat client 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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84 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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1answer
61 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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39 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
703 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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91 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
27 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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55 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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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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32 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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36 views

How to connect two debian VMs using vmware workstation so that one acts as a web server and the other as web client

I want to connect two virtual machines running using VMWare workstations - Debian Linux and I have setup private DNS server on one VM named "Server" and other VM is named "client". I am trying to ...
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1answer
4k 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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How to send OUTGOING to 1 netcat connection whilst reading INCOMING in a while loop?

I'm currently using netcat to grab the incoming lines of data with following: nc 192.168.1.1 1234 | while read line; do echo $line done I need to send outgoing data to the same connection, ...
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34 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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21 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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322 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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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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47 views

Port bridge with iptables

is there a way to achieve the same thing than bidirectional socat functionality with nc mkfifo backpipe nc localhost 42042 0<backpipe | nc localhost 1042 1>backpipe But only by using iptables ...
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Netcat doesn't detect open port with ngrok

I'm using ngrok 5002 to open up a port on my computer. I then do netcat -z xxx.xxx.xx.xxx 1-65000 with xxx.xxx.xx.xxx being my external ip I found via some web service. However, I expected ...
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91 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 ...
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1answer
5k 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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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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4k 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
352 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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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
55 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
299 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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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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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
624 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
7k 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
235 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
3k 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
478 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
903 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
138 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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335 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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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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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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261 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 ...