Questions tagged [netcat]
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.
210
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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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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?
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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. ...
50
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1
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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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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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What is the difference between telnet and netcat?
I am looking for an explanation where I can find the difference between telnet and netcat. In which cases should I use telnet and netcat? What a telnet can do that netcat can not do and vice versa?
I ...
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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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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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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 ...
21
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1
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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 ...
18
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3
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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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What is the Windows equivalent of the command "nc [server_name] [port]"?
On linux, one can connect to a server by typing
nc pwnable.kr 9000
on a terminal.
On windows, this does not work in Powershell nor cmd, and also Putty when using Telnet looks at first like it ...
17
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2
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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 ...
16
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3
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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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7
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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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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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How to send binary data in netcat to an already established connection?
I can do the following to send binary data in netcat:
echo -e '\x80' | nc host port
But I don't want to do it like this, what I want is to connect to a server:
nc 192.168.1.115 12345
And then send ...
13
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3
answers
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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 ...
12
votes
1
answer
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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, the ...
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1
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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
...
9
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3
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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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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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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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2
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Trouble with netcat over UDP
While troubleshooting the problem described here, I tried something really basic: I tried setting up a very basic netcat connection over UDP, and I noticed it's not working as I expect.
As with the ...
7
votes
1
answer
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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 ...
6
votes
1
answer
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How to make `nc` listen on a port without setting `SO_REUSEPORT`
I want to have a nc command listen on a TCP port so I did:
nc -lv 8888
Then in another console I checked if another program trying to listen on the same port would get an Address already in use type ...
6
votes
1
answer
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DNS tunneling through an SSH connection looses connectivity
In the Super User question UDP traffic through SSH tunnel, it describes how to tunnel DNS trough a SSH tunnel:
First, on the client side, do this:
ssh -N -L 6667:localhost:6667 user@server
Then, on ...
6
votes
1
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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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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 ...
5
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2
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Use rsync with nc as transport layer
By default, rsync uses ssh as a transport layer. Unfortunately with fast local network, ssh is very slow. Is it possible use rsync with netcat / nc ?
I have make some experiments, but it does not ...
4
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2
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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?
4
votes
2
answers
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Piping commands into nc
I've seemingly searched many very similar questions but never quite found something to work. I'm trying to use a raspberry pi (2nd gen) to communicate with a Wifi OBDII sensor. I'm able to use the ...
4
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1
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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 ...
4
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1
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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 ...
4
votes
1
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Install both gnu-netcat and openbsd-netcat simultaneously on Arch Linux
They are in conflict when I try to install them conveniently. How can I have both of them at the same time?
4
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1
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What's the alternative to "nc -l" for HTTPS?
You can run netcat in the "listen" mode:
nc -l 8080
This will listen on localhost:8080, dump everything that comes in to stdout and reply with data from netcat's stdin. This is useful for a ...
4
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2
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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 ...
4
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5
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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 ...
4
votes
1
answer
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UDP with netcat on Mac OS
I try to connect to a Tello drone from my Mac by opening an UDP connection to 192.168.10.1 via port 8889 to send commands and receive ack's from the device.
When using "Packet Sender" it works, but ...
4
votes
1
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How to get an ssh socks proxy on demand?
I know ssh provides a SOCKS proxy with -D. I wonder if it's possible to start such a proxy on demand, the moment a connection is made to a specified port (using the likes of socat and nc under the ...
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bidirectional socat functionality with nc
This is question is somehow related to
https://superuser.com/questions/270698/how-is-it-called-when-listeningconnecting-two-sockets-and-exchanging-data-betw
In the test setup I have three terminal ...
3
votes
3
answers
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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 ...
3
votes
1
answer
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Use netcat to listen on a port and send output from a command when a client connects
I have a Raspberry Pi (Debian Linux) connected to my LAN that can read data from some connected devices and output it to STDOUT.
Let's say the program is run on "Server" and I want to serve the ...
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2
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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 ...
3
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4
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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 ...
3
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1
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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 ...
3
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0
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Why does this netcat pipeline work in macOS but not Linux?
I set up the following pipeline. This allows me to see the raw HTTP requests and responses that pass through the pipeline.
Note: I use BSD nc below (this is what comes with macOS and AmazonLinux), ...
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2
answers
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Is NetCat command dangerous?
I'm s server-side developer and used to invoke the nc command to check whether a remote port is open.
Suddenly, the security guy prohibited the command and as soon as I use the nc command my ...
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3
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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?
2
votes
2
answers
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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? ...