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Questions tagged [netcat]

Netcat is a featured networking utility which reads and writes data across network connections, using the TCP/IP protocol.

features:

  • Outbound and inbound connections, TCP or UDP, to or from any ports.
  • Featured tunneling mode which allows also special tunneling such as UDP to TCP, with the possibility of specifying all network parameters (source port/interface, listening port/interface, and the remote host allowed to connect to the tunnel.
  • Built-in port-scanning capabilities, with randomizer.
  • Advanced usage options, such as buffered send-mode (one line every N seconds), and hexdump (to stderr or to a specified file) of trasmitted and received data.
  • Optional RFC854 telnet codes parser and responder.
186 questions
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Using netcat in windows to forward a tcp door to another machine

I have a computer with windows 7 under a firewall which can only initiate connections to other computers. It has a proxy server on it (port 9000) and I want to forward it to another machine (192.168.1.1) using netcat. Suggestions/ideas as to how to…
user59067
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How do I test HTTP Pipelinning?

I am trying to test if site/server/whatever has ability to pipeline HTTP request. So far, I think it is possible to send several request through one curl session, like: curl http://www.example.com/1.html http://www.example.com/main.css…
Ency
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"netcat -e" / "nc -e" on Mac OS X

netcat [...] -e program nc [...] -e program Is supposed to run program as a server (as far as its stdin and stdout are concerned). netcat on Mac OS X does not seem to have this -e option. Why is that and is there a way to enable it?
xyz
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Connection refused from localhost to localhost

I started a tcp listener using nc -l 127.0.0.1 900 and then attempted to connect to it using nc 127.0.0.1 900 when I got the connection refused error. The same happens when connecting using telnet. ufw is disabled. I don't understand how this could…
pathfinder
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Why am I only achieving 2.5Gbps over a 10Gbe direct connection between 2 machines?

I have 2 machines directly connected to each other with a 7 foot Cat6a ethernet cable (included in the box of the NIC cards). The PCIe x4 NIC I bought and in both machines is this: https://www.amazon.com/gp/product/B07CW2C2J1 I'm trying to debug why…
Mike
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Achieving very fast (300+MB/sec) file transfer on Linux

I'm working with high end hardware, however I'm hitting cpu bottlenecks in all situations when attempting to move large amounts of data. Specifically, I'm moving large virtual machine image (VHD) files of 2TB between two Ubuntu hosts. My latest…
epea
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SSH tunnel and reverse SSH tunnel at the same time on the same port

I have a computer A, a server B (Azure VM) and a second computer C. I want to connect from A to C through the server B. Setup: A: ssh -i location_of_private_key -L 12000:public_IP_of_B:20000 user@serverB C: ssh -i location_of_private_key -R…
Bonjour123
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netcat host not found when listening

i am trying to connect two hosts using netcat. i have downloaded netcat for windows, but when i run the command nc -L -vv -p 4444, it fails with the error nc: forward host lookup failed: h_errno 11001: HOST_NOT_FOUND! I have tried specifying ip…
inXperienced
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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 some text: aaaaaaaaaabbbbbbbbbbccccccccccc And…
user462378
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Why does tcpdump see a reply, but not netcat

I'm debugging a OpenVPN site-to-site connection using UDP in netcat. I can get packets to flow in one direction (host A->host B), but not the reverse one. root@hosta:~# nc 10.0.3.2 1234 -u root@hostb:~# nc -l 1234 -u The strange thing is that,…
user410784
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Check if iptables rules are working

I have three virtualboxs. 1) Virtual machine VM-A that works as a router with two interfaces: eth0 - 10.160.10.254 eth1 - 172.10.0.254 2) Virtual machine VM-B that works as an internal network with one interface: eth0 - 10.160.10.1 (and with gw to…
codin
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nc exits immediately, on connection, when run as an upstart job

I'm using the following /etc/init/jsonlog.conf upstart job: description "jsonlog" start on runlevel [23] stop on runlevel [06] respawn script cd /tmp echo "about to listen" /bin/nc -l 3333 echo "finished listening" end…
fadedbee
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tcp retransmit via curl and netcat

I'm trying to setup iptables to cause realistic network failures between docker containers. On the server, I run both netcat -lk 1234 and an Erlang cowboy server. On the client I run clients: echo blah | netcat myserver 1234 curl…
darnok
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netcat unable to connect to remote host

I've asked this on the DigitalOcean forum but haven't heard any responses. I have a droplet running Debian 8.1 x64 and I'm trying to set up a basic netcat connection (I'm using nc.openbsd on both my local and remote machine). I ssh into my server…
Ben Kushigian
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IP Forwarding Configurations

I am testing ip forwarding to recieve external connections from my computer at home. I did the following from my router settings: Turned off firewall of router and fedora, done forwarding settings, set netcat to listen to port 80 and checked…
corsel
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