NETCAT EXAMPLES INSTALL NETCATWINDOWS VERSION

Netcat is designed to be a dependable вЂњback-endвЂќ device that can be used directly or easily driven by other programs and scripts. You wont be able to open a port lower.Netcat is a computer networking service for reading from and writing network connections using TCP or UDP. Lets assume we have 2 computers, 2.2.2.2 and 1.1.1.1 All of our examples will use these ips. The device the file will be sent to on the receiving device, run the command below, where the -l option tells Netcat to stay in listening mode waiting for inbound connections.Our Netcat Examples. In the following example, a file named linuxhint.txt will be transferred from a device to another. Netcat (nc) is also useful to transfer files between devices.

More technically speaking, netcat can act as a socket server or client and interact with other programs at the same time sending and receiving data through the network. It reads and writes data across the network from the command line, and uses Transmission Control Protocol (TCP), User Datagram Protocol (UDP), Stream Control Transmission Protocol (SCTP) or Unix sockets for communication.So basically netcat is a tool to do some bidirectional network communication over the TCP/UDP protocols. Ncat is a reliable back-end tool that provides network connectivity to other applications and users.

It can be used to create TCP/IP.In this tutorial, I am sharing a few useful netcat examples, although the sky is the limit when it comes to possible netcat use cases. Netcat or nc is a toolkit for debugging and checking network under Linux. This can be understood only by using and playing with it.8 practical Linux netcat command examples.

Netcat will try connecting to every port between 20 and 30.My preferred version is ncat. A scanning example from Hobbit is nc -v -w 2 -z target 20-30. On ubuntu there are 3 packages called netcat-openbsd, netcat-traditional and ncat.Port scanning with Netcat.

Netcat Examples Install NetcatWindows Version

Nmap also comes with a netcat implementation called ncat. Download and install netcatWindows version of netcat can be downloaded fromSimply download and extract the files somewhere suitable.Ubuntu syntaptic package has netcat-openbsd and netcat-traditional packages available. Ncat will not only work with IPv4 and IPv6 but provides the user with a virtually limitless number of potential uses. It uses both TCP and UDP for communication and is designed to be a reliable back-end tool to instantly provide network connectivity to other applications and users. Ncat was written for the Nmap Project as a much-improved reimplementation of the venerable Netcat.

Now from another terminal try to connect to port 1234 using telnet command as follows : $ telnet localhost 1234After connecting we send some test message like abc and ting tong to the netcat socket server. The -v option gives verbose output for better understanding. $ nc -l -v 1234The above command means : Netcat listen to TCP port 1234. Simple socket serverTo open a simple socket server type in the following command.

So this technique can be used for chatting between 2 machines.Ncat with the -c option can be used to start a echo server. Type something in netcat terminal and it will show up in telnet terminal as well. $ nc -l -v 5555Connection from 127.0.0.1 port 5555 acceptedThis is a complete Chatting System.

Here is a quick example.One machine A вЂ“ Send File $ cat happy.txt | ncat -v -l -p 5555In the above command, the cat command reads and outputs the content of happy.txt. File transferA whole file can be transferred with netcat. To start a netcat server using udp ports use the -u option $ nc -v -ul 7000Connect to this server using netcat from another terminal $ nc localhost -u 7000Now both terminals can chat with each other. $ nc -l -v 1234 > data.txtNetcat works with udp ports as well. Remember to always use the -v option for verbose output.Note : Netcat can be told to save the data to a file instead of echoing it to the terminal. It will be send back with вЂњвЂќ prefixed.The netcat-openbsd version does not have the -c option.

$ ncat -v -l -p 7777 -e /bin/bashThe above will start a server on port 7777 and will pass all incoming input to bash command and the results will be send back. Remote Shell/BackdoorNcat can be used to start a basic shell on a remote system on a port without the need of ssh. $ nc -v -n -z -w 1 192.168.1.2 75-85Nc: connect to 192.168.1.2 port 75 (tcp) failed: Connection refusedNc: connect to 192.168.1.2 port 76 (tcp) failed: Connection refusedNc: connect to 192.168.1.2 port 77 (tcp) failed: Connection refusedNc: connect to 192.168.1.2 port 78 (tcp) failed: Connection refusedNc: connect to 192.168.1.2 port 79 (tcp) failed: Connection refusedConnection to 192.168.1.2 80 port succeeded!Nc: connect to 192.168.1.2 port 81 (tcp) failed: Connection refusedNc: connect to 192.168.1.2 port 82 (tcp) failed: Connection refusedNc: connect to 192.168.1.2 port 83 (tcp) failed: Connection refusedNc: connect to 192.168.1.2 port 84 (tcp) failed: Connection refusedNc: connect to 192.168.1.2 port 85 (tcp) failed: Connection refusedThe вЂњ-nвЂќ parameter here prevents DNS lookup, вЂњ-zвЂќ makes nc not receive any data from the server, and вЂњ-w 1вЂќ makes the connection timeout after 1 second of inactivity. However this is not a proper use of netcat and a more applicable tool like nmap should be used. Port scanningNetcat can also be used for port scanning. After that its over.And after the first client closes down connection, netcat server will also close down the connection.

Reverse ShellsThis is the most powerful feature of netcat for which it is most used by hackers. C: ools c>nc -v -l -n -p 8888 -e cmd.exeConnect to from (UNKNOWN) 1182Now another console can connect using the telnet commandAlthough netcat though can be used to setup remote shells, is not useful to get an interactive shell on a remote system because in most cases netcat would not be installed on a remote system.The most effective method to get a shell on a remote machine using netcat is by creating reverse shells. The syntax of the command is same. So netcat can be used to convert any process into a server.Connect to this bash shell using nc from another terminal $ nc localhost 7777Now try executing any command like help , ls , pwd etc.On windows machine the cmd.exe (dos prompt program) is used to start a similar shell using netcat.

However a hacker is interested in getting a command shell. Your system runs (# telnet server port_number) => ServerNow using the above technique you can connect to say port 80 of the server to fetch a webpage. In ordinate telnet connection the client connects to the server to start a communication channel.