#Bash netcat example manual

With the following command the remote system starts listening port number 3333 and write all incoming data into the myfile.Scanning ports is one of the most common uses for Netcat. As there is two parts the remote system should listed a port in order to accept data from the local host. Simply the provided file is transferred into the remote host like a simple binary copy and paste. echo 'HELO' | nc 192.168.10.10 25 Send File To Remote HostР”Р„nother useful feature of the netcat tool is the ability to send file into the remote system via network. In the following example we will send the data or message РІР‚СљHELOРІР‚Сњ to the remote port number 25 which is SMTP port by default. Also some text can be send to the remote system specified port. nc -z -u -v 192.168.253.134 100-200 Send Data/Text To Remote HostР”Р„s a simple tool netcat can be used for simple operations like sending some data to the remote system. In the following example we will scan the 192.168.253.134 for UDP port range 100-200. Other options are the same with the TCP scan where the hostname and port range is provided. In order to scan UDP ports the -u option is provided to the nc command. Connection to 192.168.253.134 22 port succeeded!Р”В¬onnection to 192.168.253.134 80 port succeeded! Scan UDP PortsР”В®ven not popular as TCP the netcat can be used to scan UDP ports similar fashion to the TCP scan. Only open ports are listed like below as we can see there is only 2 ports which are open. We will filter only lines those contains РІР‚СљsucceededРІР‚Сњ which means port is open. Only open ports can be listed by using the grep command. We can make output more readable by only printing the opne ports. Nc: connect to 192.168.253.134 port 87 (tcp) failed: Connection refusedР”В«y default the netcat tool prints all port results wheter they are open or closed. Nc: connect to 192.168.253.134 port 86 (tcp) failed: Connection refused Nc: connect to 192.168.253.134 port 85 (tcp) failed: Connection refused

Nc: connect to 192.168.253.134 port 84 (tcp) failed: Connection refused Nc: connect to 192.168.253.134 port 83 (tcp) failed: Connection refused Nc: connect to 192.168.253.134 port 82 (tcp) failed: Connection refused

Nc: connect to 192.168.253.134 port 81 (tcp) failed: Connection refused Nc: connect to 192.168.253.134 port 78 (tcp) failed: Connection refused Nc: connect to 192.168.253.134 port 77 (tcp) failed: Connection refused

Nc: connect to 192.168.253.134 port 76 (tcp) failed: Connection refused Nc: connect to 192.168.253.134 port 75 (tcp) failed: Connection refused Nc: connect to 192.168.253.134 port 74 (tcp) failed: Connection refused Nc: connect to 192.168.253.134 port 73 (tcp) failed: Connection refused PORT is used to specify the local or remote port.HOST is used to specify the IP address.OPTIONS is used to provide different options.As a network based tool it is mainly used with host and port information. The netcat tool or nc command has very simple syntax.

#Bash netcat example manual

The manual page provides more detailed information and description about the nc command. Port numbers can be individual or ranges: lo-hi Р”Р„lternatively the Linux and BSD systems provides the manual page of the netcat tool with the following command. X proto Proxy protocol: '4', '5' (SOCKS) or 'connect' w timeout Timeout for connects and final net reads W recvlimit Terminate after receiving a number of packets V rtable Specify alternate routing table q secs quit after EOF on stdin and delay of secs p port Specify local port for remote connects P proxyuser Username for proxy authentication N Shutdown the network socket after EOF on stdin m minttl Minimum incoming TTL / Hop Limit k Keep inbound sockets open for multiple connects i interval Delay interval for lines sent, ports scanned OpenBSD netcat (Debian patchlevel 1.217-2ubuntu1) The help output contains options and their descriptions.