Netcat usage examples

June 4, 2009

The following commands were done on the Linux version of Netcat.

Connect to TCP port 80 on host example.com:

nc -vv example.com 80

Port scan TCP ports 7 through 1023 on host example.com

nc -v -z example.com 7-1023

Port scan TCP ports 7 through 1023 on host example.com, but stop for user interaction on open ports

nc -v example.com 7-1023

Port scan UDP ports 53 through 69 on host example.com

nc -v -z -u example.com 53-69

Listen for inbound connections on TCP port 1234 and pipe the results to a file data.txt

nc -vv -l 1234 > data.txt

Listen for inbound connections on TCP port 25 and pipe the results to /dev/null

nc -vv -l 25 > /dev/null

Listen for inbound connections on TCP port 25 and pipe the results to /dev/null, but keep listening on the port even after a disconnect.

nc -vv -k -l 25 > /dev/null

Listen for inbound connections on TCP port 25, keep listening on the port open even after a disconnect, but automatically drop any session after 3 seconds of inactivity.

nc -vv -k -w 3 -l 25

Listen for inbound connections on TCP port 25, automatically pushing the contents of file welcome.txt upon a connection.

cat welcome.txt | nc -vv -l 25

Transfer contents of file payload.txt to host example.com using TCP port 1234

nc -vv example.com 1234 < payload.txt

Transfer the image of device /dev/sda1 to host example.com using TCP port 1234

dd if=/dev/sda1 | nc -vv example.com 1234