Simplest port scanner

for p in {1..1023}; do(echo >/dev/tcp/localhost/$p) >/dev/null 2>&1 && echo "$p open"; done
Very handy way to perform a host scan if you don't have nmap,ncat,nc ...or other tools installed locally. When executing a command on a /dev/tcp/$host/$port pseudo-device file, Bash opens a TCP connection to the associated socket and UDP connection when using /dev/udp/$host/$port.A simlpe way to get servers banner is to run this command "cat < /dev/tcp/localhost/25" , here you will get mail server's banner. NOTE: Bash, as packaged for Debian, does not support using the /dev/tcp and /dev/udp pseudo-device it's not enabled by default Because bash in Debian is compiled with ?disable-net-redirections.
Sample Output
22 open
25 open
53 open
80 open
110 open
111 open
143 open

4
By: benyounes
2010-04-26 18:09:22

What Others Think

Stolen but cool. #10: Bash Socket Programming http://www.cyberciti.biz/tips/spice-up-your-unix-linux-shell-scripts.html
meathive · 438 weeks ago

What do you think?

Any thoughts on this command? Does it work on your machine? Can you do the same thing with only 14 characters?

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