runshell script for each netcat output 1

[geebers]

is there an efficient way to fire off a shell script each time netcat receives new text string from a network port?

i need root to run myscript.sh each time a new string of text is received from port 3333. also, capture the string as a variable in myscript.sh.

thanks for any help.
m

 

[feherke]

Hi

Depends on the [tt]netcat[/tt] implementation you use. And also depends on your exact task. Generally would be better to run myscript.sh once and let it handle all the output :

netcat -l -p 3333 -e myscript.sh

[gray]# or[/gray]

netcat -l -p 3333 | myscript.sh

But you really want to process each line of data with another process :

netcat -l -p 3333 | while read str; do myscript.sh "$str"; done

Additionally I would take a look at [tt]inetd[/tt], [tt]xinetd[/tt] or other internet super-servers.


Feherke.

http://free.rootshell.be/~feherke/

 

[geebers]

hmmm, I think xinetd is what i'm after. I just want to run myscript.sh when some text is sent to port 3333, using UDP.

so i installed xinetd from my repos and added the following line to /etc/services
myscript 3333/udp

created the file /etc/xinetd.d/myscript and it contains...

service myscript
{
port = 3333
socket_type = dgram
wait = no
user = fred
server = /home/fred/myscript.sh
log_on_success += USERID
log_on_failure += USERID
disable = no
}

Then I restart xinetd.

Then open port 3333 on firewall.
Now if I use netcat to send some text, myscript.sh does not run. My netcat command is....
sudo nc -u 192.168.2.321 3333

and then I type in text from stdin. But myscript.sh does not run.

Any help?

 

[Annihilannic]

Is there any particular reason why you are using UDP?

If you add an entry to /etc/services called "myscript 3333/udp" it should work. You should have received some error messages from xinetd in your system log.

Annihilannic.

 

[geebers]

i have a digital signage device that uses upd to communicate.

I got it working. To use udp for a service, there are two required lines in /etc/xinetd.d/myscript ....

socket_type = dgram
wait = yes

default settings are:
socket_type = stream
wait = no

So here's my working /etc/xinetd.d/myscript file

service myscript
{
port = 3333
socket_type = dgram
wait = yes
user = fred
server = /home/fred/myscript.sh
log_on_success += USERID
log_on_failure += USERID
disable = no
}

thanks feherke for showing me the right tool to use!