[SOLVED] Anyone know how to get inetd to create a file when a new connection is made?

arfon · 10-07-2022, 04:45 PM

Code:

nc -l -p 5555 > /root/test.txt

...receives connection/data fine but, I don't want nc running all of the time. I want inetd accept the connection and dump the message to a file.

I have tried:

/etc/services-

Code:

 myservice 5555/tcp

/etc/inetd.conf-

Code:

myservice stream tcp nowait root /bin/sh sh -c "cat > /root/test.txt"

and

Code:

myservice stream tcp nowait root /bin/sh sh -c "nc -l -p 5555 > /root/test.txt"

The 'sending machine' doesn't complain about "connection refused" so it looks like inetd is accepting the connection but, the files are not being created.

I even tried:

Code:

myservice stream tcp nowait root /bin/sh sh -c "touch /root/test.txt"

...and test.txt is not getting created.

UPDATE: Inetd doesn't like the commands above nor does it like command I'm using on the sending machine...

*** SOLUTION ***
MACHINE 1 /etc/services add:

Code:

myservice 5555/tcp

Machine 1 /etc/inetd.conf add:

Code:

myservice stream tcp nowait root /root/tcpread.sh

Machine 1 create /root/tcpread.sh:

Code:

#!/bin/bash
while IFS= read -r line; do
 echo "$line" >> /root/tcpout.txt
done

Machine 1:

Code:

chmod 755 /etc/rc.d/rc.inetd
/etc/rc.d/rc.inetd start
chmod 755 /root/tcpread.sh

Machine 2 (send a message):

Code:

echo -n 'Line of text' | nc machine1 5555

(TY MichaelK)

michaelk · 10-07-2022, 05:59 PM

Why are you still using inetd versus xinetd?
I have not played with inetd in many many years but the fields are defined as

Quote:

service-name
socket-type
protocol[,sndbuf=size][,rcvbuf=size]
wait|nowait[:max]
user[:group]
server-program
server program arguments

I would not expect you could actually execute a command as posted but then again I have never tried.
I would create a bash script to accept input from stdin and write to file. Something like:

Code:

#!/bin/bash
while IFS= read -r line; do
 echo "$line" >> /root/test.txt
done

If you save the script to /root then use.

Code:

myservice stream tcp nowait root /root/script.sh

Make sure you restart inetd.

arfon · 10-07-2022, 11:01 PM

"Why are you still using inetd versus xinetd?"
I'm running vanilla Slackware.

Unfortunately, the script.sh solution didn't work. It's still not making a file.

UPDATE: MichaelK, your solution IS working... For some reason inetd isn't liking the command I'm using on the other computer to send the data:

Code:

exec 3<>/dev/tcp/machine1/5555; echo -ne "some data" >&3