Open telnet and send commands on a single bash line

pedropt · 11-22-2019, 01:19 PM

I am trying to execute a mail read using telnet on pop3 port , however i did not had any luck .
My objective is to connect with telnet using a line in bash , get all the stats from specific username to a file .

Code:

#!/bin/bash
user="USER someuser@someserver"
pass="PASS password"
server="mailserver"
port="110"

telnet $server $port | sleep 1 | echo $user | sleep 1 | echo $pass | sleep 1 | echo STATS | echo QUIT > file >/dev/null 2>&1
echo "Done"
exit 0

Ideas ?

michaelk · 11-22-2019, 01:36 PM

I know it is possible using an expect script. I also think you can pipe commands from a file into telnet as if you typed them in during a session. You should be able to do something similar with netcat.

cat commands.txt | telnet

pedropt · 11-22-2019, 03:13 PM

using cat to pipe the commands did not worked out .
i tried with nc with also the same issue , cant pipe the commands to the program in execution .

I also did a loop , but it stays hanged , i have to run it with bash -x to see what happened .

Code:

#!/bin/bash
user="USER someuser@someserver"
pass="PASS password"
server="mailserver"
port="110"
while nc $server $port
do
echo $user 
echo $pass 
echo STATS 
echo QUIT 
done > file 
echo "Done"
exit 0

I already saw somewhere on the web an example using expect , however i am trying to use it with less tools as possible .

scasey · 11-22-2019, 04:14 PM

My pop3 server on port 110 doesn't understand the echo command.
I can get a script to hang waiting for the user and pass. A here document didn't work either.
passing the commands from a file didn't work for me either...at least I didn't get the result from the stat

Perhaps the expect script is the only way.

pedropt · 11-22-2019, 04:16 PM

my last attempt here was to wait for the logged file from telnet or nc to show the commands and then the script execute next command , but somehow i can`t insert the commands into nc or telnet .

Code:

#!/bin/bash
user="USER someuser@someserver"
pass="PASS password"
server="mailserver"
port="110"
dove () {
if [[ "$i" == "1" ]]
then
a1=$(tail -1 connect | grep "+OK Dovecot ready.")
if [[ ! -z "$a1" ]]
then
echo $user
else
sleep 0.5
dove
fi
elif [[ "$i" == "2" ]]
then
a1=$(tail -1 connect | grep "+OK")
if [[ ! -z "$a1" ]]
then
echo $pass
else
sleep 0.5
dove
fi
elif [[ "$i" == "3" ]]
then
a1=$(tail -1 connect | grep "+OK Logged in.")
if [[ ! -z "$a1" ]]
then
echo STAT
else
sleep 0.5
dove
fi
elif [[ "$i" == "4" ]]
then
a1=$(tail -1 connect | grep "+OK")
if [[ ! -z "$a1" ]]
then
echo QUIT
else
sleep 0.5
dove
fi
fi
telnet $server $port | tee connect &
for i in "seq 1 4"
do
dove
done
exit 0

Probably the problem here is that i need to insert an "ENTER" command after every instruction on telnet or nc .

I am able to put this code working but using a different method that i am trying to avoid , witch using ttyecho script , basically i have to open a another shell and then use ttyecho to write all these commands there , but if i can avoid it then would be awesome .

I will wait a few days to see if someone here knows how to do this .

scasey · 11-22-2019, 04:41 PM

Another thought. Perhaps you are "re-inventing the wheel"
There are existing command-line utilities for retrieving email. fetchmail is one. This search pulled up more information.

Just a thought.

michaelk · 11-22-2019, 07:10 PM

Silly me... I would agree if you want to write your own script that expect is the only way but using an existing utility is a better choice.

pedropt · 11-22-2019, 09:52 PM

Quote:

Another thought. Perhaps you are "re-inventing the wheel"
There are existing command-line utilities for retrieving email. fetchmail is one. This search pulled up more information.

Just a thought.

This is not just to grab the email , if it was just to watch my email then i would use roundcube , this script will be used to execute commands that i will send to a specific email address .
So , the script will see every x time if any email exists in some account , case exists then retrieve the email by email to local folder , then delete those emails from the account , and then after parsing the emails on local folder for who sent and witch commands were requested it will execute them on server .

Look , i need to write this script because there is nothing ever done like this , usually by default a sys admin connect to a server using a ssh and execute what he needs , i can also do that , and i do it , but when you are on an android phone somewhere with a small display and with a complex ssh login connection as i have in my server it is impossible , not even mention if your phone is not rooted and you dont have most of the tools to do this job .

so if i send "video add 1.1.1.1" as a subject , then my script will interpret that i want to add the ip 1.1.1.1 to the video streaming location in firewall , but if i write "video rem 1.1.1.1" then it will remove that ip from firewall , and this is just a sample of what will do .

I will always find a way to make it work , maybe i will use expect or tty echo , but only if no solution appear here witch i have some doubts because there is always someone here that knows how to do it , i never saw here anything that did not had a solution .

Anyway , i was looking in this code :
https://www.cyberciti.biz/tips/remov...p3-server.html

This code executes 2 scripts at same time to do the job , 1 is the telnet connection to server and the other are the commands .

UPDATE

Well , expect is out of question , it looks it needs its own interpreter to run , witch means i have to create a new script with the commands to be able to run in expect .

ttyecho won the prize .
http://www.humbug.in/2010/utility-to...minals-ttypts/

After compilation i only need to launch telnet on another tty , like

Quote:

setsid sh -c 'exec telnet $server $port > connect <> /dev/tty9 >&0 2>&1' &

and then from this script everything can be done with these commands :

Quote:

ttyecho -n tty? USER someusername

and etc ....