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Is there an easy way for a non root user to find if a port is open ?

As I non root user ( nmap is not installed) I want to find out if I can ssh to a box.  

I tried telnet  x.y.z.a  22 and if it is open, it show on the screen and then does not terminate process so my script can do something.  If it is not open, I still have a process that stays open for too long.

what I am looking for is
$ line of code
$ if $? then xxxx

I am in a large network and some systems are available from some ip's and in other environments they are not .



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TIMFOX123
Asked:
TIMFOX123
1 Solution
 
farzanjCommented:
It is installed but non-root account doesn't have the priviledge.

So, for example, the following should do it:
sudo nmap -sS  localhost

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farzanjCommented:
You have to setup sudo privileges for this user.  You can also set it up without password.

Second, if you want to do with remotely using ssh, the command would be
ssh host.domain.com sudo "nmap -v -sS localhost"

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woolmilkporcCommented:
If you don't have sudo permission, try this script I once wrote here at EE:

#!/bin/sh
CHECKFILE=/tmp/sshchk.$$
PORT=22
HOST=hostname
SLEEPTIME=2

rm $CHECKFILE 2>/dev/null
( telnet $HOST $PORT 2>&1 ) > $CHECKFILE &
JOB=$!
   sleep $SLEEPTIME
   kill $JOB 2>/dev/null

if grep -q "Connected to" $CHECKFILE ; then
   echo SSH Server on $HOST is UP
  else
   echo SSH Server on $HOST is DOWN
fi
rm $CHECKFILE 2>/dev/null
exit

wmp
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Saikapian_4739Commented:
I guess you can use netstat to see if a port is open or not. Here is the syntax

netstat -ntlp |grep port number

You can omit the p option if you want, it will show you the program that is holding the port you are looking for. For example in your case

netstat -ntlp | grep 22

Will show no output if port 22 is not open, but if it is open it ll show you the output giving you details like program holding the port, whether port is at Listen status or connection is Established also to what IP addresses the port is listening to.

Thanks
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TIMFOX123Author Commented:
What a great solution !!!

great

Kudos

did the impossable

thx.
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