SSH Connectivity script

UNIX for Advanced & Expert Users
1

Hi all,

I have developed a script to list out the servers that is not able to connect to the remote host.

The problem with this script is it, if the remote server ask for a password it gets struck there. It works only if the server name is invalid

Ex: Lets say ssh -q test@test "exit" < /dev/null the script will throw that test server is invalid.

Lets say now UserA and ServerA is valid but when we ssh to the server, it ask for a password and script hangs

ssh -q UserA@ServerA "exit" < /dev/null

Code

check_ssh()
{
        ssh -q $1@$2 "exit" < /dev/null
        [ $? -ne "0" ] && return 1 || return 0
}

INP_FILE=Config.ini

for line in $(grep -v "^#" $INP_FILE | cut -d',' -f2,5 | sort | uniq)
do
        myUser=$(echo $line| cut -d',' -f2)
        myServer=$(echo $line| cut -d',' -f1)
        check_ssh $myUser $myServer
        [ $? -eq "1" ] && echo "Please check !!! $myServer - $myUser"
done
echo " *** END *** "
exit
2

i understand you basic idea is to use ssh do a dummy connect to figure out if an sshd is running on the other side ?

why do you not use nmap ? it simply cheks if there is a service available,

3

I will check that option, any other ??

4

... but what are you exacly testing for?
Whether you can connect or not?
Whether sshd is running or not?
If you can connect to the hosts without a pasword using ssh keys?

5

I want to check if we can ssh to a remote host and execute our statements. This is just a function block which checks for whether we can ssh into a server before executing our statements.

I just want to capture the server names that we are not able to ssh, so that we can skip those servers from executing the command.

Hope this makes clear !!

6 
check_ssh()
{
        ssh -q -o "BatchMode=yes" $1@$2 "exit" < /dev/null
        [ $? -ne "0" ] && return 1 || return 0
}

INP_FILE=Config.ini

for line in $(grep -v "^#" $INP_FILE | cut -d',' -f2,5 | sort | uniq)
do
        myUser=$(echo $line| cut -d',' -f2)
        myServer=$(echo $line| cut -d',' -f1)
        check_ssh $myUser $myServer
        [ $? -eq "1" ] && echo "Please check !!! $myServer - $myUser"
done
echo " *** END *** "
exit