check ssh connection to remote host

Shell Programming and Scripting
1

I am using KSH and I need to check whether the remote host has been configured with ssh public key. Is there any way we can check inside a script?

2

man test

host=host
ssh $host "echo 2>&1"
test $? -eq 0 && echo $host OK || echo $host NOK
3

Of course, that's a Useless Use of Test $?

ssh $host "echo 2>&1" && echo $host OK || echo $host NOK

Absence of a public key is by no means the only way the ssh command can fail, so this is an approximation at best; but maybe it's sufficient.

4

:b: This time I use test only as example to show him how to use the exit status.

5

Great thanks , This is helpfull.

6

I got a problem here

I removed the public key config on the ssh server and then tried

ssh root@$host "echo 2>&1" && echo "OK" || echo "NOK"

But it came out asking password . which I dont want , what I wanted is even if its asked passwd its should come out with a non-zero exit satus.

--------------------------------------------------------------------
Now let say how I got it implemented , even though a twisted way

if [ -f $HOME/.ssh2/ssh2_config ]
then
mv $HOME/.ssh2/ssh2_config $HOME/.ssh2/ssh2_config.bkp
echo "QuietMode yes\nBatchMode yes\nConnectTimeout 4" > $HOME/.ssh2/ssh2_config
else
echo "QuietMode yes\nBatchMode yes\nConnectTimeout 4" > $HOME/.ssh2/ssh2_config
fi

ssh -l root $R_HOSTNAME "date" > /dev/null
CONN_STATUS=$?

And if the RC is 66 , then it mean it had asked passwd and not got passwd within in the timeout period. Andas usual 0 as success.

7 
ssh -q -o "BatchMode=yes" user@host "echo 2>&1" && echo "OK" || echo "NOK"

...will solve your problem, by running quietly and in batch mode (no user present to enter a password). See man ssh_config for more details. Obviously the two echo statements can be replaced with any action you like...

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