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Editorial Team
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Asked: 2026-05-31T07:37:47+00:00

Sometimes when connecting to a remote SSH server I get Connection Closed By *IP*;

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Sometimes when connecting to a remote SSH server I get Connection Closed By *IP*; Couldn't read packet: Connection reset by peer. But after trying one or two more times it connects properly.

This presents a problem with a few bash scripts I use to automatically upload my archived backups to the SSH server, like so;

export SSHPASS=$sshpassword
sshpass -e sftp -oBatchMode=no -b - root@$sshaddress << !
   cd $remotefolder
   put $backupfolder/Qt_$date.sql.gz
   bye
!

How can I have this part loop until it actually properly connects?

UPDATE: (Solution)

RETVAL=1
while [ $RETVAL -ne 0 ]
do
export SSHPASS=$sshpassword
sshpass -e sftp -oBatchMode=no -b - root@$sshaddress << !
   cd $remotefolder
   put $backupfolder/Qt_$date.tgz
   bye
!
RETVAL=$?
[ $RETVAL -eq 0 ] && echo Success
[ $RETVAL -ne 0 ] && echo Failure
done
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1 Answer

  1. Editorial Team

    I am not a shell scripting expert, but I would check the return value of sshpass when it exits.

    From man ssh:

    ssh exits with the exit status of the remote command or
with 255 if an error occurred.

    From man sshpath:

    Return Values

    As with any other program, sshpass returns 0 on success. In case of
    failure, the following return codes are used:

    1. Invalid command line argument
    2. Conflicting arguments given
    3. General runtime error
    4. Unrecognized response from ssh (parse error)
    5. Invalid/incorrect password
    6. Host public key is unknown. sshpass exits without confirming the new key.

    In addition, ssh might be complaining about a man in the middle
    attack. This complaint does not go to the tty. In other words, even
    with sshpass, the error message from ssh is printed to standard error.
    In such a case ssh’s return code is reported back. This is typically
    an unimaginative (and non-informative) “255” for all error cases.

    So try to run the command, and check its return value. If the return value was not 0 (for SUCCESS) then try again. Repeat using a while loop until you succeed.

    Sidenote: why are you using sshpass instead of public-key (passwordless) authentication? It is more secure (you don’t have to write down your password) and makes logging in via regular ssh as easy as ssh username@host.

    There’s even an easy tool to set it up: ssh-copy-id.

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