Dropbear 2016.71 issue with Bitvise ssh client v7.15

Matt Johnston matt at ucc.asn.au
Mon Dec 5 21:42:00 AWST 2016


Hi Naveen,

Which sftp-server are you using? Dropbear doesn't ship its own. It would have expected that it would exit when the SSH session exits, because its pipe will be closed.

Do you know what is preventing the second connection - is memory constrained so only one sftp-server process can run?

Cheers
Matt

> On Mon. 5/12/2016, at 3:10 pm, Naveen Mamindlapalli <naveen.mamindlapalli at gmail.com> wrote:
> 
> Hi All,
> 
> I am running Dropbear v2016.74 SSH server from inetd on uClinux OS
> running on ARM cortex M3 processor. When I connected to the SSH server
> using Bitvise ssh client v7.15 with option "open SFTP" enabled (by
> default) in addition to "Open Terminal" option (by default), the
> client successfully connected to the server. The terminal program
> (custom CLI, not linux shell) is accessible. I am not doing any sftp
> transfers during the session.
> 
> After disconnecting the ssh session, I am not able to reconnect again
> from Bitvise ssh client. When I debugged further I found that there is
> a process "cli -c /usr/libexec/sftp-server" still running in the
> background on uClinux Os.
> 
> Workaround:
> I tried following two options to workaround this issue.
> 
> 1. kill cli process manually before reconnecting the client again.
> This works fine.
> 2. disable "Open SFTP" option in Bitvise ssh client. This also works
> fine & no background sftp process is getting created.
> 
> I wanted to know why Dropbear ssh server is not terminating all child
> processes when the connection is terminated from bitvise ssh client.
> Is this a known issue?
> 
> Thanks and Regards,
> Naveen



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