help with debugging "Close for unknown channel 0" in dropbear-0.53.1

Matt Johnston matt at ucc.asn.au
Tue May 8 07:54:40 WST 2012


Hi,

If you run Dropbear with "-F -E -v" arguments it will run in the foreground with output to standard output/error. -v turns on the debug output from DEBUG_TRACE. If you send me that I can see if there's anything obvious.

Cheers,
Matt

Bodo Meissner <bodo at bodo-m.de> wrote:

>Hello all,
>
>I need some help with debugging.
>
>I'm using dropbear-0.53.1 on an embedded Linux system and try to use 
>the free SSH.NET library to copy files with SCP inside an application
>on a Windows PC.
>
>On the PC I get errors 
>"An established connection was aborted by the software in your host
>machine." 
>which correspond to syslog messages 
>"authpriv.info dropbear[4775]: Exit (system): Close for unknown channel
>0"
>on the device. (always channel 0)
>
>In the library SSH.NET the remote channel number is always 0 resulting
>in
>channel close messages with channel number 0.
>
>Now I want to find out what's wrong here.
>
>The application on the PC opens an SSH connection and tries to keep it
>open
>permanently for as many SCP transfers (sequentially) as necessary.
>Does dropbear always use the same channel number 0 in this case?
>
>Maybe the library sends a wrong channel number?
>Or it might try to close the same channel twice?
>
>How can I debug this on the device?
>I am able to recompile dropbear for the device, but if possible I don't
>want to use a newer version.
>
>I already compiled dropbear with -DDEBUG_TRACE. It is difficult to see
>the
>output because dropbear redirects most of it to /dev/null.
>
>
>Bodo



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