Interop problem with old dropbear and new openssh

Rob Landley rob at
Sun Oct 2 02:58:30 WST 2011

On 09/30/2011 04:38 PM, Graham Cobb wrote:
> Hi,
> I have a router running an old version of OpenWRT with an old version of 
> dropbear (Dropbear sshd v0.44test3).  It has been working for many years and I 
> ssh in from my desktop systems (running Debian Testing) with no problem.
> However, recently I upgraded one of my desktops and I can no longer connect to 
> the router.  Dropbear on the router is exiting with:
> exit before auth: bad buf_getwriteptr
> The desktop is running "SSH-2.0-OpenSSH_5.9p1 Debian-1" (it failed with 5.8 as 
> well).  However, another desktop still running "SSH-2.0-OpenSSH_5.5p1 
> Debian-6" still works fine.  The config files are identical.
> I realise this is a very old version of dropbear and that you are not 
> responsible for changes in OpenSSH but I thought I would ask here in case 
> anyone else has seen this and can maybe suggest a config change to workround 
> the problem!
> Graham

If you'd like to try the current version, statically linked binaries of
current dropbearmulti for several of architectures are at:


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