dropbear client : No auth methods could be used (again !)

[Stephane]

Hi,

We develop an alternative firmware for NAS with Dropbear as SSH server
(0.53.1).
When we try to open an SSH access with dbclient command from a first NAS to
a second NAS (with the same firmware), we have this error message when using
key authentication mode :

Dropbear daemon with command :
- dropbear -s -r /rw_fs/etc/dropbear/dropbear_rsa_host_key

SSH access attempt :
- dbclient -i /rw_fs/etc/dropbear/dropbear_rsa_host_key root at 192.168.x.y
echo '$PATH'
dbclient: Connection to root at 192.168.x.y 22 exited: No auth methods could be
used.

By against, if we use password authentication mode,SSH access is open :
dbclient root at 192.168.x.y echo '$PATH'
root at 192.168.x.y's password:
/usr/bin:/bin:/sbin:/usr/sbin

Public keys of each server (dropbearkey-y-f ...) are saved reciprocally in
each file "authorized_keys" (pubkey_nas1 => authorized_keys_nas2, and
reversely).
The authorized_keys files are located in the folder "/.ssh" and with correct
permissions (700 /. ssh and 644 authorized_keys)

Dropbear compilation options :
./configure --prefix=/usr

and in options.h
/* The default path. This will often get replaced by the shell */
#define DEFAULT_PATH "/usr/bin:/bin:/sbin:/usr/sbin"

When we use option -F and -E, dropbear returns thhis :
[3815] Oct 10 23:17:31 Child connection from 192.168.x.y:36259
[3815] Oct 10 23:17:32 Exit before auth (user 'root', 0 fails): Exited
normally

What is the problem ?

Thanks in advance