Hash mismatch when SSHing to dropbear server

Hans-Christian Egtvedt hcegtvedt at atmel.com
Thu Aug 3 22:18:44 WST 2006


Hi

I've compiled dropbear for the avr32 platform, the compilation goes
about without any problems, although there is alot of "differ in
signedness" warnings.

The problem is that it works fine ssh'ing from the avr32 => avr32, but I
can't ssh from my workstation (Intel P4 running Ubuntu Dapper).

Could the hash mismatch openssh reports on my workstation be related to
a big-endian vs. little-endian bug/issue in the dropbear software?

The avr32 is big-endian.

Debug from ssh to the avr32 running dropbear 0.48.1.

debug1: Remote protocol version 2.0, remote software version dropbear_0.48
debug1: no match: dropbear_0.48
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_4.2p1 Debian-7ubuntu3
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-cbc hmac-md5 none
debug1: kex: client->server aes128-cbc hmac-md5 none
debug1: sending SSH2_MSG_KEXDH_INIT
debug1: expecting SSH2_MSG_KEXDH_REPLY
The authenticity of host '10.191.252.83 (10.191.252.83)' can't be
established.
RSA key fingerprint is 3b:26:ee:d2:5b:5b:ba:5d:07:37:f2:4c:89:67:ba:14.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '10.191.252.83' (RSA) to the list of known hosts.
hash mismatch
debug1: ssh_rsa_verify: signature incorrect
key_verify failed for server_host_key

Syslog on the avr32 running dropbear:

Aug  3 14:07:39 10 authpriv.info dropbear[571]: Child connection from
10.191.252.128:37507
Aug  3 14:07:43 10 authpriv.info dropbear[571]: exit before auth: error
reading: Connection reset by peer

The same applies if I use a dss key.

Any hints or tips to where I should start attacking would be great (-:

-- 
With kind regards,
Med vennlig hilsen,

Hans-Christian Egtvedt
Applications Engineer - AVR Applications Lab
Atmel Norway



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