Dropbear 2018.76

Thu Mar 8 22:28:28 AWST 2018

Hi Peter,

This should be fixed in https://secure.ucc.asn.au/hg/dropbear/rev/0dc3103a5900 <https://secure.ucc.asn.au/hg/dropbear/rev/0dc3103a5900>

Dropbear was advertising both the existing ecdsa size as well as the default size (for -R), 
but then the client chose the default size which didn't match the key that had been loaded.
Now it only advertises a single size - first preference existing size, otherwise the default if no 
key exists.
Thanks for letting me know and debugging.

Cheers,
Matt

> On Mon 5/3/2018, at 4:02 pm, Peter Krefting <peter at softwolves.pp.se> wrote:
> 
> Matt Johnston:
> 
>> Yes it should. I can't immediately reproduce it here, what
>> flags are you giving to Dropbear? Is
>> /mnt/nv/dropbear_ecdsa_host_key specified with -r or as a
>> default config path, and are there other keyfiles?
> 
> The daemon is started with "dropbear -R", and the keyfiles are specified at compile-time, using localoptions.h. The full file is included below.
> 
>> ssh -vvv will print the full set of negotiated algorithms,
>> you could send that to me (off-list if you want).
> 
> I have included the output below
> 
>> The relevant revision for that changelog note is
>> https://secure.ucc.asn.au/hg/dropbear/rev/016b86f03e21
>> you could try reverting that to confirm.
> 
> That does not seem to fix the issue, it aborts in the same location, so it seems something else is going on here.
> 
> 
> ===[ localoptions.h ]===
> /* Put host keys in non-volatile storage */
> #define DSS_PRIV_FILENAME "/mnt/nv/dropbear_dss_host_key"
> #define RSA_PRIV_FILENAME "/mnt/nv/dropbear_rsa_host_key"
> #define ECDSA_PRIV_FILENAME "/mnt/nv/dropbear_ecdsa_host_key"
> 
> /* Disable inetd mode */
> #define INETD_MODE 0
> 
> /* Disable X11 forwarding as we do not have any X11. */
> #define DROPBEAR_X11FWD 0
> 
> /* Disable port forwarding and proxying and agent forwarding. */
> #define DROPBEAR_CLI_LOCALTCPFWD 0
> #define DROPBEAR_CLI_REMOTETCPFWD 0
> #define DROPBEAR_SVR_LOCALTCPFWD 0
> #define DROPBEAR_SVR_REMOTETCPFWD 0
> #define DROPBEAR_SVR_AGENTFWD 0
> #define DROPBEAR_CLI_AGENTFWD 0
> #define DROPBEAR_CLI_PROXYCMD 0
> #define DROPBEAR_CLI_NETCAT 0
> 
> /* Disable Twofish to save about 10 kilobytes. */
> #define DROPBEAR_TWOFISH256 0
> #define DROPBEAR_TWOFISH128 0
> 
> /* Disable /etc/motd support since nothing else on the target uses it. */
> #define DO_MOTD 0
> 
> /* Put client keys in non-volatile storage */
> #define DROPBEAR_DEFAULT_CLI_AUTHKEY "/mnt/nv/id_dropbear"
> 
> /* Disable sftp support (as we do not have a binary for sftp installed). */
> #define DROPBEAR_SFTPSERVER 0
> 
> /* Patch it to use the same default PATH as the telnet daemon. This will
> * fix scripts that assume certain tools are in the path. */
> #define DEFAULT_PATH "/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin"
> ===[ end localoptions.h ]===
> 
> ===[ output from ssh -vvvv ]===
> $ ssh -vvvv root at 10.0.30.175
> OpenSSH_7.4p1 Debian-10+deb9u2, OpenSSL 1.0.2l  25 May 2017
> debug1: Reading configuration data /home/peter/.ssh/config
> debug1: /home/peter/.ssh/config line 54: Applying options for 10.0.30.175
> debug1: Reading configuration data /etc/ssh/ssh_config
> debug1: /etc/ssh/ssh_config line 19: Applying options for *
> debug2: resolving "10.0.30.175" port 22
> debug2: ssh_connect_direct: needpriv 0
> debug1: Connecting to 10.0.30.175 [10.0.30.175] port 22.
> debug1: Connection established.
> debug1: identity file /home/peter/.ssh/id_rsa type 1
> debug1: key_load_public: No such file or directory
> debug1: identity file /home/peter/.ssh/id_rsa-cert type -1
> debug1: key_load_public: No such file or directory
> debug1: identity file /home/peter/.ssh/id_dsa type -1
> debug1: key_load_public: No such file or directory
> debug1: identity file /home/peter/.ssh/id_dsa-cert type -1
> debug1: key_load_public: No such file or directory
> debug1: identity file /home/peter/.ssh/id_ecdsa type -1
> debug1: key_load_public: No such file or directory
> debug1: identity file /home/peter/.ssh/id_ecdsa-cert type -1
> debug1: key_load_public: No such file or directory
> debug1: identity file /home/peter/.ssh/id_ed25519 type -1
> debug1: key_load_public: No such file or directory
> debug1: identity file /home/peter/.ssh/id_ed25519-cert type -1
> debug1: Enabling compatibility mode for protocol 2.0
> debug1: Local version string SSH-2.0-OpenSSH_7.4p1 Debian-10+deb9u2
> debug1: Remote protocol version 2.0, remote software version dropbear_2018.76
> debug1: no match: dropbear_2018.76
> debug2: fd 3 setting O_NONBLOCK
> debug1: Authenticating to 10.0.30.175:22 as 'root'
> debug3: hostkeys_foreach: reading file "/home/peter/.ssh/known_hosts"
> debug3: record_hostkey: found key type ECDSA in file /home/peter/.ssh/known_hosts:126
> debug3: load_hostkeys: loaded 1 keys from 10.0.30.175
> debug3: order_hostkeyalgs: prefer hostkeyalgs: ecdsa-sha2-nistp256-cert-v01 at openssh.com,ecdsa-sha2-nistp384-cert-v01 at openssh.com,ecdsa-sha2-nistp521-cert-v01 at openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521
> debug3: send packet: type 20
> debug1: SSH2_MSG_KEXINIT sent
> debug3: receive packet: type 20
> debug1: SSH2_MSG_KEXINIT received
> debug2: local client KEXINIT proposal
> debug2: KEX algorithms: curve25519-sha256,curve25519-sha256 at libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha256,diffie-hellman-group14-sha1,ext-info-c
> debug2: host key algorithms: ecdsa-sha2-nistp256-cert-v01 at openssh.com,ecdsa-sha2-nistp384-cert-v01 at openssh.com,ecdsa-sha2-nistp521-cert-v01 at openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-ed25519-cert-v01 at openssh.com,ssh-rsa-cert-v01 at openssh.com,ssh-ed25519,rsa-sha2-512,rsa-sha2-256,ssh-rsa
> debug2: ciphers ctos: chacha20-poly1305 at openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm at openssh.com,aes256-gcm at openssh.com,aes128-cbc,aes192-cbc,aes256-cbc
> debug2: ciphers stoc: chacha20-poly1305 at openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm at openssh.com,aes256-gcm at openssh.com,aes128-cbc,aes192-cbc,aes256-cbc
> debug2: MACs ctos: umac-64-etm at openssh.com,umac-128-etm at openssh.com,hmac-sha2-256-etm at openssh.com,hmac-sha2-512-etm at openssh.com,hmac-sha1-etm at openssh.com,umac-64 at openssh.com,umac-128 at openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
> debug2: MACs stoc: umac-64-etm at openssh.com,umac-128-etm at openssh.com,hmac-sha2-256-etm at openssh.com,hmac-sha2-512-etm at openssh.com,hmac-sha1-etm at openssh.com,umac-64 at openssh.com,umac-128 at openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
> debug2: compression ctos: none,zlib at openssh.com,zlib
> debug2: compression stoc: none,zlib at openssh.com,zlib
> debug2: languages ctos: debug2: languages stoc: debug2: first_kex_follows 0 debug2: reserved 0 debug2: peer server KEXINIT proposal
> debug2: KEX algorithms: curve25519-sha256,curve25519-sha256 at libssh.org,ecdh-sha2-nistp521,ecdh-sha2-nistp384,ecdh-sha2-nistp256,diffie-hellman-group14-sha256,diffie-hellman-group14-sha1,kexguess2 at matt.ucc.asn.au
> debug2: host key algorithms: ecdsa-sha2-nistp256,ecdsa-sha2-nistp521,ssh-rsa,ssh-dss
> debug2: ciphers ctos: aes128-ctr,aes256-ctr,aes128-cbc,aes256-cbc,3des-ctr,3des-cbc
> debug2: ciphers stoc: aes128-ctr,aes256-ctr,aes128-cbc,aes256-cbc,3des-ctr,3des-cbc
> debug2: MACs ctos: hmac-sha1-96,hmac-sha1,hmac-sha2-256
> debug2: MACs stoc: hmac-sha1-96,hmac-sha1,hmac-sha2-256
> debug2: compression ctos: zlib at openssh.com,none
> debug2: compression stoc: zlib at openssh.com,none
> debug2: languages ctos: debug2: languages stoc: debug2: first_kex_follows 0 debug2: reserved 0 debug1: kex: algorithm: curve25519-sha256
> debug1: kex: host key algorithm: ecdsa-sha2-nistp256
> debug1: kex: server->client cipher: aes128-ctr MAC: hmac-sha2-256 compression: none
> debug1: kex: client->server cipher: aes128-ctr MAC: hmac-sha2-256 compression: none
> debug3: send packet: type 30
> debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
> Connection closed by 10.0.30.175 port 22
> ===[ end output from ssh -vvvv ]===
> 
> -- 
> \\// Peter - http://www.softwolves.pp.se/

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