Re: Regarding Putty is not connecting to lib SSH server - HMAC Error

[Andreas Schneider <asn@xxxxxxxxxxxxxx>]

On Wednesday 19 June 2013 10:01:41 Ashish Mangla wrote:
> Hi
> 
>  We are using your LIBSSH server and customized it to meet our needs. Today
> I am trying to connect the server with putty but unfortunately I am getting
> the following error. To check this I have written one LIBSSH client and it
> seems that the LIBSSH server works fine with the custom client (which I
> wrote, with same kind of messages what putty is sending). Can you help us
> what is going wrong with putty. I am attaching both client and server code
> along with the keys (these keys I have collected from one my Linux server)
> used.
> 
> Please find the error reported and corresponding putty log.
> 
> [cid:image001.png@01CE6B85.DBA37C70]
> 
> Server Log with custom client ..,
> 
> [3] Enabling POLLOUT for socket
> [3] ssh_handle_key_exchange: Actual state : 2
> [3] Received banner: SSH-2.0-libssh-0.5.0
> [1] SSH client banner: SSH-2.0-libssh-0.5.0
> [1] Analyzing banner: SSH-2.0-libssh-0.5.0
> [3] Writing on the wire a packet having 347 bytes before
> [3] 347 bytes after comp + 8 padding bytes = 356 bytes packet
> [3] Enabling POLLOUT for socket
> [3] ssh_handle_key_exchange: Actual state : 4
> [3] ssh_handle_key_exchange: Actual state : 4
> [3] Packet size decrypted: 148 (0x94)
> [3] Read a 148 bytes packet
> [3] 6 bytes padding, 147 bytes left in buffer
> [3] After padding, 141 bytes left in buffer
> [3] Final size 141
> [3] Type 20
> [3] Dispatching handler for packet type 20
> [3] Set output algorithm aes256-ctr
> [3] Set input algorithm aes256-ctr
> [3] ssh_handle_key_exchange: Actual state : 6
> [3] Packet size decrypted: 140 (0x8c)
> [3] Read a 140 bytes packet
> [3] 5 bytes padding, 139 bytes left in buffer
> [3] After padding, 134 bytes left in buffer
> [3] Final size 134
> [3] Type 30
> [3] Dispatching handler for packet type 30
> [3] Received SSH_MSG_KEXDH_INIT
> [3] Writing on the wire a packet having 689 bytes before
> [3] 689 bytes after comp + 10 padding bytes = 700 bytes packet
> [3] Enabling POLLOUT for socket
> [3] Writing on the wire a packet having 1 bytes before
> [3] 1 bytes after comp + 10 padding bytes = 12 bytes packet
> [3] SSH_MSG_NEWKEYS sent
> [3] ssh_handle_key_exchange: Actual state : 6
> [3] Packet size decrypted: 12 (0xc)
> [3] Read a 12 bytes packet
> [3] 10 bytes padding, 11 bytes left in buffer
> [3] After padding, 1 bytes left in buffer
> [3] Final size 1
> [3] Type 21
> [3] Dispatching handler for packet type 21
> [2] Received SSH_MSG_NEWKEYS
> [3] Enabling POLLOUT for socket
> [3] ssh_handle_key_exchange: Actual state : 7
> [3] Decrypting 16 bytes
> [3] Packet size decrypted: 28 (0x1c)
> [3] Read a 28 bytes packet
> [3] Decrypting 16 bytes
> [3] 10 bytes padding, 27 bytes left in buffer
> [3] After padding, 17 bytes left in buffer
> [3] Final size 17
> [3] Type 5
> [3] Dispatching handler for packet type 5
> [3] Received a SERVICE_REQUEST for service ssh-userauth
> [3] Sending a SERVICE_ACCEPT for service ssh-userauth
> [3] Writing on the wire a packet having 17 bytes before
> [3] 17 bytes after comp + 10 padding bytes = 28 bytes packet
> [3] Encrypting packet with seq num: 3, len: 32
> [3] Enabling POLLOUT for socket
> [3] Decrypting 16 bytes
> [3] Packet size decrypted: 44 (0x2c)
> [3] Read a 44 bytes packet
> [3] Decrypting 32 bytes
> [3] 19 bytes padding, 43 bytes left in buffer
> [3] After padding, 24 bytes left in buffer
> [3] Final size 24
> [3] Type 90
> [3] Dispatching handler for packet type 90
> [3] Clients wants to open a session channel
> [3] Writing on the wire a packet having 17 bytes before
> [3] 17 bytes after comp + 10 padding bytes = 28 bytes packet
> [3] Encrypting packet with seq num: 4, len: 32
> [3] Enabling POLLOUT for socket
> 
> 
> It seems it's fine with the custom client.
> 
> /Ashish

I will try to find some time to look into it.

-- 
Andreas Schneider                   GPG-ID: F33E3FC6
www.cryptomilk.org                asn@xxxxxxxxxxxxxx