Re: HMAC error - help pls

[Aris Adamantiadis <aris@xxxxxxxxxxxx>]

Hi,

I have inspected the code path, there is no possibility for "decrypting
16 bytes" message to show up twice in a row. Are you using several
sessions ? If so, could you try again but with only one client ? I'm not
yet sure it's not a libssh problem so I prefer we investigate.

Kr,

Aris

Le 7/06/11 13:22, jeetu.golani@xxxxxxxxx a écrit :
> Hi Aris,
> 
> Thanks for replying.
> 
> Unfortunately I copy pasted only this part of the log, will reproduce
> the error and paste the entire log.
> 
> As for an estimation on the amount of data, gauging that the packet
> number above is 36519 and while most packets seemed to have a length
> of 32bytes, I did see some packets with a length of 668bytes too
> (about 10%).....am guessing approx 35 Megabytes of data.
> 
> For the ssh client I am using a standard openssh client, the server is
> my own and creates a socket where an X client connects etc.
> 
> Sincerely need your help. Thanks and sorry for the trouble.
> 
> Bye for now
> 
> On Tue, Jun 7, 2011 at 4:08 PM, Aris Adamantiadis <aris@xxxxxxxxxxxx> wrote:
>> Hi Jeetu,
>>
>> I did not have much time to read your email completely, but it seems in
>> first impression that server/client is sending garbage. Could you attach
>> the first hundreds lines of debugging output, especially the key exchange ?
>> Also, do you have an estimation of the number of bytes that have been
>> transmitted before the failure ? (i.e. does it approach gigabytes ?)
>>
>> Thanks,
>>
>> Aris
>>
>> Le 7/06/11 12:00, jeetu.golani@xxxxxxxxx a écrit :
>>> Hi guys,
>>>
>>> In continuation with my efforts to put together a libssh based server,
>>> I have had significant success and can say it is very impressive to
>>> see the effort you guys have put in the libssh library, thank you :)
>>>
>>> I could sincerely use some help though. All in all my server is
>>> behaving much more robust than it ever has. I have been testing with
>>> multiple X client applications being forwarded simultaneously and all
>>> in all it runs well. I had some previous issues I had mailed this list
>>> about (subject: multithreaded server issues) but an init of the buffer
>>> seems to have helped.
>>>
>>> I have noticed some behaviour I do not understand. Below is what the
>>> libssh log says when set to SSH_LOG_PACKET
>>>
>>> With multiple applications, after extensive use of the applications
>>> (for e.g. xeyes and xclock running) I have noticed that after sometime
>>> the applications are unable to refresh their window - there is no
>>> crash most of these times and if left alone maybe clock may eventually
>>> refresh part of the window etc. xeyes stops showing it's eyes moving
>>> around but still seems to be running - ssh client connected seems to
>>> show some activity too.
>>>
>>> The libssh log seems to suggest that there is packet corruption at
>>> this point. Two things stand out from the below log:
>>>
>>> I]
>>>
>>> [3] Decrypting 16 bytes
>>> [3] Packet size decrypted: 2754678753 (0xa4310fe1)
>>> [1] Error : read_packet(): Packet len too high(2754678753 a4310fe1)
>>>
>>> II]
>>> [3] Decrypting 96 bytes
>>> [1] Error : HMAC error
>>>
>>> Pls note this log is an excerpt of a long log taken once the strange
>>> behaviour has manifested.
>>>
>>> What is a HMAC error? can someone pls shed light on what could be
>>> causing the above?
>>>
>>> Thanks,
>>> Jeetu
>>>
>>>
>>> [3] Type 94
>>> [3] Dispatching handler for packet type 94
>>> [2] Channel receiving 32 bytes data in 0 (local win=72640 remote win=2095160)
>>> [1] placing 32 bytes into channel buffer (stderr=0)
>>> [2] Channel windows are now (local win=72608 remote win=2095160)
>>> [3] Decrypting 16 bytes
>>> [3] Packet size decrypted: 60 (0x3c)
>>> [3] Read a 60 bytes packet
>>> [3] Decrypting 48 bytes
>>> [3] 18 bytes padding, 59 bytes left in buffer
>>> [3] After padding, 41 bytes left in buffer
>>> [3] Final size 41
>>> [3] Type 94
>>> [3] Dispatching handler for packet type 94
>>> [2] Channel receiving 32 bytes data in 0 (local win=72608 remote win=2095160)
>>> [1] placing 32 bytes into channel buffer (stderr=0)
>>> [2] Channel windows are now (local win=72576 remote win=2095160)
>>> [3] Decrypting 16 bytes
>>> [3] Decrypting 16 bytes
>>> [3] Packet size decrypted: 2754678753 (0xa4310fe1)
>>> [1] Error : read_packet(): Packet len too high(2754678753 a4310fe1)
>>> [3] Packet size decrypted: 92 (0x5c)
>>> [3] Read a 92 bytes packet
>>> [3] Decrypting 96 bytes
>>> [1] Error : HMAC error
>>> [3] Writing on the wire a packet having 1993 bytes before
>>> [3] 1993 bytes after comp + 18 padding bytes = 2012 bytes packet
>>> [3] Encrypting packet with seq num: 36518, len: 2016
>>> [3] Enabling POLLOUT for socket
>>> [1] channel_write wrote 1984 bytes
>>> [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: 36519, len: 32
>>> [3] Enabling POLLOUT for socket
>>> [1] channel_write wrote 8 bytes
>>> [3] Read a 92 bytes packet
>>> [3] Decrypting 176 bytes
>>> [1] Error : HMAC error
>>> [3] Read a 92 bytes packet
>>> [3] Decrypting 256 bytes
>>> [1] Error : HMAC error
>>> [3] Read a 92 bytes packet
>>> [3] Decrypting 336 bytes
>>> [1] Error : HMAC error
>>> [3] Read a 92 bytes packet
>>> [3] Decrypting 416 bytes
>>> [1] Error : HMAC error
>>> [3] Read a 92 bytes packet
>>> [3] Decrypting 496 bytes
>>> [1] Error : HMAC error
>>> [3] Read a 92 bytes packet
>>> [3] Decrypting 576 bytes
>>> [1] Error : HMAC error
>>> [3] Read a 92 bytes packet
>>> [3] Decrypting 656 bytes
>>> [1] Error : HMAC error
>>> [3] Read a 92 bytes packet
>>> [3] Decrypting 736 bytes
>>> [1] Error : HMAC error
>>> [3] Read a 92 bytes packet
>>> [3] Decrypting 816 bytes
>>> [1] Error : HMAC error
>>> [3] Read a 92 bytes packet
>>> [3] Decrypting 896 bytes
>>> [1] Error : HMAC error
>>> [3] Read a 92 bytes packet
>>> [3] Decrypting 976 bytes
>>> [1] Error : HMAC error
>>> [3] Read a 92 bytes packet
>>> [3] Decrypting 1056 bytes
>>> [1] Error : HMAC error
>>> [3] Read a 92 bytes packet
>>> [3] Decrypting 1136 bytes
>>> [1] Error : HMAC error
>>> [3] Read a 92 bytes packet
>>> [3] Decrypting 1216 bytes
>>> [1] Error : HMAC error
>>> [3] Read a 92 bytes packet
>>> [3] Decrypting 1296 bytes
>>> [1] Error : HMAC error
>>> [3] Read a 92 bytes packet
>>> [3] Decrypting 1376 bytes
>>> [1] Error : HMAC error
>>> [3] Writing on the wire a packet having 8605 bytes before
>>> [3] 8605 bytes after comp + 14 padding bytes = 8620 bytes packet
>>> [3] Encrypting packet with seq num: 885, len: 8624
>>> [3] Enabling POLLOUT for socket
>>> [1] channel_write wrote 8596 bytes
>>> [3] Writing on the wire a packet having 8605 bytes before
>>> [3] 8605 bytes after comp + 14 padding bytes = 8620 bytes packet
>>> [3] Encrypting packet with seq num: 886, len: 8624
>>> [3] Enabling POLLOUT for socket
>>> [1] channel_write wrote 8596 bytes
>>> [3] Decrypting 16 bytes
>>> [3] Packet size decrypted: 3661937450 (0xda44bb2a)
>>> [1] Error : read_packet(): Packet len too high(3661937450 da44bb2a)
>>>
>>
>