[paramiko] Client generates bad MACs

[Dan Armak]

Hello,

I'm using paramiko to write simple a SFTP client and server pair to talk to 
each other.

When run on Gentoo everything works. When the client is run on Ubuntu, it 
sometimes apparently sends invalid SSH packet HMACs. Server trace:

DEBUG paramiko.transport.1.sftp Thread-2: Request: write
ERROR paramiko.transport Thread-1: Exception: Mismatched MAC
ERROR paramiko.transport Thread-1: Traceback (most recent call last):
ERROR paramiko.transport Thread-1:   
File "/home/danarmak/projects/castd/paramiko/transport.py", line 1335, in run
ERROR paramiko.transport Thread-1:     ptype, m = 
self.packetizer.read_message()
ERROR paramiko.transport Thread-1:   
File "/home/danarmak/projects/castd/paramiko/packet.py", line 330, in 
read_message
ERROR paramiko.transport Thread-1:     raise SSHException('Mismatched MAC')
ERROR paramiko.transport Thread-1: SSHException: Mismatched MAC
ERROR paramiko.transport Thread-1:
DEBUG paramiko.transport.1.sftp Thread-2: EOF -- end of session

Where Thread-1 is the main server thread:
DEBUG paramiko.transport Thread-1: starting thread (server mode): 0x48E71110L

And Thread-2 is the thread receiving the upload:
DEBUG paramiko.transport Thread-2: Starting handler for subsystem sftp

(My own threads set their names explicitly, so they don't increment the thread 
naming count.)

If I use an openssh server the same happens:

Oct  8 00:20:39 claw sshd[29809]: Disconnecting: Corrupted MAC on input.

This only happens when the client runs on Ubuntu. If the client is on Gentoo 
(and the server either on Gentoo or on Ubuntu) everything works.

I'm using paramiko 1.6.2 on both systems (the ubuntu paramiko package is only 
at 1.5.2, which exhibits the same behavior). Other relevant packages have the 
same (upstream) versions on both systems: python 2.4.3, pycrypto 2.0.1. Both 
systems have all installed packages at the latest available versions.

What might be causing this? How can I debug it?

TIA,

-- 
Dan Armak
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 827 bytes
Desc: not available
Url : http://www.lag.net/pipermail/paramiko/attachments/20061008/c05e8d67/attachment.pgp