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From Ken Lin <kennethlin2...@yahoo.com>
Subject Re: james SMTP authentication enforcement
Date Thu, 09 Mar 2006 22:45:48 GMT
Stefano:
    
    Great to hear from your experience. It sounds a lot of effort to become a committer.
  
    Here is the open relay testing site that I used:
    http://www.abuse.net/relay.html
  This appears to be pretty popular as it showed up as the top link on  google for "mail relay
test". My james server failed the test case I  mentioned earlier in email (spoofing ...@xyz.com
to ...@xyz.com).
  
  I went ahead and  tested a few other ISP and corporation's email. It seems when SMTP  authentication
is not established, many directly reject any mail with  sender containing the designated domain
name. Here are the servers I  tested that rejected all spoof:
    
    Mail ISP:
    Gmail: gsmtp183.google.com
  Hotmail: mf4100beta1.solinus.com
    
    Corporation email:
    Google.com: smtp1.google.com
    Amazon.com: smtp-fw-0101.amazon.com
    Microsoft.com: mailb.microsoft.com

  The test on Yahoo seems to have failed that it accepts a "fake" email  from ...@yahoo.com
to ...@yahoo.com. However, it is possible that yahoo  "drops" spoofed mails in spooling queue
(like using the configuration  similar to what you posted earlier). I need to confirm this
later. (I  can't do the spoofing testing at work at the moment because our  corporate firewall
blocks all outgoing port 25 access)
  
  Just to make sure that the code change won't violate the RFC, can you  let me know the RFC
number and section number that mandates any email  from @xyz.com can be sent to postmaster@xyz.com
without SMTP  authentication? I looked at the following two RFCs from the IETF site  and couldn't
find this mandate:
  SMTP RFC (821): http://www.ietf.org/rfc/rfc0821.txt
  SMTP authentication RFC (2554): http://www.ietf.org/rfc/rfc2554.txt
  
  Ken
  
Stefano Bagnara <apache@bago.org> wrote:  Ken Lin wrote:
>  Maybe this method of "spoofing" users has been overlooked. Even if  James has SMTP turned
on, I can impersonate any user of the server and  send another user an email without any authentication.
In a way, it  seems to be a security hole open by default unless people apply your  section
of configuration.

You, anyway, will never stop people from using your email as sender 
address and send messages around the world. There are solutions to stop 
this behaviour (e.g. SPF) but not supported by all the SMTP server so I 
don't think that we can consider this thing a "security hole" in james.
I'm not 100% sure, but I bet that most mail servers will not block 
messages with a "from:" containing a local domain to be relayd (even 
with authentication on).

>  Well we check for recipient address in the first place. This checking  is not explicitly
mentioned in the RFC either, but is just implicitly  allowed. By the same token, checking
the sender address should be  allowed too.

You'd be not RFC compliant because you MUST accept a mail "from: 
xxx@xyz.com" "to: postmaster@xyz.com" even without authentication.

I think that this is not specified in the RFC and is not even common 
practice for SMTP servers and we should not make it the default.
Btw, if you want to write a patch to provide an option to enable this 
behaviour I'll try to review it.

>  What do you think? Actually, are you a software developer on the James team? How do
I become one?

I'm a James committer. I've been "proposed" by other James committers 
one year ago after many months of support here in the list and after 
having submitted many patches to the issue tracker.

Stefano


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