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From Ken Lin <kennethlin2...@yahoo.com>
Subject Re: james SMTP authentication enforcement
Date Fri, 10 Mar 2006 08:46:33 GMT
 Can you clarify what you mean?

Norman Maurer <nm@byteaction.de> wrote: It would not make any sence if the whould not
accept the email..

Am Donnerstag, den 09.03.2006, 14:45 -0800 schrieb Ken Lin:
> 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  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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