On Thu, 2 May 2002, V=EB=E9r=EAsh Kh=E5n=F6rk=E3r wrote:

>
> I had made EHLO mandatory in the XMail server by
> commenting the code which acknowledges the "HELO"
> command,hence the only command that is accepeted by
> the email server is "EHLO". And later when the server
> was built I tested it again, and found that if the
> authentication is failed stil the server will allow
> the mail delivery. In my case the email server has no
> chance accepting mail from another email server and
> hence there is no need for allowing "HELO" command,
> users can ofcourse use "EHLO". However while testing
> the security, I found this security hole. I did change
> the code a bit by rejecting the session as soon as the
> authentication fails. However I thought I should
> inform Davide abt. it. It could be a potential loop
> hole. Try it out yourself,
>
> *) EHLO somedomain
> *) MAIL FROM: <[EMAIL PROTECTED]>
> *) RCPT To: <[EMAIL PROTECTED]>
>
> Now the mail server should object at the second
> command itself, however that doesnt happen either.
> And the message gets delivered, its the same as mail
> delivery without authentication with EHLO.

Your approach, besides being broken, breaks quite a few RFCs and does not
fix any problem. Authentication *add* privileges to a default *init* state
of the server. If your default/base state is *open* then you've to fix
your configuration not break the code.



- Davide


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