gmane.mail.popa3d.user

Sean Kelly | 5 May 06:28

popa3d logging under xinetd

Hello,

I’ve been hacking around in the popa3d code trying to figure out how it works so that I might be able to get it to log/record the user’s IP address for use with pop-before-send SMTP access control. I just discovered that the whole “channel” construct is pulling user session data from a pipe rather than a socket as I was expecting when running under xinetd. As far as I can tell standalone mode uses a regular listening socket and obtaining the IP address of the user from the sockaddr structs is a simple matter in that mode. But I’m at a loss for what to do under xinetd as I really don’t understand how xinetd handles connections and such. Is there anyone who might be able to lend a little guidance here?

I’m specifically poking around in the do_pop_session(0 function of pop_root.c.

Thank you,

Sean Kelly - The “other half” of Keen Kelly

sean-JVZV1WlgsJHqlBn2x/YWAg@public.gmane.org

http://www.keenkelly.com/

Office: (408) 578-8888

P.O. Box 18202; San Jose, Ca; 95158

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Solar Designer | 5 May 19:09

Re: popa3d logging under xinetd

Sean,

On Wed, May 04, 2005 at 09:29:10PM -0700, Sean Kelly wrote:
> I've been hacking around in the popa3d code trying to figure out how it
> works so that I might be able to get it to log/record the user's IP
> address for use with pop-before-send SMTP access control. I just
> discovered that the whole "channel" construct is pulling user session
> data from a pipe rather than a socket as I was expecting when running
> under xinetd.

The "channel" stuff is being used to implement privilege separation.

There is a socket, it is just not seen explicitly since it's provided
by the *inetd.  The socket is on fd 0/1/2 (stdin/out/err) at program
startup.  You can invoke getpeername(2) on any of these fd's to find
out the remote client's IP address.  The same would _also_ work when
running standalone.

Some software also sets the REMOTE_HOST environment variable.  You
can have your code fallback to uses of REMOTE_HOST when either the
getpeername(2) call fails or the connection appears to come from
localhost.  This will let you do POP-before-SMTP even for SSL'ed
connections with xinetd and stunnel.

BTW, contrib/popa3d-0.6.2-whoson-1.diff.gz already implements just
that, so you might not even need to develop the patch on your own.

--

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Alexander Peslyak <solar at openwall.com>
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