FW: PCI Compliance
in [Postfix]
|
Prev: PCI Compliance
Next: MDN and mupliple recipients
From: "Jonathan Tripathy" on 18 Mar 2010 09:53 > Any ideas on how to set up an "SMTP Proxy Server" to attain PCI Compliance? > I literally need postfix to just pass through mail to our ISP's smtp server. > We would then set outlook to use this local smtp proxy server. I work for a hosting company, we find it's usually an iterative process. This particular question hasn't come up yet (for an SMTP server), but it'd go something like this: 1. Customer needs certification for a contract, so they hire a company to perform a PCI audit scan 2. The scan finds "problems", so they come to us with the report, which says how to fix the problems 3. We read the report, and find things like "server exposes its hostname in the greeting banner", or "server appears to allow the use of the VRFY command". 4. We sigh, then go through the motions to "fix" the "problems". Sometimes the problem descriptions are hopelessly vague, like "this system /may/ be vulnerable to a known buffer overflow", and the system is fully patched and up to date. Can't do much about these, so we tell our customer to take it up with the auditor. 5. Rinse and repeat until all perceived problems are fixed, and/or the customer stops hassling. :) So, my apologies that this doesn't really answer your question. If you need compliance certification then you'll need an audit anyway, at which point you find out what the requirements are. It's not trivial to simply look up the requirements, because... PCI-DSS doesn't actually cover specific implementation details. It's sufficiently vague (probably by design) so that'll it'll stay relevant as time goes on, and so that current best practices are followed. Have a look at the PCI spec, it's only half a meg in PDF: https://www.pcisecuritystandards.org/security_standards/pci_dss.shtml Page 4 is a summary of what you really need to know. Page 6 mentions segmentation to reduce the scope of what needs to comply - this is your best bet (if feasible) to sidestep compliance for your mail server. If you enjoy some light humour, we've elaborated on the aforementioned process a little: http://www.anchor.com.au/blog/2008/12/saas-security-scanning-as-a-service/ > I'm not entirly sure if a "relay" server is good here, as how would that > handle bounced mail?? Indeed, you want to avoid more relays if you can, both for administration and compliance reasons. Bounced mail isn't so bad, so long as there's a return path to the sender's mailbox. A naive example of how this might work: Sending: outlook -> workstation -> PCI-compliant relay -> ISP's SMTP server -> recipient *it bounces because the recipient's mailbox is full* Recipient -> MX lookup -> Your incoming SMTP server (maybe this is at your ISP) -> The sender's mailbox -> Picked up by outlook ------------------------------------------------------------------------ Thanks for the long reply, it's appreciated. But.. The network I am dealing with is very small and simple. I am aware about the PCI scans, and I have done some in the past. Thankfully, regarding this case, I only need an "SMTP Proxy" to be placed in the DMZ, as computers inside the CDE (Cardholder Data Environment) arn't allowed to connect to hosts on the internet. LIterally, all I need to do, is place an HTTP proxy (Squid), an SMTP Proxy, and a POP3 Proxy in the DMZ, and that's me. Of course, block all ports into and out of the CDE, except allow CDE to connect to SMTP proxy, POP3 Proxy and Squid Proxy. Now, of course, there are other things in the PCI DSS, such as policies and processes, however these are out of my scope, as I'm just an external I.T. guy. BTW, the machines in the CDE will all have anti-virus and automatic updates enabled. So, back to postfix, can it do such a thing? Act as a "proxy" and not a "store and forward relay"
From: Reinaldo de Carvalho on 18 Mar 2010 10:00 On Thu, Mar 18, 2010 at 10:53 AM, Jonathan Tripathy <jonnyt(a)abpni.co.uk> wrote: > > BTW, the machines in the CDE will all have anti-virus and automatic updates > enabled. > > So, back to postfix, can it do such a thing? Act as a "proxy" and not a > "store and forward relay" > > > In theory you can to use 'smtpd_proxy_filter'. http://www.postfix.org/postconf.5.html#smtpd_proxy_filter -- Reinaldo de Carvalho http://korreio.sf.net http://python-cyrus.sf.net "Don't try to adapt the software to the way you work, but rather yourself to the way the software works" (myself)
From: Mark Goodge on 18 Mar 2010 10:10 On 18/03/2010 13:53, Jonathan Tripathy wrote: > > So, back to postfix, can it do such a thing? Act as a "proxy" and not a > "store and forward relay" In SMTP terms, a proxy is effectively the same thing as a store-and-forward relay. But yes, Postfix will do this very well. For inbound mail, you can set up a transport map so that all incoming mail is forward to the "true" mail server inside the CDE. Use recipient address verification to make sure that you don't become a backscatter source, and it will do exactly what you want with minimal hassle. For outbound mail, simply use the DMZ machine as a smarthost for any machine inside the CDE (including your Exchange server if appropriate). Mark
From: Wietse Venema on 18 Mar 2010 10:11 Jonathan Tripathy: > So, back to postfix, can it do such a thing? Act as a "proxy" and > not a "store and forward relay" http://www.postfix.org/SMTPD_PROXY_README.html Someone will still have to monitor the logfile, and deal with "postmaster notification" email depending on how the notify_classes parameter is configured. Wietse
From: Victor Duchovni on 18 Mar 2010 12:03
On Thu, Mar 18, 2010 at 11:00:14AM -0300, Reinaldo de Carvalho wrote: > On Thu, Mar 18, 2010 at 10:53 AM, Jonathan Tripathy <jonnyt(a)abpni.co.uk> wrote: > > > > BTW, the machines in the CDE will all have anti-virus and automatic updates > > enabled. > > > > So, back to postfix, can it do such a thing? Act as a "proxy" and not a > > "store and forward relay" > > > > > > > > In theory you can to use 'smtpd_proxy_filter'. > > http://www.postfix.org/postconf.5.html#smtpd_proxy_filter It works in practice. A few Postfix TLS proxies have been terminating TLS connections, making access control decisions and forwarding unencrypted SMTP to a non-Postfix server for many years now. These systems only run "smtpd" as a proxy, and use various internal services, but otherwise there is no message processing. There is no logging from cleanup(8), qmgr(8), smtp(8), ... connectins come in and then they go out. Mail is never queued on the TLS proxy. -- Viktor. P.S. Morgan Stanley is looking for a New York City based, Senior Unix system/email administrator to architect and sustain our perimeter email environment. If you are interested, please drop me a note. |