This presentation was given at Python North West. It explains a complete Kamaelia application for greylisting which was written specifically to eliminate my personal spam problem. It walks through the code as well (though that's best looked at with the code side by side!)

1. Relevant disclosure? - Kamaelia came out of my day work @ BBC Research - Kamaelia grey came out of my personal frustration, and has nothing to do with the BBC :-) Michael Sparks , [email_address] Kamaelia Grey

2. Drastic Spam reduction through Greylisting Greylisting made easy through natural concurrency Natural concurrency made easy through Kamaelia ... since that's what Kamaelia is for Kamaelia Grey

10. Where?

11. Here!

13. Mail serving UNTRUSTED INTERNET

14. Mail serving UNTRUSTED INTERNET MAIL SERVER 25

15. Mail serving UNTRUSTED INTERNET MAIL SERVER 25

16. Mail serving UNTRUSTED INTERNET MAIL SERVER 25

17. Greylisting UNTRUSTED INTERNET MAIL SERVER 8025

18. Greylisting UNTRUSTED INTERNET MAIL SERVER 8025 Kam Grey 25

19. Greylisting UNTRUSTED INTERNET MAIL SERVER 8025 Kam Grey 25

21. Basic config port = 25 servername = mail.cerenity.org serverid = Kamaelia-SMTP 1.0 smtp_ip = 192.168.2.9 smtp_port = 8025 inactivity_timeout = 60 greylist_log = /var/log/greylist.log greylist_debuglog = /var/log/greylist-debug.log attempters_db = /var/spool/attempters.dbm greylisted_db = /var/spool/greylisted.dbm

22. Local config allowed_senders: 127.0.0.1 allowed_sender_nets: 192.168.2 allowed_domains: private.thwackety.com thwackety.com thwackety.net yeoldeclue.com michaelsparks.info lansdowneresidents.org polinasparks.com pixienest.com kamaelia.org owiki.org cerenity.org

23. Exceptions # Standard triples which always allows delivery to domains we consider # accepting for. # # Format: # IP address, mail-from id, recipient id # whitelisted_triples: 213.38.186.202 <post@mx1.redcats.co.uk> <polina@thwackety.com>

24. Exceptions # Some non-standard triples for which we always allow delivery # to domains we consider accepting for. # Format: # claimed sender name, IP prefix, recipient # whitelisted_nonstandard_triples: listmail.artsfb.org.uk 62.73.155.19 <polina@thwackety.com> mx-out.facebook.com 204.15.20 <ms@cerenity.org> mx-out.facebook.com 204.15.20 <polina@cerenity.org> fallbackmx-out.facebook.com 204.15.20 <ms@cerenity.org> fallbackmx-out.facebook.com 204.15.20 <polina@cerenity.org>

25. Logging? Standard log: /var/log/greylist.log 20071106172215.940 | dsl88.241-20782.ttnet.net.tr | 88.241.81.46 | <linhotepmet@hotep.de> | <ms@cerenity.org> | DEFERRED | 20071106172231.269 | dsl88.241-20782.ttnet.net.tr | 88.241.81.46 | <linkinosoftmet@kinosoft.de> | <ms@cerenity.org> | DEFERRED | 20071106172238.610 | 34-148.privatnet.cz | 88.146.148.34 | <ggybaseh@walla.com> | <messages@cerenity.org> | DEFERRED | 20071106172244.333 | dsl88.241-20782.ttnet.net.tr | 88.241.81.46 | <linlinasolutionsmet@linasolutions.de> | <ms@cerenity.org> | DEFERRED | 20071106172247.885 | mta410.k.cheetahmail.com | 208.49.63.136 | <bo-b00hg7jaukqbyva8zuwb9b9y5ph44j@b.emails.dixons.co.uk> | <zathras-pcworld@thwackety.com> | ACCEPTED |

26. Logging? Debug log: /var/log/greylist.log 250 OK 250 ACCEPTED 451 4.7.1 Please try again later 220 mail.cerenity.org ESMTP Kamaelia-SMTP 1.0 Tue Nov 6 17:26:01 2007 500 Command Not Recognised 250 mail.cerenity.org Hello lse 89.252.24.7 250 OK Note – this is what's being sent over SMTP

27. But also... Debug log: /var/log/greylist-debug.log *debug* THREADS['Kamaelia.Chassis.Pipeline.Pipeline_7', 'Kamaelia.Internet.Selector.Selector_11', '__main__.GreylistServer_8', '__main__.PeriodicWakeup_5', '__main__.TCPS_10', '__main__.WakeableIntrospector_6'] Note – this says the current internal components running

28. Internals Debug log: /var/log/greylist-debug.log ['Kamaelia.Chassis.Pipeline.Pipeline_7', 'Kamaelia.Internet.Selector.Selector_11', '__main__.GreylistServer_8', '__main__.PeriodicWakeup_5', '__main__.TCPS_10', '__main__.WakeableIntrospector_6'] Note – this says the current internal components running

29. Internals Debug log: /var/log/greylist-debug.log Kamaelia.Internet.Selector.Selector_11 – wakes system on network events __main__.TCPS_10 – sits inside and handles listening for '__main__.GreylistServer_8 – A configured network server Kamaelia.Chassis.Pipeline.Pipeline_7 – For debugging '__main__.PeriodicWakeup_5 – For debugging '__main__.WakeableIntrospector_6 – For debugging Note – this says the current internal components running

30. No connection! TCPServer Greylist Server Selector

31. New connection! TCPServer Greylist Server Selector Connected Socket Adapter GreyListing Policy

32. More connections! TCPServer Greylist Server Selector Connected Socket Adapter GreyListing Policy Connected Socket Adapter GreyListing Policy Connected Socket Adapter GreyListing Policy Connected Socket Adapter GreyListing Policy

33. Accepted! GreyListing Policy TCPClient Connected Socket Adapter MAIL SERVER 8025

34. Rejected! Connected Socket Adapter GreyListing Policy

35. Greylisting GreyListing Policy Concrete Mail Handler Mail Handler

36. Internals The following pages are intended as a walk through of the key highlights of the code-base. It skips the body of the code since that's best looked at by scrolling through code and chatting rather than dumping into slides. In a presentation its easy to say this, and then after going through slides giving road pointers go through the code. Presentation files are a little more limited. The code referred to is here: http://tinyurl.com/2sbjxl

37. Internals class MailHandler(Axon.Component.component): logfile = &quot;greylist.log&quot; debuglogfile = &quot;greylist-debug.log&quot;

38. Internals class MailHandler(Axon.Component.component): def __init__(self,**argd): def logging_recv_connection(self): def getline(self): def handleCommand(self,command): def noteToLog(self, line): def noteToDebugLog(self, line): def netPrint(self, *args): def lastline(self): def main(self):

39. Internals class ConcreteMailHandler(MailHandler): Inboxes = { &quot;inbox&quot; : &quot;Data from the client connecting to the server comes in here&quot;, &quot;control&quot; : &quot;Shutdown & control messages regarding client side socket handling&quot;, &quot;tcp_inbox&quot; : &quot;This is where we get respones from the real SMTP server&quot;, &quot;tcp_control&quot; : &quot;This is where we get shutdown information from the real SMTP server&quot;, } Outboxes = { &quot;outbox&quot; : &quot;Data sent here goes back the the client connecting to the server&quot;, &quot;signal&quot; : &quot;Shutdown & control messages regarding client side socket handling&quot;, &quot;tcp_outbox&quot; : &quot;Data sent here is sent to the real SMTP server&quot;, &quot;tcp_signal&quot; : &quot;We send messages here to shutdown the connection to the real SMTP connection&quot;, } peer = &quot;*** UNDEFINED ***&quot; peerport = &quot;*** UNDEFINED ***&quot; local = &quot;*** UNDEFINED ***&quot; localport = &quot;*** UNDEFINED ***&quot; servername = &quot;Testing.server.local&quot; serverid = &quot;MPS SMTP 1.0&quot; smtp_ip = &quot;192.168.2.9&quot; smtp_port = 25

40. Internals class ConcreteMailHandler(MailHandler): def connectToRealSMTPServer(self): def __init__(self, **argv): def error(self, message): def RelayError(self): def handleConnect(self): def handleEhlo(self,command): def handleHelo(self,command): def handleHelp(self,command): def handleVrfy(self,command): def handleRset(self,command): def handleNoop(self,command): def handleMail(self,command): def handleRcpt(self,command): def handleData(self, command): def handleQuit(self,command): def shouldWeAcceptMail(self): return False # Default policy - don't accept any email def deferMail(self): def acceptMail(self): def getline_fromsmtpserver(self): def handleDisconnect(self):

41. Internals class GreyListingPolicy(ConcreteMailHandler): allowed_senders = [] allowed_sender_nets = [] allowed_domains = [ ]

42. Internals class GreyListingPolicy(ConcreteMailHandler): (continued) def shouldWeAcceptMail(self): def sentFromAllowedIPAddress(self): def sentFromAllowedNetwork(self): def sentToADomainWeForwardFor(self): def isGreylisted(self, recipient): def whiteListed(self, recipient): def logResult(self):

43. Internals class GreylistServer(MoreComplexServer): logfile = config[&quot;greylist_log&quot;] debuglogfile = config[&quot;greylist_debuglog&quot;] socketOptions=(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) port = config[&quot;port&quot;] class TCPS(TCPServer): CSA = NoActivityTimeout(ConnectedSocketAdapter, timeout=config[&quot;inactivity_timeout&quot;], debug=False) ....

44. Internals class GreylistServer(MoreComplexServer): (continued) # ... class protocol(GreyListingPolicy): servername = config[&quot;servername&quot;] serverid = config[&quot;serverid&quot;] smtp_ip = config[&quot;smtp_ip&quot;] smtp_port = config[&quot;smtp_port&quot;] allowed_senders = config[&quot;allowed_senders&quot;] allowed_sender_nets = config[&quot;allowed_sender_nets&quot;] allowed_domains = config[&quot;allowed_domains&quot;] whitelisted_triples = config[&quot;whitelisted_triples&quot;] whitelisted_nonstandard_triples = config[&quot;whitelisted_nonstandard_triples&quot;]

45. And that... Saves me having to wade through now literally tens of thousands of spams over the past two months: # grep DEFERRED /var/log/greylist.log |wc -l 73798

46. Time to write? 2 days start to finish including protocol Bug fixes ~1-2 days tops

47. Questions? Thank you :-) I hope it's useful to you :)