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The Anti-SPAM service from Forskningsnettet - What is new about it?. TF-MSP meeting 4/2-2010 Martin Bech, UNI-C martin.bech@uni-c.dk. Fighting SPAM. A well-known problem Well-known solutions We all deal with spam Lots of home-built solutions Even more commercial services
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The Anti-SPAM service fromForskningsnettet- What is new about it? TF-MSP meeting 4/2-2010 Martin Bech, UNI-Cmartin.bech@uni-c.dk
Fighting SPAM • A well-known problem • Well-known solutions • We all deal with spam • Lots of home-built solutions • Even more commercial services Is there anything more for us as an NREN to do in this field?
Motivation for a common Anti-spam service • All universities are centralizing mail handling • All Universities are using considerable resources fighting spam • Maybe some kind of economy of scale may be achieved • And we may even have a few new ideas to make the whole service better and innovative…
The basic idea • Make the storage of spam mail the sender’s problem • While still preserving the benefits of having received the mails
RFC 2821 • SMTP client required to wait 10 minutes before timeout for DATA completion • After we have received the final “.” in the mail we scan it while keeping the connection open. • If scanning is succesful, we return the “250 OK” message otherwise the “550” message is issued • Our “550” message contains a URL that a “human” sender may use to push his email through
Standard reception flow SenderMTA Open TCP connection HELO local.domainMAIL FROM: mail@sendRCPT TO: mail@rec.dk DATASubject: bla bla More bla bla • In a blocking list? Greylisting No Bayesian filtering Yes …and whatever And give the mailthe standard filter treatment Virus scan Immediately reject mail: 550 Mail delivery rejected Immediately accept mail: 250 Message accepted for delivery Standard delivery Non-delivery mail to “sender”
Our approach Greylisting SenderMTA Open TCP connection HELO local.domainMAIL FROM: mail@sendRCPT TO: mail@rec.dk DATASubject: bla bla More bla bla • In a blocking list? Apply filtering while TCP connection from MTA open Bayesian filtering …and whatever Virus scan No Reject mail: 550 Mail delivery rejected Yes Immediately accept mail: 250 Message accepted for delivery Standard delivery
Advantages in our approach • It is the obligation of the sender to store the rejected mail • We don’t issue any non-delivery messages – they are the obligation of the sending MTA • Blocked and rejected mails may still be stored as desired by the user
Ability to rescue all important mails from deletion • Honest (or at least human) senders may push their mails through – provided they don’t contain virus • Users may rescue rejected mails because we can configure the system to keep a copy even when it is the responsibility of the sender to store the rejected mail • For instance: You want a mail from a robot whose MTA is on a blocking list
Several ways of recipient validation • LDAP • Radius • AD • “SMTP Interruptus”which means sending RCTP To: userto the mail-server and breaking the connection
Anti-SPAM production configuration This figure is not very fancy, but the aim is to transmit the message that wehave designed this with scalability in mind
Would a similar service be relevant in your NREN? • A tremendous interest from the users • All built using open-source components • No licences – only costs are our developers and the operations of the servers • We could help you build a similar setup – call me! martin.bech@uni-c.dk