Antispam methods

De gacq wiki

Contenido

Greylists

postgrey

Install

apt-get install postgrey
netstat -anp | grep 60000
 tcp        0      0 127.0.0.1:60000         0.0.0.0:*               LISTEN     18478/postgrey.pid

In /etc/postfix/main.cf add to "smtpd_recipient_restrictions ="

check_policy_service inet:127.0.0.1:60000

Restart postfix:

/etc/init.d/postfix restart

Administration

Lists the automatically whitelisted servers:

perl /usr/share/doc/postgrey/postgrey_clients_dump

Mail Analysis

SpamAssassin

Blacklist

/etc/postfix/main.cf

  reject_rbl_client bl.spamcop.net,
  reject_rbl_client relays.ordb.org,
  reject_rbl_client sbl-xbl.spamhaus.org,

SPF Filtering

SPF stands for Sender Policy Framework. It's a way for your server to verify if a connecting client is supposed to be sending mail for the domain it claims to be sending mail for. It works by checking a special DNS record that domain owners create for this specific purpose. For more info on the Sender Policy Framework check out the Openspf site

DomainKeys

TMDA

Significantly reduce the amount of spam

  • whitelists: accept mail from known, trusted senders.
  • blacklists: refuse mail from undesired senders.
  • challenge/response: allows unknown senders which aren't on the whitelist or blacklist the chance to confirm that their message is legitimate (non-spam).
  • tagged addresses: special-purpose e-mail addresses such as time-dependent addresses, or addresses which only accept certain kinds of communication. These increase the transparency of TMDA for unknown senders by allowing them to safely circumvent the challenge/response system.

This methodology has the advantage of being very selective about what it allows in, while at the same time permitting legitimate, but previously unknown senders to reach you.

References

Herramientas personales