Re: How to block a ddos attack?
Zdravko Stoychev <[email protected]>
| Newsgroups | gmane.mail.qmail.ldap |
|---|---|
| Message-ID | <[email protected]> |
Hi! > It may help to block with blacklists (i.e. zen.spamhaus.org), > additionally it may help to block IPs without reverse DNS. > Using RBL check to using several of them to different blacklist DBs is a must nowadays. > I am not sure if this is really a DDoS, its sounds more like daily life > for any SMTP server these days. > Still it happens that a certain e-mail address is used in a huge spammers session, and it might happen for a period of several days this e-mail will receive unusual amount of bounces, fake e-mails and bogus responses (read from AV, AS software, etc.) So it's a kind of DDoS. Thus your server should be able to handle it = add more RAM, put better CPU and so on. > We currently have 3.7 percent of legitimate mail traffic on our servers. > 96.3 percent is junk. > Right, indeed! Same here. > The blacklists and reverse DNS checks let us drop 91.9 percent of the > connections before SMTP really starts. So our servers have to deal with > only 8% of the connections. Your mileage may vary. > This is good. But one should also use other techniques. Add SPF, DomainKeys, DKIM checks and enforce their policies. And the most important, which alone will fight about 70% of RBL-check missed e-mails, is the Graylisting technique. With all this implemented, your mailbox shall hit 2-3 SPAM e-mails per week. Not bad :) > Regards > > Alain Wolf Hope this helps, and regards! -- *Zdravko Stoychev* IT Administrator *MPS Ltd.* <http://www.mps.bg/> 63, Shipchenski Prohod bul. 10 floor, office 105 Sofia 1574 Bulgaria *Work:* 0035924911827 *Mobile:* 00359888243118 *Fax:* 0035929733836 *Email:* [email protected] <mailto:[email protected]> *IM:* 11693613 (AIM) *My Professional Profile <http://www.linkedin.com/in/zdravkos>* *My GnuPGP Public Key <http://keyserver.ubuntu.com:11371/pks/lookup?op=get&search=0x857DE27D2C64101C>* EC7E CA74 952D F343 2AAD 0F34 857D E27D 2C64 101C See who we know in common <http://www.linkedin.com/e/wwk/17665515/> Want a signature like this? <http://www.linkedin.com/e/sig/17665515/> "If someone is going down the wrong road, he doesn't need motivation to speed him up. What he needs is education to turn him around." - Jim Rohn This e-mail is intended only for the addressee(s) and may contain privileged and confidential information. It should not be disseminated, distributed, or copied. If you have received this e-mail message by mistake, please inform the sender, and delete it from your system.