[NBLUG/talk] Is someone trying to DDOS my email server?

Linford Mark mlinford at santarosa.edu
Thu Sep 22 11:13:42 PDT 2005


Hey, everyone:

I've been noticing some strange behavior on one of our mail servers, and it's starting to make me feel paranoid. For at least the past month or so, we've been getting email messages to an inactive account, followed by four random letters (user_accountxxxx@, user_accountyyyy@, etc.) What's strange is that each individual message is coming from a different server, and it's increasing. Last night, I received about 200 different attempts, all from different servers, and relatively evenly spread out. Should I be worried? Might someone be practicing a DDOS on me?

On a related note, is it possible with Sendmail to block certain addresses based on a wildcard (user_accountxxxx@ 550 REJECT, or something similar)? Any advice would be appreciated. Thanks!

Mark



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