RE: [cobalt-users] POP3 Scanning

["Dan Kriwitsky" <list3@xxxxxxxxxxxxxxxxxxxx>]

>   Recently we have seen an increase in POP3 scanning.  The 
> robot will open a POP3 connection and try to login as some 
> user.  When the server says, "No such user here", it 
> continues until it finds a valid email account.  I call this 
> trolling for valid mailboxes.  I'm sure there is a more 
> techie term for it.

It's called a dictionary attack.

> 
> Anyway, has anyone found a good, solid way to prevent these 
> people from doing this?  Even if we could prevent the "No 
> such user" response for invalid mailboxes, it would at least 
> render their activities as useless.

Looks like some people have come up with methods to block this.

http://www.google.com/search?sourceid=navclient&q=Sendmail+dictionary+at
tack+%22No+such+user%22
-- 
C2003 Dan Kriwitsky

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