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Refuse any command when telnet to port 25

Posted on 2002-06-13
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Last Modified: 2006-11-17
how can I protect my mail server such as MS exchange from anyone who telnet to port 25 and then use any command such as VRFY to verify users on my mail server ??
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Question by:sirator
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rid earned 200 total points
ID: 7076095
The server software may have (should indeed have) an option to discard/deny VRFY commands. Look for this.

Regards
/RID
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by:samri
ID: 7084980
There is some information found on this link.

Scroll to the middle of the page.

http://216.239.33.100/search?q=cache:gSTBYPODqkgC:www.ima.com/pdf/ienews/vol4no6.pdf+disable+vrfy+ms+exchange&hl=en&ie=UTF8

I hope this helps.
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Author Comment

by:sirator
ID: 7101444
Thanks , rid,but I see most of mail servers are already tuned for not permitting to use VRFY, Is it right ?
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Expert Comment

by:rid
ID: 7102007
I think most defaults to reject VRFY commands, yes.

Rejecting ALL commands if they come from a telnet session may be another matter. Since SMTP commands are a bit on the simplistic side, doing them by telnet isn't too complicated. You'd have to reject telnet sessions only, and not SMTP session. Perhaps some firewall setting could do this, but what is to gain from that?

Regards
/RID
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