Just to expand on what Mark has said, you can block all ports other than 25 from reaching port 25 on your mail server, remembering that if you are doing external DNS lookups you will need to open up DNS to DNS as well. But a smart telnet or low level packet program like Mudge's great netcat can easily fake its sending port number to bypass this. But it is still worthwhile as it will slow down the spammer scanners looking for open relays. Jamie. -----Original Message----- From: Mark Fugatt [mailto:mark@xxxxxxxxx] Sent: Saturday, 12 April 2003 12:11 AM To: [ExchangeList] Subject: [exchangelist] RE:Prevent Telnet to port 25 http://www.MSExchange.org/ I think they were looking at a way to stop people from using telnet to connect to port 25, and the only way to do that is to block port 25 and then you will not receive any mail from the outside world. Mark Fugatt MCT, MCSE, Microsoft Exchange MVP Pentech Office Solutions Inc Tel: 585 586 3890 Fax: 585 249 0316 www.4mcts.com <http://www.4mcts.com/> www.exchangetrainer.com <http://www.exchangetrainer.com/> _____ From: Joshua M. Etterman [mailto:jetterman@xxxxxxxxxxxxxxxxxxxxxxxxxxxx] Sent: Friday, April 11, 2003 10:39 AM To: [ExchangeList] http://www.MSExchange.org/ I don't quite remember how I did it, but you can't telnet into my exchange server (Ex2k + Win2kAdv + latest SP's) I think I went ahead and disabled telnet ability within Win2k. Are you talking about a non-telnet port? -- Joshua Etterman Complete College Solutions 513 W. Chocolate Ave. Hershey, PA 17033 Phone: (717) 508-2000 Fax: (717) 508-2001 E-mail: jetterman@xxxxxxxxxxxxxxxxxxxxxxxxxxxx -----Original Message----- From: Jamie A. Byrnes [mailto:jabyrnes@xxxxxxxxxxxxxxxxx] Sent: Friday, April 11, 2003 1:56 AM To: [ExchangeList] Subject: [exchangelist] RE:Prevent Telnet to port 25 The short answer is no. The longer answer is that you can set firewall rules to try to do this, but it is simple to get around. But the question is what are you trying to achieve? Jamie. -----Original Message----- From: Meral KESKINER [mailto:MeralK@xxxxxxxxxxxx] Sent: Friday, 11 April 2003 3:19 PM To: [ExchangeList] Subject: [exchangelist] Prevent Telnet to port 25 http://www.MSExchange.org/ Hi all, Is there a way to prevent telnet to my mail server? 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