I was thinking about this and what on the server side sets up the client virtual terminal( the IAC- will do, wont do, suppres go ahead etc.)? in.telnetd won't answer the call as the destination port is 25? --- Bill Royds <[EMAIL PROTECTED]> wrote: > Several firewalls support separating this (Raptor, > Cisco PIX, Gauntlet), but all the spammer/intruder > needs to do is use a client that doesn't send telnet > options such as the Solaris mconnect command. So the > trick of blocking clients that send telnet options > doesn't really work. > SMTP uses TCP port 25. You can't block 25/tcp > without also blocking SMTP, although you can > restrict it to SMTP only. > > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED]]On Behalf Of > Pascal C. Kocher > Sent: Thu April 25 2002 21:21 > To: Chris Lee; [EMAIL PROTECTED] > Subject: RE: blocking telnet to port 25 > > > Hello Chris > > > Sayed Peerzade wrote: > > > > > Hello, > > > > > > I'm systems engineer in an ISP handling mail > servers, i also handle > > > checkpoint. > > > pls tell me how to block telnet to port 25, > keeping normal telnet to > > > perform normally on mail server (netscape > messaging server > > running on > > > solaris OS)) > > > u can tell me method to block either in > checkpoint or on mail server > > > itself. > > > Thanks and regards. > > > > > > Sayed K.Peerzade. > > > > From: Chris Lee [mailto:[EMAIL PROTECTED]] > > > > If you want mail to through, you can't. > > > > Chris > > This is wrong. You are still able to get mail > through port 25 and not > allowing telnet (at least telnet clients) to connect > to the mailserver > over this port. Telnet sends options upon connection > (link Terminal > Type) which a regular SMTP Connection would not > send. Based on this you > could filter out telnet connections. Althoug I don't > know of any > firewall product which supports this. > > Best regards, > Pascal. > > _______________________________________________ > Firewalls mailing list > [EMAIL PROTECTED] > For Account Management (unsubscribe, get/change > password, etc) Please go to: > http://lists.gnac.net/mailman/listinfo/firewalls
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