I meant to say that some scanning tools might give you funny results some 
times. I am wrong in saying that nmap would report that smtp was open, 
because nmap works differently for a TCP scan...


>From: "D H" <[EMAIL PROTECTED]>
>To: [EMAIL PROTECTED], [EMAIL PROTECTED]
>Subject: Re: [FW1] Rules cause services to be seen?
>Date: Tue, 01 Aug 2000 23:21:50 GMT
>
>
>It might be a problem with how the scanning tool determines if a port is
>"open".
>
>For example, here's part of the nmap man page:
>"UDP scans: This method is used to determine which UDP (User Datagram
>Protocol, RFC 768) ports are open on a host. The technique is to send 0 
>byte
>udp packets to each port on the target machine. If we receive an ICMP port
>unreachable message, then the port is closed. Otherwise we assume it is
>open."
>
>If your Firewall policy is dropping smpt packets, rather than rejecting
>"ICMP port unreachable" messages are not going to be sent, so the nmap 
>would
>report the port is "open".
>
>Hope this helps.
>-- DH
>
>
>
>>From: Tom Sevy <[EMAIL PROTECTED]>
>>To: "Check Point FW List (E-mail)"
>><[EMAIL PROTECTED]>
>>Subject: [FW1] Rules cause services to be seen?
>>Date: Tue, 1 Aug 2000 17:28:39 -0400
>>
>>
>>I added a rule to filter out (not allow) inbound email to a specific
>>address.
>>
>>Once I did this, and ran a port scan, smtp shows open on every IP address
>>that the FW is proxying for.  Is there a fix for this?
>>
>>I saw the same thing when I tried to create a client-auth rule to allow
>>outbound Telnet.  Telnet port showed up on a scan for every IP address 
>>that
>>the FW is proxying.
>>
>>
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