*ANY* firewall software should be able to handle this, usually by  
added the 'log' keyword to the line containing the interesting  
traffic.  A couple examples:

pf:

block in log quick on fxp0 proto {tcp} from any to self port {80,443}

ipfw:
ipfw add log all from any to $self 80, 443

HTH

Eric

On May 2, 2008, at 7:49 AM, Josh Welch wrote:

> Quoting Chris Niesen <chris.niesen at gmail.com>:
>
>> I am trying to setup a server/app that can log when a certain port  
>> has been
>> accessed on an inbound interface on my firewall.  I don't need the  
>> whole
>> contents of the packet, just the port number accessed (I have  
>> certain ports
>> to filter and define, i.e. ssh, http, https), the time and the  
>> date.  I also
>> want to have this dumped to a text file, with a preset size limit  
>> that will
>> automatically save to a new file once the threshold has been  
>> reached.  I
>> already have a port mirror setup on my core switch to dump all the  
>> traffic
>> there so I can see all of it, I just am having a log of trouble  
>> filtering
>> and logging exactly what I need with an app.  I have tried writing  
>> my own
>> custom snort rules, and dumping it to a file, but I can't seem to  
>> get that
>> right.  I also have written capture filters for wireshark; those  
>> pick up
>> only the packets I want, but, they log the whole packet, not just the
>> information I am looking for.  Does anyone on the list have any  
>> experience
>> with this type of thing?
>>
>>
>
> IPTables will do this, look into the LOG function. I would
> occasionally do this same thing for troubleshooting purposes.
>
> Josh
>
>
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-----
Eric F Crist
Secure Computing Networks