On 29/08/2012 08:20, RUOFF, LARS (LARS) wrote:
Hi Mike,
No, if someone would be using a different port for email, then Wireshark will not decode it as SMTP or POP in the first place. (Because the dissection for these protocols is based on a port preference. Meaning that Wireshark will only decode the packets as POP/SMTP if the traffic goes over the well known port numbers for these protocols)
What you would need is some sort of heuristics that can identify POP/SMTP from the packet data itself, but i don' think Wireshark has that built in for the moment.
Otherwise, if your email is unencrypted, you might just as well want to filter on common plain-text email headers within the data portion of any TCP traffic.
regards,
Lars
As Lars says - (POP or SMTP) will just identify traffic on ports 25 and
110, in order to do further you need protocol inspection of all traffic.
Running snort over a RSPAN port of your internet VLAN might be able to
perform this kind of inspection for you... you would probably have to
write your own snort rule for this.
http://www.snort.org
I would like to monitor the email traffic in and out of our network to make sure that no one is using the incorrect ports. I need this information as I would like to setup a firewall rule that would only allow traffic to and from one specific server. I think I have found the answer to this question but so far no information has been captured yet.
When I start the capture and in the display filter I am using "pop or smtp" as the expression which should tell me when there is that type of traffic. Is this the correct way of doing this or is there a better way.
thanks for the help.
Mike
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Regards,
Giles Coochey, CCNA, CCNAS
NetSecSpec Ltd
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