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tmckinney01Flag for United States of America

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Block Port 25

We have a SonicWall TZ170 with the enhanced OS as our network firewall.  We have had issues with PC's on the network sending spam so I would like to block all traffic on port 25 unless it comes from the Exchange server.  Can anyone help me with this, my SonicWall OS skills are pretty good, if you can get me pointed in the right direction that would be great.

Thanks.
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Paul Solovyovsky
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You'll have to have a rule that says the following
source:  ip address of mail server
dest:  all
protocol 25 (smtp)
set rule to allow

RIght now you probably have source set to all for smtp

What firmware are you running?
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Actually, wouldn't i need to first add a rule blocking all SMTP traffic, and then add a rule allowing it from the mail server IP?
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moorhouselondon
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It depends, if you have egress filtering meaning that you only allow know ports out than you only need to add the rule.  If you have allow all out by default you will either need to exclude the other ip addresses or setup egress filtering with a impicit deny all rule (if anything doesn't match any of the allowed then drop)

Most firewall will allow you to create a rule stating allow single ip address out on a certain port than right under that you should have deny all on that port. Most firewalls will do the checking in order the rules were setup.
Thank you for you answer.  It provided a complete solution that could be implemented without further explanation.