Blocked Outbound Ports Kills Inbound Mail

Blocked Outbound Ports Kills Inbound Mail

Post by Jeff Pryo » Mon, 30 Jul 2001 06:35:02



For security reasons I would like to shut down traffic on all high numbered
outbound TCP ports.  When I do this however I am no longer able to receive
inbound SMTP mail
I am using Exchange 5.5 SP4
Watchguard SOHO Firewall

I can watch the log on the firewall and as soon as I get  inbound SMTP
packets from an IP address my Exchange server (I assume) responds with
outbound packets on randomly numbered ports ranging from 3500 to 60000.  The
mail is never queued and seems to get lost in space.
Has anyone made this configuration work or does anyone know what is going
on?  I am have searched Technet and can't find any related articles.  I even
asked a Microsoft Tech Rep if he knew what was going on while I was trying
to resolve another issue and he said he had no idea what was happening.

 
 
 

Blocked Outbound Ports Kills Inbound Mail

Post by Ray » Mon, 30 Jul 2001 10:39:52


Are you running Windows 2000 internal DNS? Seems to me it differs from
NT 4 DNS in that it accepts queries on 53 but responds on random high
ports. If this is the case, I think there is a registry mod to make it
use port 53 exclusively. I know you did mention TCP, but did you mean
UDP also?

Ray


Quote:> For security reasons I would like to shut down traffic on all high
numbered
> outbound TCP ports.  When I do this however I am no longer able to
receive
> inbound SMTP mail
> I am using Exchange 5.5 SP4
> Watchguard SOHO Firewall

> I can watch the log on the firewall and as soon as I get  inbound SMTP
> packets from an IP address my Exchange server (I assume) responds with
> outbound packets on randomly numbered ports ranging from 3500 to
60000.  The
> mail is never queued and seems to get lost in space.
> Has anyone made this configuration work or does anyone know what is
going
> on?  I am have searched Technet and can't find any related articles.
I even
> asked a Microsoft Tech Rep if he knew what was going on while I was
trying
> to resolve another issue and he said he had no idea what was
happening.


 
 
 

1. Blocked Outbound Ports Stops Inbound Mail

For security reasons I would like to shut down traffic on all high numbered
outbound TCP ports.  When I do this however I am no longer able to receive
inbound SMTP mail
I am using Exchange 5.5 SP4
Watchguard SOHO Firewall

I can watch the log on the firewall and as soon as I get  inbound SMTP
packets from an IP address my Exchange server (I assume) responds with
outbound packets on randomly numbered ports ranging from 3500 to 60000.  The
mail is never queued and seems to get lost in space.
Has anyone made this configuration work or does anyone know what is going
on?  I am have searched Technet and can't find any related articles.  I even
asked a Microsoft Tech Rep if he knew what was going on while I was trying
to resolve another issue and he said he had no idea what was happening.

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