Wireshark-users: Re: [Wireshark-users] need to find what blocks icmp
From: Marc Luethi <netztier@xxxxxxxxxx>
Date: Thu, 20 Aug 2009 19:48:20 +0200
On Thu, 2009-08-20 at 00:49 -0400, Kok-Yong Tan wrote:
> Make sure there isn't a third party firewall installed on the  
> machines that nobody thought to tell you about.  

We get that at work once a year when McAffee Antivirus gets some update
and before anyone knows, it's blocking outgoing tcp/25 again (SMTP); it
seems to be some default setting (along with some other ports).

The the server guys are calling the firewallers again because "we're
being blocked when sending mail from our servers" - yeah right. I never
could understand why they were letting an antivirus program interfere
with their network stack...

I wonder however - didn't come across in this thread;

Anyone ever cared to check for successful mutual ARP resolution before
looking after lost ICMPs?