antivirus software for DMS computers???

[Pierre Dufresne <pierre.dufresne () messf gouv qc ca>]

Hi,

We currently have a typical DMZ made up with some web servers between an external firewall and an internal firewall. 
Because of "historical reasons", none of these machines are equipped with antivirus software.

For the sake of defense in depth, I would like to install antivirus sorftware on each of these machines.  

Someone in my company argues that we shouldn't do it because it could have a negative impact on performance.  He also 
mentions that since firewalls act as some sort of routers between networks, they are not "directly" vulnerable to virus 
attacks.  As for the web servers, they also should be less prone to viruses since they are hardened servers which get 
patched more rapidly than others.
What do you think of this?  

I just would like to know if everyone on this list protect their DMZ machine with antivirus software? It seems to me 
like standard good practice.

Thank you!

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