we are having the planet perform os hardening on one of our servers and in doing so they setup iptables on our system. i had done a little research prior to them being added, but wasn't prepared for what happened next... we had over 100 clients easily that were unable to pull their email down using ms outlook / outlook express, but upon investigating a little bit further, they were able to go in and use horde webmail just fine...

another odd occurance was that a few of our clients who use ie7 and windows explorer to store and retrieve files from their web folders were able to login and move files just fine until the iptables were turned on and then they were all booted out of the system and unable to log back in using any browser, (mozilla, ie, etc.)... once the iptables were turned off everything went back to functioning normally again.

our tech from the planet says that no ports were closed and that the issues w/ ie7 were probably related to standard / passive mode. I can see his theory just fine, but my question is, how do we get past this and move forward w/ hardening our OS? we certainly don't have the manpower to follow up w/ 100 clients unable to access their email using OUtlook or Express...

just wondering if anyone out here had ever encountered this before and had any advice they could throw our way.

Also, I noticed that PLESK has a firewall built into it as well, it looks pretty straightforward from a management perspective, are there any drawbacks to using it as opposed to iptables?

Thanks for your help in advance,


Cotton Rohrscheib, Partner
Pleth Networks, LLC
http://www.pleth.com