SBS 2003 not allowing incoming traffic

Anteksxm used Ask the Experts™
Hello Experts,

We're having some network issues with a Windows 2003 Small Business Server. As of this morning it is blocking all incoming network traffic. Services like DHCP, DNS, shares, etc are not working. From the server we can ping workstations/network devices on the network but we can not ping the server from any network device. The server has a working internet connection. Internet browsing works fine and we can even establish a remote connection to the server using LogMeIn Rescue, since it's initiated by the server. As far as we can tell there is no firewall of any kind installed on the server and the ICS service is not running. So we're stuck with what looks like a firewall problem without a firewall.

Here's what we've tried so far:
-Applied all available Windows Updates.
-Ran the SBS  Internet Connection Wizard allowing all web services.
-Used NETSH to reset TCP stack
-Plugged the server and a laptop directly into a separate switch to eliminate any possibility of environmental problems.
-Tried a new NIC.

I'm hoping one of you can offer another suggestion on what else we can try. If you require more information please let me know and I'll try to post it. Thanks!
Watch Question

Do more with

Expert Office
EXPERT OFFICE® is a registered trademark of EXPERTS EXCHANGE®
Top Expert 2011
Please set the IPSec services service to disabled and then reboot the server.  All will hopefully be well after the reboot.



It worked! Thanks!

I had the exact same issue as the original poster. I found that NAT and ICS had gotten turned on. Not sure how, but once stopped the machine behaved normally again.

Do more with

Expert Office
Submit tech questions to Ask the Experts™ at any time to receive solutions, advice, and new ideas from leading industry professionals.

Start 7-Day Free Trial