We are trying to install a DMZ Server for Symantec and was wondering what ports do we need to use in order for the DMZ Server to work so that pc's that are not on the network can still communicate with the symantec server.

This KB article will tell you

Best Practices: Configuring a Symantec Endpoint Protection environment in a DMZ

You can also check this one for clients and better securing them

Security recommendations regarding SEP client installed on server located in DMZ

Firewall Configuration (bi-directional):

Mandatory Firewall Ports:

TCP 1433: Default SQL Port

Optional Firewall Ports:

TCP 334: RDP

TCP 9090: SEPM Remote Management Console

Best Practices: Configuring a Symantec Endpoint Protection environment in a DMZ

http://www.symantec.com/business/support/index?page=content&id=TECH178325

Hi,

Few more helpful links:

How to allow Symantec Endpoint Protection clients in a remote location to be managed by a Symantec Endpoint Protection Manager that's behind a NAT device

http://www.symantec.com/docs/TECH93033

Ports and Protocols to be allowed when using a proxy in a SEP environment.

 http://www.symantec.com/docs/TECH131843 

Which Communications Ports does Symantec Endpoint Protection use?

http://www.symantec.com/docs/TECH163787

Hello,

Please check this Thread: https://www-secure.symantec.com/connect/forums/server-dmz

and check these Articles:

Best Practices: Configuring a Symantec Endpoint Protection environment in a DMZ

http://www.symantec.com/business/support/index?page=content&id=TECH178325

SEP Configuration for DMZ Servers

https://www-secure.symantec.com/connect/articles/sep-configuration-dmz-servers

Security recommendations regarding SEP client installed on server located in DMZ

http://www.symantec.com/docs/TECH122858

Communication issues with SEP client installed in DMZ while the SEP Manager is outside DMZ

http://www.symantec.com/docs/TECH146736

Updating downloads in an internal LiveUpdate Administrator 2.x Server using the downloads from an external LiveUpdate Server

http://www.symantec.com/docs/TECH106254

NOTE: The above Articles applies to both SEP 11.x and SEP 12.1

Hope that helps!!