Bloack the usb from network and add the particular device for the access, what is the method for access?

Check the article

How to Block or Allow Devices in Symantec Endpoint Protection

Hello,

How to Block or Allow Devices in Symantec Endpoint Protection

http://www.symantec.com/docs/TECH175220

http://www.symantec.com/business/support/index?page=content&id=TECH106304

How to Block or Allow Devices in Symantec Endpoint Protection

Article:TECH175220 | Created: 2011-11-23 | Updated: 2012-05-31 | Article URLhttp://www.symantec.com/docs/TECH175220

Few Articles for your Quick Accessability:

How to block USB Thumb Drives and USB Hard Drives, but allow specific USB Drives in the Application and Device Control Policy in Symantec Endpoint Protection.

http://www.symantec.com/docs/TECH106304

How to block USB flash drives while allowing other USB devices.

http://www.symantec.com/docs/TECH104299

How to block or allow device's in Symantec Endpoint Protection
https://www-secure.symantec.com/connect/articles/h...

How to block USB devices while excluding mouse and keyboard?
http://www.symantec.com/docs/TECH161779

How to block USB hard drives, but allow reading specific USB drives in the Application and Device Control Policy?
http://www.symantec.com/docs/TECH173724

Being new to the forum, here's the SEP knowledgebase location:

http://www.symantec.com/business/support/index?page=productlanding&key=54619

It should contain all the answers you need for your query.