Branch Offices

Can Cisco ASA firewalls restrict Internet access to branch offices?

I have a PPP network between our three office locations. In the master location I have a DSL line connected to my Layer 2 (L2) switch via a Cisco ASA 5505 Firewall. My server (ADC/DHCP/Proxy) is connected to the L2 switch. My branch office locations obtain IP through this server. I am using a Squid...